beaumont site visit: mexican rice borer and sugarcane ...€¦ · beaumont site visit: mexican rice...

Beaumont Site Visit: Mexican Rice Borer and Sugarcane Borer

Sugarcane and Rice Research

Project Investigators:

Post-Doctoral Researcher: Research Associate: Graduate Assistant:

Gene Reagan, LSU AgCenter M.O. Way, Texas A&M AgriLife Research Julien Beuzelin Blake Wilson Matt VanWeelden

Cooperators: Texas A&M AgriLife Research & Extension Ctr., Beaumont

Ted Wilson, Professor and Center Director Lee Tarpley, Associate Professor

Yubin Yang, Senior Systems Analyst Fugen Dou, Assistant Professor

Mark Nunez and Rebecca Pearson, Research Associates USDA ARS

Bill White, Research Scientist (Sugarcane Research Station at Houma, LA) Allan Showler, Research Scientist (Kika de la Garza Research Station at Weslaco, TX)

LSU AgCenter Natalie Hummel, Associate Professor, Extension Entomology

Louisiana Dept. of Agriculture and Forestry Tad Hardy, State Entomologist

American Sugarcane League Rio Grande Valley Sugar Growers, Inc.

28 September, 2011

This work has been supported by grants from the USDA NIFA, Southern Region IPM, Crops at Risk IPM, NRI AFRI Sustainable Bioenergy, and US EPA Strategic Agricultural Initiative programs. We also thank the Texas Rice Research Foundation, the American Sugar Cane League and Rio Grande

Valley Sugar Growers Inc, participating Agricultural Chemical Companies, the Texas Department of Agriculture and the Louisiana Department of Agriculture and Forestry for their support.

Comparison of Stem Borers Attacking Sugarcane and Rice

Photos: (a) B. Castro; (b) J. Saichuk; (c) F. Reay-Jones; (d)(e)(f) A. Mészáros

(a) Adult female sugarcane borer (b) Sugarcane borer larva

(c) Adult female Mexican rice borer (d) Mexican rice borer larva

(e) Adult female rice stalk borer (f) Rice stalk borer larva

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TABLE OF CONTENTS

Comparison of Stem Borers Attacking Sugarcane and Rice ............................................................ 2

Table of Contents .............................................................................................................................. 3

Field Research Site Visit Announcement ......................................................................................... 4

Ten Years of Stem Borer Research Collaboration on Sugarcane and Rice ...................................... 5

Monitoring Mexican Rice Borer Movement: Range Expansion into Louisiana .............................. 7

Evaluation of Commercial and Experimental Sugarcane Cultivars for Resistance to the Mexican Rice Borer, Beaumont, TX, 2010 and 2011 .................................................................. 9

Feeding Behavior and Duration of Exposure of Mexican Rice Borer Larvae on Sugarcane ......... 12

Red Imported Fire Ant Predation on Mexican Rice Borer in Sugarcane at Beaumont, TX in 2011 ............................................................................................................................................ 13

Pheromone Trap Assisted Scouting and Aerial Insecticidal Control of the Mexican Rice Borer, 2009 and 2010 ................................................................................................................. 14

Comparison of Mexican Rice Borer Pest Pressure in Bioenergy and Conventional Sugarcane ................................................................................................................................... 16

Small Plot Assessment of Insecticides Against the Sugarcane Borer, 2011 ................................... 18

Field Assessment of Novaluron for Sugarcane Borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), Management in Louisiana Sugarcane ............................................. 19

Seasonal Infestations of Two Stem Borers (Lepidoptera: Crambidae) in Non-Crop Grasses of Gulf Coast Rice Agroecosystems .......................................................................................... 28

Harvest Cutting Height and Ratoon Crop Effects on Stem Borer Infestations in Rice .................. 43

Trapping for Mexican Rice Borer in the Texas Rice Belt, 2010 .................................................... 45

Rice Insecticide Evaluation Studies ................................................................................................ 46

Beaumont Sugarcane and Energycane Variety Test, 2010 ............................................................. 50

Beaumont Sugarcane and Energycane Variety Test, 2011 ............................................................. 51

Example Data Sheet ........................................................................................................................ 52

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2011 Field Research Site Visit Announcement To: Louisiana and Texas Sugarcane and Rice Consultants, Agricultural Extension Agents, and Industry

Cooperators From: Gene Reagan and Mo Way LSU AgCenter and Texas A&M Entomologists Re: Texas AgriLife Research and Extension Center at Beaumont Mexican Rice Borer and Sugarcane Borer Field Research Observations

ITINERARY Tuesday, 27 September – 6:15 pm Meet in lobby of Holiday Inn and Suites to go to dinner

probably at Papadeaux’s (optional) Wednesday, 28 September – 8:00 am Meet in front of Texas AgriLife Research and Extension Center: - Dr. Ted Wilson (Center Director): Welcome and introduction

- Dr. Gene Reagan: Overview of planned activities, handouts, and instructions to go to the field

ACTIVITIES

1. Tad Hardy (LA State Entomologist): Review of LA Dept. Ag & Forestry MRB pheromone trap monitoring 2. Dr. Bill White: Variety diversity in the test 3. Dr. Gene Reagan, Dr. Julien Beuzelin, and Mr. Blake Wilson: Hands-on sampling for Mexican rice borer

( MRB) and sugarcane borer (SCB) injury in sugarcane varieties 4. Observe MRB and SCB larvae in replicated test of LA sugarcane varieties (HoCP 08-726, Ho 08-711, L

08-092, HoCP 91-552, L 07-57,Ho 08-706, Ho 08-717, L 79-1002, Ho 02-113, HoCP 04-838, L 08-090, HoL 08-723, Ho 08-709, HoCP 00-950, Ho 07-613, L 08-088, L08-075, HoCP 85-845, Ho 05-961)

5. Mr. Blake Wilson: Use of MRB pheromone traps to help with scouting. 6. Dr. Julien Beuzelin and Mr. Matt VanWeelden: Multi-crop bioenergy research. 7. Dr. Mo Way: Observe MRB and SCB damage and discuss insecticides and cultural practices in rice

or visit demonstration of sugarcane stalk splitter machine (Gene Reagan). Wednesday, 28 September – 11:00 am Sun grant/Chevron/Beaumont energy cane and high biomass

sorghum research near main building, Texas AgriLife Research and Center at Beaumont, 1509 Aggie Dr., approx. 9 miles west of Beaumont on Hwy 90.

Wednesday, 28 September – Noon Adjourn and return home

RESERVATION AND HOTEL INFORMATION For hotel reservations call 409-842-5995 Any time prior to Tuesday, 20 September Reservation Code: LSU Entomology

You may reserve rooms with Samantha by email at: [email protected]

$79.00 + tax reduced rate, Breakfast buffet (6:00 AM) included

LOCATION Please do not take any live insects from this location!

Texas AgriLife Research and Extension Center at Beaumont 1509 Aggie Drive, Beaumont, TX 77713

DIRECTIONS TO RESEARCH SITE: 9.5 miles west of Beaumont on Hwy 90, ~ 1 mile north on Aggie Drive

HOTEL ADDRESS: Holiday Inn and Suites 3950 I-10 South Beaumont, TX 77705 409-842-7822 (hotel) 409-842-7810 (fax)

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TEN YEARS OF STEM BORER RESEARCH COLLABORATION ON SUGARCANE AND RICE

Gene Reagan and M.O. Way*

LSU AgCenter and Texas A&M AgriLife Research

The Mexican rice borer (MRB), Eoreuma loftini (Dyar), is the most destructive insect pest of sugarcane in North America. This invasive alien species entered the Lower Rio Grande Valley (LRGV) of Texas in 1980, and quickly caused such severe losses that sugarcane farmers were unable to harvest some of their fields. MRB continued to expand its geographical range throughout the Texas Gulf Coast rice producing area and into western Louisiana, now infesting rice in all of Calcasieu Parish (Lake Charles area). Causing as much as 50% yield loss in commercial Texas rice fields, projected economic loss to the Louisiana sugarcane and rice industries may be expected to reach as much as $220 million (sugarcane) and $45 million (rice) annually when MRB becomes fully established. The MRB is also a serious pest of sorghum and corn in Texas. The sugarcane borer (SCB), Diatraea saccharalis (F.), continues to be a serious pest of sugarcane in Louisiana and is also a key pest of rice and non-transgenic corn.

MRB was first discovered in the Texas rice belt in 1988 and soon received attention from producer organizations and support industries. At this time, little was known about the biology and ecology of the pest, and even less was known about possible management techniques. After a several million dollar biological control program proved unsuccessful with LRGV sugarcane growers, we knew that control efforts would have to be much more comprehensive. This would require a far greater knowledge of MRB biology and how its life history relates to different host plants.

On behalf of the LSU AgCenter and Texas A&M University, we initiated a national competitive grant effort in 2001 starting with $40,000 seed money from the USDA (CSREES) Critical Issues program and a project titled “MRB identification of range and variety resistance assessment.” In addition to three multi-year Strategic Agricultural Initiative grants from the US Environmental Protection Agency, we were successful in obtaining five years of support from two USDA Crops-at-Risk grants. All of these grants have been oriented toward building a system for sugarcane and rice that would not only help to manage stem borer problems, but also reduce area-wide pest populations. This year, our team was expanded to include L.T. Wilson and Yubin Yang (Texas A&M AgriLife), Allan Showler (USDA-ARS), and Jeff Hoy (LSU AgCenter Plant Pathology) for a sustainable biomass energy grant to further mitigate insect and disease pressures on conventional crops in interaction with potentially emerging bioenergy cropping systems.

* Thomas E. (Gene) Reagan, Austin C. Thompson Endowed Professor of Entomology, Louisiana State University Agricultural Center; and M.O. Way, Professor of Entomology, Texas A&M AgriLife Research and Extension Center at Beaumont

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During the ten years of our collaborative work, we have developed sampling approaches to monitor infestations and quantify pest populations, identified resistant varieties, and evaluated and helped label environmentally friendly insecticides. With colleagues, we have studied numerous plant-insect interactions involving crop and non-crop host preferences, and better defined the role of plant stress impacted by cultural practices, salt, water and nutrients. Techniques reducing scouting efforts and achieving better insecticide application timing were also developed to assist sugarcane consultants. With recently labeled insecticides having four different modes of action (Confirm®, Diamond®, Coragen® / Belt®, Besiege®), the potential for insecticide resistance is also reduced. In rice, a newly developed seed treatment, Dermacor X-100®, impacts stem borer management in addition to pyrethroid foliar applications.

Thank you for participating in the 10th stem borer research site visit training. We welcome you to the 2011 Beaumont Site Visit and hope you depart with good information to help you grow a more profitable crop.

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MONITORING MEXICAN RICE BORER MOVEMENT: RANGE EXPANSION INTO LOUISIANA

T. Hardy1, T.E. Reagan2, M.O. Way3, R.A. Pearson3, B.E. Wilson2, and J.M. Beuzelin2

1Louisiana Department of Agriculture and Forestry; 2Department of Entomology, LSU AgCenter 3Texas A&M AgriLife Research and Extension Center at Beaumont

Cooperative studies on the Mexican rice borer (MRB), Eoreuma loftini, between the LSU

AgCenter, Texas A&M University AgriLife Research Center at Beaumont, the Texas Department of Agriculture, and the Louisiana Department of Agriculture and Forestry have been on-going since 1999 to monitor the movement of this devastating pest of sugarcane towards Louisiana. As previously anticipated, MRB spread into Louisiana by the end of 2008, and was collected in two traps near rice fields northwest of Vinton, LA on December 12. While no MRB specimens were detected in Louisiana in 2009, data from 2010 showed that this invasive pest had expanded its range into Cameron and Calcasieu parishes. Additional MRB moths captured in 2011 indicate the species has expanded its range farther north into southeastern Beauregard Parish.

The first specimens trapped since 2008 were collected in non-crop habitat with wild grass hosts 6.8 miles southeast of Vinton, Calcasieu parish, LA, on 22 November 2010. Since that date, numerous specimens have been collected in traps from 36 different locations in Louisiana (Table 1, Fig. 1). Currently, the locations of positive traps have been in rice or wild-host areas; however, the eastern-most location is directly south of Lacassine, and it is anticipated the MRB will soon infest producing sugarcane in that region. More than 200 MRB have been trapped in Calcasieu parish so far in 2011 (Table 1), indicating the species has established a clear presence. Additionally, rice growers in this parish have begun to report MRB larval infestations in their fields. In August, traps were retrieved and/or re-deployed east of their previous locations in an attempt to stay ahead of the eastern MRB movement (Table 2). Continued monitoring of MRB populations will be conducted with additional traps at locations further east and north. Currently, LDAF has a total of 25 MRB pheromone traps in Calcasieu, Cameron and Jefferson Davis parishes, with 3 additional traps in Beauregard and Vermilion parishes. In late September, 12 traps will be added in St. Mary and Iberia parishes near sugarcane processing and off-loading facilities. As the pest’s eastward expansion continues, effective management strategies such as the use of varietal resistance, improved chemical control tactics, and management of non-crop hosts are becoming critical to slow the spread of this devastating insect. Table 1. 2011 Louisiana MRB Trap Captures Table 2. Monthly Total MRB Captures in LA

Month # MRB March 36 April 59 May 36 June 57 July 19

August 32

Parish # Sites # + Sites # MRB Calcasieu 34 24 209 Cameron 14 11 27

Beauregard 2 1 3 Jefferson Davis 12 0 0

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References: Hummel, N.A., T. Hardy, T.E. Reagan, D.K. Pollet, C.E. Carlton, M.J. Stout, J.M. Beuzelin, W. Akbar, W.H. White. 2010. Monitoring and first discovery of the Mexican rice borer Eoreuma loftini (Lepidoptera: Crambidae) in Louisiana. Fla. Entomol. 93: 123-124. Hummel, N., G. Reagan, D. Pollet, W. Akbar, J. Beuzelin, C. Carlton, J. Saichuk, T. Hardy, M. Way. 2008. Mexican Rice Borer, Eoreuma loftini (Dyar). LSU AgCenter Pub. 3098. Reay-Jones, F.P.F., L.T. Wilson, M.O. Way, T.E. Reagan, C.E. Carlton. 2007. Movement of the Mexican rice borer (Lepidoptera: Crambidae) through the Texas rice belt. J. Econ. Entomol. 100: 54-60. Reay-Jones, F.P.F., L.T. Wilson, T.E. Reagan, B.L. Legendre, and M.O. Way. 2008. Predicting economic losses from the continued spread of the Mexican rice borer (Lepidoptera: Crambidae). J. Econ. Entomol. 101: 237-250.

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EVALUATION OF COMMERCIAL AND EXPERIMENTAL SUGARCANE CULTIVARS FOR RESISTANCE TO THE MEXICAN RICE BORER, BEAUMONT,

TX, 2010 AND 2011

T.E. Reagan1, B.E. Wilson1, J.M. Beuzelin1, W.H. White2, M.O. Way3, M. VanWeelden1, and A.T. Showler4

1Department of Entomology, LSU AgCenter 2USDA Sugarcane Research Unit at Houma, Louisiana

3Texas A&M AgriLife Research and Extension Center at Beaumont, Texas 4USDA-ARS, Kika de la Garza Agricultural Research Center at Weslaco, Texas

Because of the limitations of chemical and biological control against the Mexican rice

borer (MRB), Eoreuma loftini, host plant resistance is an important part of management. As a control tactic, host plant resistance can not only aid in reducing stalk borer injury, but can also reduce area-wide populations and potentially slow the spread of the MRB. The effect of cultivars on reducing area-wide populations is examined by comparing the number of adult emergence holes. In addition, recent research suggests resistant cultivars which impede stalk entry and prolong larval exposure on plant surfaces may enhance the efficacy of insecticide applications. Continued evaluation of stalk borer resistance is necessary as host plant resistance remains a valuable integrated pest management (IPM) tool.

A 2-year field study was conducted at the Texas A&M AgriLife Research and Extension Center at Beaumont, TX, to assess resistance to MRB among commercial and experimental sugarcane cultivars. Thirty-eight cultivars were evaluated over both years. The tests included a wide variety of cultivars developed from breeding programs in St. Gabriel, LA; Houma, LA; Canal Point, FL; and Natal, South Africa. In addition, the tests examined resistance in 4 biomass energy cultivars. In both years, the tests had 1-row, 12-foot plots arranged in a randomized block design with 5 replications (See field maps pp. 50-51).

2010 evaluation

The 25 varieties evaluated in 2010 include: 5 in commercial use (HoCP 85-845, HoCP 96-540, HoCP 00-950, L 01-299, and L 03-371), 11 experimental clones (HoCP 05-902, HoCP 05-961, HoCP 04-838, Ho 06-563, Ho 07-613, Ho 07-604, Ho 07-617, Ho 07-612, Ho 06-537, L 07-68, and L 07-57), 3 clones bred for high fiber content (Ho 06-9610, US 93-15, and US 01-40), 2 energy canes (US 08-9001 and US 08-9003), and 4 South African cultivars (N-17, N-21, N-24, N-27). The cultivars from the South African Sugar Research Institute in KwaZulu-Natal (N-cultivars) have potential resistance to MRB because they have demonstrated varying levels of resistance to African stalkborers, especially Eldana spp., which shares many characteristics with MRB.

Differences were detected in percentages of bored internodes among cultivars (F=3.56, P<0.001). Results (Table 1) showed infestations ranging from 1.0% bored internodes (N-21 and HoCP 85-845) to 20.4% (Ho 06-563). Of the commercial cultivars, HoCP 85-845 and L 01-299 were the most resistant, while L 03-371 and HoCP 96-540 were the most susceptible. HoCP 96-540, currently the most widely planted cultivar in Louisiana, experienced nearly 8-fold more injury than the most resistant varieties. All of the South African cultivars showed some level of resistance with N-21 being the most resistant. Adult emergence data followed the same trend as percent bored internodes with moth production ranging from < 0.01 to 0.38 emergence holes/stalk (Table 1); however, differences in emergence among cultivars were not detected (F=1.57, P=0.065).

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Table 1. MRB injury and moth production in the 2010 Beaumont sugarcane variety test

Variety % Bored Internodes Emergence per

Stalk Ho 06-563 20.4 0.38

HoCP 05-902 14.5 0.32 HoCP 04-838 11.0 2.0

Ho 07-612 10.1 0.18 L 03-371 9.6 0.14

HoCP 96-540 7.9 0.08 L 07-57 7.2 0.31

Ho 07-604 6.4 0.04 US 01-40 5.9 0.06

N-27 5.8 0.12 Ho 06-537 5.8 0.18 Ho 07-613 5.5 0.02

N-17 5.4 0.08 HoCP 05-961 5.3 0.12 US 08-9001 5.3 0.04 Ho 06-9610 5.0 0.04

HoCP 00-950 4.6 0.04 L 07-68 4.1 0.12

Ho 07-617 3.9 0.06 US 08-9003 2.7 0.06

N-24 2.4 <0.01 L 01-299 2.3 0.04 US 93-15 1.2 0.011

HoCP 85-845 1.0 <0.01 N-21 1.0 <0.01

*Means which share a line are not significantly different (LSD, α=0.05)

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2011 evaluation The 2011 test evaluated resistance in 19 cultivars. Cultivars from the 2010 test which

were reevaluated include: HoCP 85-845, HoCP 00-950, Ho 07-613, L 07-57, HoCP 05-961, and HoCP 04-838. HoCP 85-845 has been our resistant standard for several years. HoCP 04-838, which appears to have little resistance to the MRB, has recently been released to commercial growers. Experimental cultivars in the early stages of varietal development include: HoCP 08-726, Ho 08-706, L 08-090, L 08-088, Ho 08-711, Ho 08-717, HoL 08-723, L 08-075, L 08-092, Ho 08-709. Two energy cane varieties, L 79-1002 and Ho 02-113, were also evaluated. Results showed significant differences (F=2.71, P= 0.002) in injury, ranging from 1.9 to 17.2% bored internodes (Table 2). The most resistant cultivars examined were HoCP 85-845 and L 08-075. Experimental cultivar L 08-075 is potentially highly resistant as it demonstrated >8-fold reductions in MRB injury compared to susceptible cultivars. The most susceptible cultivars were HoCP 08-726, L 08-090, and HoCP 04-838. Differences in adult emergence (F= 1.99, P =0.019) followed the same trend as injury data ranging from 0.02 to 0.45 emergence hole per stalk (Table 2). Results from the cultivars which were reevaluated were consistent with findings from 2010. Energy cane varieties showed intermediate levels of resistance. Table 2. MRB injury and moth production in the 2011 Beaumont sugarcane variety test

Variety % Bored Internodes Emergence/stalk HoCP 08-726 17.2 0.45

L 08-090 13.7 0.35 HoCP 04-838 13.4 0.28 HoL 08-723 13.1 0.10 Ho 08-711 13.1 0.46 Ho 08-717 12.4 0.20 Ho 08-706 9.5 0.18 Ho 07-613 9.0 0.27 L 79-1002 8.5 0.21

L 07-57 8.5 0.21 Ho 08-709 8.0 0.07 L 08-088 8.0 0.23

HoCP 00-950 7.9 0.08 Ho 02-113 7.7 0.08 L 08-092 7.7 0.08

Ho 05-961 7.6 0.24 HoCP 91-552 7.6 0.23 HoCP 85-845 3.9 0.10

L 08-075 1.9 0.02 *Means which share a line are not significantly different (LSD α=0.05).

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FEEDING BEHAVIOR AND DURATION OF EXPOSURE OF MEXICAN RICE BORER LARVAE ON SUGARCANE

Blake E. Wilson1, T.E. Reagan1, J.M. Beuzelin1, and A.T. Showler2

1Department of Entomology, LSU AgCenter 2USDA-ARS Weslaco, Texas

A greenhouse study was conducted at the USDA ARS Kika de La Garza Subtropical

Agricultural Research Center (Weslaco, Hidalgo County, TX) to investigate Mexican rice borer (MRB), Eoreuma loftini, larval feeding behavior on immature (6 nodes) and mature (12 nodes) sugarcane stalks of a resistant (HoCP 85-845) and susceptible (HoCP 00-950) cultivar. Plants were arranged in a completely randomized design with each of the four treatments (cultivar by phenological stage) applied to 12 stalks. Strips of freshly laid MRB eggs were attached to the leaves at locations consistent with normal oviposition activity. Egg strips were removed after hatching, and position and feeding behavior of newly emerged larvae were recorded daily. Numerous entry holes into leaf midribs within one day of hatching indicated that many larvae were only briefly exposed on plant surfaces. The number of larvae to enter the midribs, duration of exposure, and larval survival were recorded.

Over all treatments ,feeding behavior and establishment of a total of 277 larvae was monitored (Table 1). More than half of newly hatched larvae on immature stalks of HoCP 00-950 bored into the plant (midrib), where they would be protected from contact insecticides within one day. A greater percentage of larvae became established feeding on the susceptible HoCP 00-950 than on HoCP 85-845. Larval establishment was greater on mature than on immature sugarcane. However, larval survival to stalk entry was greater on immature than mature sugarcane, which may be related to increasing rind hardness as stalks mature. Duration of exposure was shortest on immature HoCP 00-950 (3.4 d) and greatest on mature stalks of HoCP 85-845 (6.4 d). This research demonstrates the short window of exposure of MRB larvae to control tactics. Because of the limited vulnerability of MRB larvae, improved application timing and residual activity of insecticides have potential to enhance efficacy of MRB chemical control. Additionally, resistant cultivars which impede larval establishment and prolong exposure would likely allow increased larval vulnerability to chemical or biological control tactics. Table 1. MRB larval behavior and exposure on sugarcane, Weslaco, TX, 2010

% of larvae to establish feeding

% of larvae to enter midrib in

1 day

Duration of exposure (day)

% of established larvae surviving

to stalk entry HoCP 00-950

6 Nodes 18.2 67.5 3.40 55.0 12 Nodes 31.0 42.5 5.38 41.0

HoCP 85-845 6 Nodes 14.1 24.1 5.95 72.4

12 Nodes 21.9 32.9 6.41 27.4

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RED IMPORTED FIRE ANT PREDATION ON MEXICAN RICE BORER IN SUGARCANE AT BEAUMONT, TX IN 20111

M.T. VanWeelden1, J.M. Beuzelin1, B.E. Wilson1, T.E. Reagan1, and M. O. Way2

1Department of Entomology, LSU AgCenter 2Texas A&M AgriLife Research and Extension Center at Beaumont, Texas

A study was initiated in the summer of 2011 at the Texas A&M AgriLife Center at

Beaumont, TX to assess the effect of predation by the red imported fire ant (Solenopsis invicta) on Mexican rice borer (MRB) injury to sugarcane. The experiment was conducted in plots of the 2010 and 2011 sugarcane variety tests by establishing ant-suppressed and unsuppressed areas. Ant populations were suppressed using a granule bait formulation of hydramethylnon and S-methoprene applied to the rows and bases of plants.

In each area of the variety tests, MRB injury was assessed in four sugarcane cultivars of interest; two conventional cultivars and two energy cultivars (Table 1). Bored internodes and emergence holes from MRB were counted on 10 randomly selected stalks from each plot using destructive sampling and a stalk-splitter machine borrowed from the Texas A&M Center at Weslaco. The percentage of bored internodes and number of emergence holes were analyzed using generalized linear models (Proc Glimmix, SAS Institute) with binomial and Poisson distributions, respectively.

A 50% increase in the percentage of bored internodes was observed across all ant-suppressed areas. However, statistical analysis did not detect differences (F=1.48, P=0.284) supporting the numerical trend (Table 1). A difference in emergence holes per stalk was associated with ant suppression (F=2.43, P=0.023). The mean number of emergence holes per stalk across all unsuppressed areas was 0.16, and increased to 0.36 in areas where ants were suppressed. This data suggests that predation of the MRB by the red imported fire ant decreases both injury and build-ups of pest populations in sugarcane. Additional data collected from pitfall traps implemented throughout the summer to detect relative abundance of the red imported fire ant may help to better quantify the role of ant predation. MRB infestations in leaf sheaths recorded bi-weekly still need to be analyzed.

Table 1. Mean percentage of bored internodes and emergence per stalk by sugarcane cultivar with ants suppressed and unsuppressed in Beaumont, TX, 2011

Variety Ants Suppressed Ants Not Suppressed

% Bored internodes Emergence/stalk % Bored internodes Emergence/stalk HoCP 85-845

(plant and ratoon) 6.28 0.1 3.36 0.07

HoCP 04-838 (plant and ratoon) 11.67 0.4 9.61 0.15

Ho 02-113 (plant) 6.51 0.14 7.79 0.06

L 79-1002 (plant) 6.62 0.23 9.76 0.22

Ho 08-9001 (ratoon) 17.48 0.4 9.19 0.15

Ho 08-9003 (ratoon) 33.88 0.99 13.04 0.3

1 This research is part of the Ph.D. dissertation program of Matt VanWeelden

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PHEROMONE TRAP ASSISTED SCOUTING AND AERIAL INSECTICIDAL CONTROL OF THE MEXICAN RICE BORER, 2009 AND 2010

Blake E. Wilson1, T.E. Reagan1, J.M. Beuzelin1, and A.T. Showler2

1Department of Entomology and 2USDA-ARS Weslaco, Texas

A 2-year field study was conducted to evaluate the use of pheromone traps to enhance scouting and improve chemical control of the Mexican rice borer (MRB), Eoreuma loftini, in commercial sugarcane fields in the Lower Rio Grande Valley (Cameron County, Texas). Evaluation of aerial insecticide applications for control of MRB was conducted in a large area randomized block design (RBD) with 5 replications. Insecticide treatments were assigned randomly to plots (10 acres/plot) in fields ranging from 36-85 acres of variety CP 72-1210 (ratoon) in 2009 and 2010. Pheromone traps were used to help with scouting and better monitor MRB population densities to more effectively time the need for insecticide applications. Trap catches of >20 moths/trap/week were used as a scouting threshold to initiate monitoring for larval infestations in (Fig. 1A). Treatable larval infestations (on plant surfaces) were determined by examining two ten stalk samples per plot. In 2009, one incident of larval scouting was necessary to determine that infestations exceeded the threshold of 5% of stalks with larvae on plant surfaces. Weekly larval scouting was conducted in 2010 throughout the growing season, and a direct correlation was observed between pheromone trap catches and larval infestations (Fig. 1B). A single aerial application was made in both 2009 and 2010 on mornings of 21 Aug and 13 Aug, respectively, by fixed wing aircraft at 10 GPA with less than 5 mph wind. At the end of the growing season, injury data were collected from 30 stalks/plot. Yield data in 2010 were collected with the core sampling method with each 10 acre plot harvested completely.

In both 2009 and 2010, the recently labeled (Section 3 for sugarcane) environmentally friendly insecticide, novaluron (Diamond®), showed the best control with 7.6% bored internodes, which was significantly less than the untreated plots (19.1% bored) averaged over both years. β-cyfluthrin (Baythroid®) provided intermediate control (Table 1). Differences in moth emergence followed the same trend as percent bored internodes, with significant differences detected among treatments (Table 1). Yield data from 2010 indicate that the novaluron treatment led to a 14% increase in sugar production over untreated controls, while β-cyfluthrin treated plots were only significantly different from controls in terms of sugar/ton of cane (Table 1). Based on the current price of sugar (~$695.60/ton), the novaluron application reduced revenue losses by $276/acre. This study demonstrates the potential of pheromone trap-assisted-scouting to reduce scouting effort and optimally time insecticide applications. Additionally, the economics of MRB insecticidal control could be greatly improved if sugar production can be increased with a single, well-timed insecticide application.

Table 1. MRB injury and sugar yield from aerial insecticide tests, LRGV, 2009 and 2010

Treatment Rate (fl oz/acre) % Bored Emergence/Stalk Sugar(lbs)/ton

of cane Sugar

(tons)/acre Diamond® 12.0 7.6 a 0.26 a 208.2 a 3.16 a

Baythroid® 2.8 11.4 a 0.39 ab 203.0 b 2.59 b

Untreated NA 19.1 b 0.62 b 197.8 c 2.91 b

*Means which are followed by the same letter are not significantly different (P > 0.05).

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Fig. 1. Pheromone trap monitoring of MRB in Hidalgo and Cameron Counties, TX. (A) Average no. of MRB/trap/week throughout the 2009 growing season. (B) Relationship between adult population densities (no. of MRB/trap/week) and larval infestation (percent of stalks infested with treatable larvae feeding in leaf sheaths), 2010.

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COMPARISON OF MEXICAN RICE BORER PEST PRESSURE IN BIOENERGY AND CONVENTIONAL SUGARCANE1

T.E. Reagan1, B.E. Wilson1, M.T. VanWeelden1, J.M. Beuzelin1, W.H. White2, and M.O. Way3

1Department of Entomology, LSU AgCenter; 2USDA Sugarcane Research Unit at Houma 3Texas A&M AgriLife Research and Extension Center at Beaumont, Texas

A study conducted at the Texas A&M AgriLife Center at Beaumont, TX compared the

effects of Mexican rice borer (MRB), Eoreuma loftini, infestations in energycane cultivar L 79-1002 and two conventional sugarcane cultivars, HoCP 85-845 (resistant) and HoCP 04-838 (susceptible). The experiment was set up in a randomized block design arrangement with 4 replications. Each 1-row 12-ft-long plot was split into two 6-ft sub-plots. Sub-plots were either protected from MRB infestations or left unprotected. Protected sub-plots received two applications of tebufenozide (Confirm) applied at 15.0 oz/a in Jul and Aug with a back-pack sprayer containing 2 gal of water. From late Jun to late Aug, MRB larval feeding signs in leaf sheaths were monitored every other week. In early Sep, stand counts were taken from each sub-plot and10 stalk samples were collected and weighed. For each stalk, the numbers of bored internodes, total internodes, and emergence holes were recorded. Total juice volume and Brix value were recorded from 4 stalks. Juice volume/6 row-ft was calculated multiplying volume/stalk by the no. stalks/sub-plot.

Untreated MRB larval feeding injury in leaf sheaths of energycane L 79-1002 ranged between 60 and 90% of injured stalks during the initial sampling periods, and averaged 20.3 and 12.5% in HoCP 04-83 and HoCP 85-845, respectively (Table 1). Insecticide applications reduced the percentage of bored internodes (F=23.8, P<0.001) and emergence per stalk (F=5.7, P=0.024), with unprotected HoCP 04-838 and protected HoCP 85-845 sustaining the greatest and lowest levels of injury, respectively (Table 2). Energycane L 79-1002 sustained intermediate levels of injury. Differences between cultivars were detected for weight of 10 stalks (F=3.8, P= 0.0366), juice volume (F=13.1, P<0.001), and Brix (F=273.6, P<0.001). Although insecticidal protection decreased MRB injury for all cultivars, increases in yield parameters were only detected for susceptible sugarcane HoCP 04-838 (Table 3). These data suggest that HoCP 85-845 and L 79-1002 are more tolerant to MRB injury. Future quantification of the impact of MRB infestations and associated injury on yield components will be critical to determine the need for management actions in energycane. Table 1. MRB injury in leaf sheaths of sugarcane and energycane, Beaumont, TX, 2011

Cultivar Treatment* % Injured stalks

8 Jul (pre-treatment)

22 Jul 3 Aug

HoCP 85-845 (resistant)

Protected NA 0 5 Unprotected 12.5 10 15

HoCP 04-838 (susceptible)


L 79-1002 (energycane)


*Protected = Confirm® applied on July 10 and August 3

1 A portion of this study is anticipated to be part of the Ph.D. dissertation program of Matt VanWeelden

16

Table 2. MRB injury and emergence in sugarcane and energycane, Beaumont, TX, 2011

Cultivar Treatment % Bored internodes Emergence/Stalk HoCP 04-838 Unprotected 13.2 0.24 L 79-1002 Unprotected 8.1 0.19 HoCP 85-845 Unprotected 3.8 0.09 L 79-1002 Protected 2.5 0.06 HoCP 04-838 Protected 1.0 0.06 HoCP 85-845 Protected 0.5 0.02 *Means sharing a line are not significantly different (LSD, α=0.05); Protected = Confirm®

applied on July 10 and August 3 Table 3. Yield parameters as affected by cultivar and insecticide applications

Cultivar Treatment # Stalks/ 6 row ft

Weight of 10 stalks (Kg)

Juice volume (L / 6 row ft) Brix

HoCP 04-838 Protected 20.8 4.96 3.91 15.5 Unprotected 17.2 4.96 3.10 14.4

HoCP 85-845 Protected 23.4 4.46 5.05 13.3 Unprotected 20.8 4.50 4.83 13.0

L 79-1002 Protected 50.2 3.53 5.92 9.9 Unprotected 45.2 3.23 4.61 9.7

*Means sharing a line are not significantly different (LSD, α=0.05)

17

1 Border- row

SMALL PLOT ASSESSMENT OF INSECTICIDES AGAINST THE SUGARCANE BORER, 2011

B.E. Wilson1, J.M. Beuzelin1, M.T. VanWeelden1, M.O. Way2, and T.E. Reagan1

1Department of Entomology, LSU AgCenter 2Texas A&M AgriLife Research and Extension Center at Beaumont, Texas

Seven insecticide treatments (Table 1), in addition to an untreated check, are being

assessed for season-long control of the sugarcane borer (SCB), Diatraea saccharalis (F.), in a RBD with five replications in a field of variety HoCP 96-540 stubble cane at Burns Point in St. Mary Parish. Lorsban and Extinguish were applied on June 16 for suppression of red imported fire ants and other predatory arthropods. Insecticides for SCB were applied to 3-row plots (24 ft) on August 4 and 30, 2011. The treatments were mixed in water and applied with the nonionic surfactant Induce at 0.25% v/v using a Solo back pack sprayer delivering 10 gpa at 14 psi. SCB internode boring and larvae infesting leaf sheaths were observed on August 25 in selected plots. These preliminary observations helped to verify possible differences in control residual among treatments prior to the second insecticide application. SCB injury will be assessed by recording the number of bored internodes and the total number of internodes from 15 stalks per plot in early October. Table 1. Treatments applied to manage SCB in sugarcane in 2011, Burns Point, LA Treatment Trade name Common name Rate (oz/a) A Besiege Rynaxypyr + λ-

Cyhalothrin 9.0

B Belt Flubendiamide 3.0 C Control NA NA D Diamond Novaluron 12.0 E Confirm Tebufenozide 8.0 F Coragen Rynaxypyr 3.0 G Prevathon Rynaxypyr 20 H Prevathon Rynaxypyr 12 Table 2. Plot map, 2011, Burns Point, LA

Rep 5 Rep 4 Rep 3 Rep 2 Rep 1 D5 B4 A3 D2 H1 H5 C4 H3 G2 G1 E5 F4 D3 B2 F1 B5 A4 G3 E2 E1 G5 H4 B3 F2 D1 A5 D4 E3 C2 C1 F5 E4 C3 A2 B1 C5 G4 F3 H2 A1

Quarter Drain

18

Author's personal copy

Field assessment of novaluron for sugarcane borer, Diatraea saccharalis (F.)(Lepidoptera: Crambidae), management in Louisiana sugarcane

J.M. Beuzelin a,*, W. Akbar b, A. Mészáros a, F.P.F. Reay-Jones c, T.E. Reagan a

aDepartment of Entomology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, 404 Life Sciences Bldg, Baton Rouge, LA 70803, USAbMonsanto Company, 700 Chesterfield Pkwy West GG3E, Chesterfield, MO 63017, USAcDepartment of Entomology, Soils and Plant Sciences, Clemson University, Pee Dee Research and Education Center, 2200 Pocket Rd., Florence, SC 29506, USA

a r t i c l e i n f o

Article history:Received 28 January 2010Received in revised form24 May 2010Accepted 1 June 2010

Keywords:Diatraea saccharalis (F.)SugarcaneBiorational insecticideChitin synthesis inhibitorIntegrated pest management

a b s t r a c t

On-farm field experiments were conducted in 2004 and 2007 to assess the suitability of novaluron,a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisianasugarcane (Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial productionpractices were made when D. saccharalis infestation levels exceeded a recommended action threshold. Inaddition to decreased D. saccharalis infestations, 6.3 e 14.5-fold reductions in end of season injury,expressed as the percentage of bored sugarcane internodes, were observed in plots treated with nova-luron. D. saccharalis control in novaluron plots was equivalent to (P > 0.05) or better (P < 0.05) than thatachieved with tebufenozide, an ecdysone agonist that has been extensively used for over a decade onsugarcane. With a numerical trend of a 3.1-fold decrease in percent bored internodes, the pyrethroidgamma-cyhalothrin seemed less effective than the biorational insecticides in protecting sugarcaneagainst D. saccharalis. Using continuous pitfall trap sampling, no measurable (P > 0.05) decreases inpredaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides.However, numerical trends for decreases in immature crickets associated with novaluron and gamma-cyhalothrin were recorded in 2007. Our data suggest that novaluron will fit well in Louisiana sugarcaneintegrated pest management.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

The sugarcane borer, Diatraea saccharalis (F.), is a lepidopteranpest that has historically been the most damaging arthropod inLouisiana sugarcane (hybrids of Saccharum L. spp.) (Reagan et al.,1972; Reagan, 2001). Management recommendations for D. sac-charalis emphasize the importance of cultivar resistance, scouting,properly timed insecticide applications, and conservation ofbeneficial arthropods (Reagan and Posey, 2001; Posey et al., 2006).However, resistant cultivars have been underexploited for the pastdecade due to widespread use of susceptible high-yielding culti-vars, and adequate D. saccharalis control with narrow-rangeinsecticides and associated conservation of natural enemies (Reay-Jones et al., 2005).

The red importedfire ant, Solenopsis invictaBuren, is thedominantnatural enemyofD. saccharalis in Louisiana sugarcane (Reagan,1986),contributing an estimated savings of as much as two insecticideapplications per year for D. saccharalis management (Sauer et al.,

1982). Spiders (Araneae) are the primary D. saccharalis egg preda-tors and are probably second in importance in the natural enemycomplex (Negm and Hensley, 1969; Ali and Reagan, 1986). Groundbeetles (Coleoptera: Carabidae), tiger beetles (Coleoptera: Carabidae:Cicindelinae), rove beetles (Coleoptera: Staphylinidae), click beetles(Coleoptera: Elateridae), and earwigs (Dermaptera) have also beencited as important components of the D. saccharalis natural enemycomplex in Louisiana (Negm and Hensley, 1967, 1969).

Natural enemies of D. saccharalis are largely protected in Loui-siana sugarcane by the widespread use of tebufenozide, whichrepresented 90% of the foliar applications in 2007 (Pollet, 2008).This biorational insecticide belonging to the diacylhydrazine class isan ecdysone agonist that causes larvae to produce a malformedcuticle (Dhadialla et al., 1998). This compound is very specific tocertain lepidopterans (Dhadialla et al., 1998) and has shown little tono toxicity to D. saccharalis natural enemies (Reagan and Posey,2001). In addition to tebufenozide, the pyrethroids esfenvalerate,cyfluthrin, zeta-cypermethrin, lambda-cyhalothrin, and gamma-cyhalothrin are labeled but seldom used (Pollet, 2008). Because thedevelopment of resistance to different classes of insecticides in D.saccharalis populations has been a recurring problem in Louisiana

* Corresponding author. Tel.: þ1 225 578 1823; fax: þ1 225 578 1643.E-mail address: [email protected] (J.M. Beuzelin).

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journal homepage: www.elsevier .com/locate/cropro

0261-2194/$ e see front matter � 2010 Elsevier Ltd. All rights reserved.doi:10.1016/j.cropro.2010.06.004

Crop Protection 29 (2010) 1168e1176

19


sugarcane (Vines et al., 1984; Akbar et al., 2008), over-reliance ontebufenozide has raised concerns. Depending on cultivar andagricultural consultant recommendations, growers apply insecti-cides when the level of stalks infested with at least one live larvafeeding in the leaf sheaths exceeds a 5e10% threshold (Schexnayderet al., 2001; Posey et al., 2006). After field management failureswere reported, Reay-Jones et al. (2005) documented reductions insusceptibility to tebufenozide among D. saccharalis populations inLouisiana. Akbar et al. (2008) obtained a 27.1-fold increase in LC50after 12 generations of selection with tebufenozide in the labora-tory. Appropriate insecticide resistance management strategies aretherefore needed to preserve a balance of D. saccharalis controltactics for the Louisiana sugarcane industry.

Among potential alternatives to tebufenozide, novaluron isa biorational insecticide belonging to the benzoylphenyl urea classthat was initially registered in the USA in 2001 (Ishaaya andHorowitz, 1998; US EPA, 2001). Benzoylphenyl ureas inhibit chitinpolymerization, thus disrupting cuticle formation in immatureinsects (Oberlander and Silhacek, 1998). Novaluron is therefore notdirectly toxic to adult insects, but exerts insecticidal activity on eggand larval stages (Barzani, 2001). By 2008, this insecticide had beengranted permanent federal labels in the USA for use on cotton,potato, apple, Brassica vegetables, and ornamentals to control orsuppress caterpillars (Lepidoptera: Gracillariidae, Noctuidae, Plu-tellidae, Pyralidae, Tortricidae), hemipterans (Hemiptera: Aleyr-odidae, Miridae, Pentatomidae), beetles (Coleoptera:Chrysomelidae, Curculionidae), thrips (Thysanoptera: Thripidae),and leafminers (Diptera: Agromyzidae) (CPR, 2008; T&OR, 2008).Additionally, novaluron has a relatively low mammalian toxicity(Barzani, 2001).

In sugarcane, preliminary small-plot studies showed thatnovaluron reduced D. saccharalis infestations below economiclevels (Posey et al., 2003; Akbar et al., 2004). Targeting immaturestages, novaluron is expected to have limited non-target effects onadult natural enemies that are present in the sugarcane agro-ecosystem (Ishaaya et al., 2001, 2002). Thus, this biorationalpesticide has the potential to become a major component of Loui-siana sugarcane integrated pest management (IPM). In addition,having a different mode of action from other labeled insecticides,novaluron represents an alternative that would reduce the selec-tion pressure on D. saccharalis from other classes of insecticides,mitigating the potential development of insecticide resistance.Before novaluronwas granted a permanent federal label in 2009 foruse on sugarcane in the USA (www.greenbook.net, 2009), twoaerial application field studies were conducted in 2004 and 2007.These studies reported in this paper were conducted on commer-cial farms to assess the efficacy and non-target arthropod impactsof novaluron for D. saccharalismanagement in Louisiana sugarcane.

2. Material and methods

2.1. Experimental plots and D. saccharalis pest severityassessment e 2004

A study was conducted during the summer of 2004 near Che-neyville, Rapides Parish, LA (N 31.019�, W 92.302�) in commercialfields planted during the summer of 2003 with sugarcane cultivarLCP 85-384. Portions of fields were divided into 16 plots of 2 ha (30rows, 1.83-m row spacing) in a randomized complete block designarrangement with four blocks. Each plot was assigned one of fourtreatments. In addition to an untreated control, insecticide treat-ments were tebufenozide (Confirm� 2F) at 140 g(AI)/ha, andnovaluron (Diamond� 0.83EC) at 58 g(AI)/ha and 87 g(AI)/ha. Frommid-June, pre-treatment D. saccharalis infestation levels weredetermined byweekly examinations of 25 randomly selected stalks

from each block, observing for live larvae (1ste3rd instars) infest-ing leaf sheaths. The 5% threshold was exceeded on July 15 when10% of the stalks were infested and the first insecticide applicationwas made on July 16. All insecticide treatments were applied inwater with the surfactant Latron� CS-7 at the rate of 0.25% vol/vol.A Turbo Thrush Commander aircraft equipped with 38 CP-09-3Pnozzles (0.125 orifice, 30� deflector, 275.8 kPa pressure, CP ProductsInc., Tempe, AZ) and delivering 46.7 L per hectare of finishedformulation was used to spray swaths of 18.3 m at a speed ofapproximately 210 km/h. Subsequently, post-treatment infestationlevels were assessed in each plot on July 25, 30, August 5, 13, 21, 26,and September 2. All insecticides were applied again on August 13when a 10% threshold was exceeded in the high rate novaluronplots. Later infestation levels did not warrant a third insecticideapplication. At the end of the growing season, D. saccharalis injury(no. bored internodes/total no. internodes) and moth production(no. adult emergence holes) were recorded from 25 stalksrandomly selected in each plot on September 16.

2.2. Non-target arthropod pitfall trap sampling e 2004

Three pitfall traps were used to determine relative soil-associ-ated arthropod abundance in each plot. Traps consisted of widemouth 0.47-L glass jars (Ball Corp., Broomfield, CO) filled with150 ml of ethylene glycol and 2 ml of liquid soap to reduce surfacetension. Traps were placed on the 15th, 16th, and 15th row of eachplot, respectively 30, 60, and 90 m from the unplowed front. Pitfalltraps were imbedded to the soil surface and were covered by a 15by 15 cmmetal plate, whichwas supported by a tripod and elevated3 cm above the jar to exclude rain, debris, and larger animals. Pitfalltraps were initially placed in the experimental plots on June 11. Forpre-treatment sampling, traps were collected and replaced on July2 (21 days) and July 20 (18 days). For treatment assessment, trapswere collected and replaced on August 4 (15 days) and August 17(13 days). All traps were collected after a fifth sampling period onSeptember 2 (16 days). For each sampling period, the non-targetarthropods collected were counted after being sorted to thefollowing 13 groups: S. invicta, spiders, earwigs (Dermaptera: Ani-solabididae, Forficulidae), ground beetles, tiger beetles, clickbeetles, rove beetles, scarab beetles (Coleoptera: Scarabaeidae),other Coleoptera, field crickets (Orthoptera: Gryllidae), Orthopteraother than field crickets (Orthoptera: Gryllotalpidae, Tridactylidae),leafhoppers (Hemiptera: Cicadellidae), and other ground-dwellingarthropods. Predator abundance was determined considering fourgroups of predators: S. invicta, spiders, pooled predaceous beetles(ground, tiger, click, and rove), and earwigs. Non-predator abun-dance was determined considering four groups: field crickets,pooled non-predaceous beetles (scarab and others), leafhoppers,and pooled other arthropods (Orthoptera other than field cricketsand other ground-dwelling arthropods).

2.3. Experimental plots and D. saccharalis pest severityassessment e 2007

A study was conducted during the summer of 2007, nearBroussard, Iberia Parish, LA (N 30.068�, W 91.905�) in commercialfields planted during the summer of 2006 with sugarcane cultivarHoCP 96-540. Portions of fields were divided into 20 plots of 0.4 ha(12 rows, 1.83-m row spacing) in a randomized complete blockdesign arrangement with five blocks. Each plot was assigned oneof four treatments. In addition to an untreated control, insecticidetreatments were tebufenozide (Confirm� 2F) at 140 g(AI)/ha,novaluron (Diamond� 0.83EC) at 65 g(AI)/ha, and gamma-cyha-lothrin (Prolex� 1.25EC) at 20 g(AI)/ha. From mid-June, weeklyexaminations of 20 stalks per block indicated that the 5% threshold

J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e1176 1169

20


was exceeded on July 24 when 6.6% of the stalks were infestedwith at least one live D. saccharalis larva in the leaf sheaths.Insecticides were applied in water with the surfactant Latron� CS-7 (0.25% v/v) on July 26. A Robinson R44 helicopter equipped with36 TeeJet D6-46 nozzles directed 90� back (TeeJet Technologies,Wheaton, IL) was used to spray swaths of 10.97 m. The helicopterwas equipped with a flow meter calibrated to deliver 28.1 L perhectare of finished formulation regardless of ground speed. Post-treatment infestation levels were assessed in each plot on August8, 16, 24, and 31. Because the threshold was not exceeded in thenovaluron treated plots, there was no second insecticide applica-tion. At the end of the growing season, D. saccharalis injury (no.bored internodes/total no. internodes) and moth production (no.adult emergence holes) were recorded from 20 stalks randomlyselected in each plot on October 24.

2.4. Non-target arthropod pitfall trap sampling e 2007

Relative soil-associated arthropod abundance was determinedusing two pitfall traps per plot. The two pitfall traps were placed 38and 76 m from the front of each plot, on the 6th and 7th row,respectively. Traps were placed in plots on June 27, with pre-treatment sampling conducted from July 17 to 25 (8 days). Trapassessment of treatments was conducted from July 25 to August 8(14 days), August 8 to 31 (23 days), and August 31 to September 21(21 days). For each sampling period, the non-target arthropodscollected were counted after being sorted to 17 groups: S. invicta,ants other than S. invicta, spiders, earwigs, ground beetles,tiger beetles, click beetles, rove beetles, scarab beetles, otherColeoptera, field crickets, non-field cricket Orthoptera, leafhoppers,plant-hoppers (Hemiptera: Delphacidae), other Hemiptera(including Cercopidae), centipedes (class Chilopoda), and otherground-dwelling arthropods. Predator abundance was determinedconsidering the same four groups of predators as in the 2004experiment. Non-predator abundance was determined consideringfour groups: field crickets, pooled non-predaceous beetles (scaraband others), pooled hemipterans (leafhoppers, planthoppers, andother Hemiptera), and pooled other arthropods (ants other than S.invicta, Orthoptera other than field crickets, centipedes, and otherground-dwelling arthropods).

2.5. Data analyses

Each experiment was analyzed separately using Proc GLIMMIX(SAS Institute, 2008). Proportions of D. saccharalis infested stalksand bored internodes were analyzed using generalized linearmixedmodels with a binomial distribution and a logit link function.The number of moth emergence holes was analyzed using a one-way analysis of variance (ANOVA) with treatment as factor. Non-target arthropod count data, including pre-treatment observations,were divided by pitfall trap sampling period duration in days andanalyzed using a two-way ANOVA with treatment and samplingperiod as factors. Each pitfall trap was considered a sampling unit.Prior to ANOVA, moth production and non-target arthropod datawere transformed ð ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

xþ 0:5p Þ to normalize their distribution. A

variance component covariance structure was used to model theeffects of repeated measures for infestation levels and non-targetarthropod counts. The KenwardeRoger adjustment for denomi-nator degrees of freedom was used in all the models to correct forinexact F distributions. Least square means are reported for treat-ment effects, andwere separatedwith Tukey’s HSD (a¼ 0.05) whendifferences among treatments were detected. For the 2004 exper-iment, contrasts were also used to compare D. saccharalis injury(proportion of bored internodes) means from novaluron (low andhigh rates combined) vs. tebufenozide plots.

3. Results

3.1. D. saccharalis control e 2004 and 2007

Post-treatment D. saccharalis larval infestations were lower(P < 0.05) in insecticide treated plots relative to untreated plots inboth 2004 and 2007 (Table 1, Fig. 1). In 2004, differences amongtebufenozide and novaluron treated plots were not detected. Intreated plots, D. saccharalis infestations above the action thresholdof 5e10% of infested stalks were observed 28 days after the firstinsecticide application, warranting the second application onAugust 13. Infestations in untreated plots were above the thresholdfrom July 16, date of the first insecticide application, until the end ofthe season. Infestations changed over time (P < 0.05, Table 1), witha general increase observed over the growing season in untreatedplots, attaining a maximum of 25.6% of infested stalks on August 31.In insecticide treated plots, reduced D. saccharalis infestations wereobserved 8 and 13e15 days after each insecticide application(Fig. 1).

In 2007, differences in post-treatment D. saccharalis infestationsamong tebufenozide, novaluron, and gamma-cyhalothrin treatedplots were not detected, with infestations remaining below theaction threshold of 5e10% after the first insecticide applications.Infestations in untreated plots were near or above the actionthreshold of 5e10% from July 26, date of the first insecticideapplications, until the end of the season. Post-treatment D. sac-charalis infestations did not differ in time (P > 0.05, Table 1);however, a trend for an increase was observed over the growingseason in untreated plots (Fig. 1).

Untreated plots had the highest end of season D. saccharalisinjury with 12.6 and 7.8% bored internodes in 2004 and 2007,respectively (Table 1, Fig. 2). In 2004, a reduction (8.6-fold) in injurywas observed in plots treated with the low rate of novaluron. Anumerical trend for a decrease in bored internodes was observed inplots treated with tebufenozide (2.9-fold) and novaluron high rate(6.3-fold) (Fig. 2). In addition, contrasts comparing novalurontreated plots with those treated with tebufenozide (F¼ 6.56; df¼ 1,8.24; P ¼ 0.033) showed that novaluron was associated with lowerD. saccharalis injury than tebufenozide. Differences in D. saccharalismoth production associated with insecticide treatments (Fig. 2)were not detected (Table 1).

In 2007, reductions in injury were observed in plots treated withtebufenozide (8.0-fold) and novaluron (14.5-fold). Only a numericaltrend for a decrease (3.1-fold) in D. saccharalis bored internodeswas observed in plots treated with gamma-cyhalothrin. A numer-ical trend for a decrease (3.4-fold) in D. saccharalismoth emergenceholes was also recorded in plots treated with gamma-cyhalothrin(Fig. 2). Whereas moth emergence holes averaged 0.37 per stalk inuntreated plots, moth production was reduced (P < 0.05) in plotstreated with tebufenozide (9.3-fold). Moth emergence holes werenot observed in stalk samples from novaluron treated plots (Fig. 2).

3.2. Non-target arthropod assessment, 2004

Non-target arthropod abundances did not differ (P > 0.05)among insecticide treated and untreated plots (Table 2). However,differences among sampling periods (P < 0.05) were detected forseveral soil-associated arthropod groups, as well as significanttreatment by sampling period interactions (P < 0.05) (Table 2).Spider abundance differed among sampling periods extendingfrom mid-June to early September, with no treatment by samplingperiod interactions detected. Prior to insecticide applications,spider abundance decreased (1.4-fold) between the first andsecond sampling periods. After the first insecticide applications,spider abundance increased (1.5-fold) between the second and

J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e11761170

21


fourth sampling period, and then decreased (1.5-fold) during thefifth period.

Predaceous beetle abundance decreased over the five pitfall trapsampling periods. However, as shown by the significant treatmentby sampling period interaction, abundances were stable in plotstreated with tebufenozide and novaluron high rate, whereasa decrease was observed in novaluron low rate and untreated plots(Fig. 3). When considering each sampling period separately,predaceous beetle abundances among treatments were notdifferent. For other beetles, field crickets, and leafhoppers, abun-dances differed among sampling periods, with no treatment bysampling period interactions detected (Table 2). Non-predaceousbeetle abundance decreased (3.3-fold) prior to insecticide appli-cations between the first and second sampling periods, and was

stable during the remaining sampling periods. Overall field cricketand leafhopper abundances increased (6.6-fold and 33.7-fold,respectively) from mid-June to early September, with lowestabundances observed prior to the first insecticide applications.Abundance of other arthropods increased (4.7-fold) over the fivepitfall trap sampling periods. However, as shown by the significanttreatment by sampling period interaction, changes in abundancebetween the second, third, and fourth sampling periods in nova-luron low rate plots (increase followed by decrease) were differentfrom those observed in novaluron high rate plots (decrease fol-lowed by increase). When considering each sampling periodseparately, the abundance of other arthropods among treatmentswas not significantly different.

3.3. Non-target arthropod assessment e 2007

Except for predaceous beetles, non-target arthropod abun-dances did not differ (P > 0.05) among untreated and insecticidetreated plots (Table 2). In comparison to untreated plots, a 1.5-foldlower predaceous beetle abundance was observed in plots treatedwith gamma-cyhalothrin. Predaceous beetle abundances in plotstreated with novaluron and tebufenozide were not different fromthose in either untreated or gamma-cyhalothrin treated plots. Anoverall decrease in abundance over the growing season was alsoobserved (Fig. 3).

For several other soil-associated arthropod groups, differencesamong sampling periods were detected (P < 0.05), as well assignificant treatment by period interactions (P< 0.05) (Table 2). ForS. invicta and spiders, abundances decreased throughout the fourpitfall trap sampling periods extending from mid-July to mid-September, 2.4-fold and 6.9-fold, respectively. Adult cricket abun-dance differed among sampling periods, with more adult cricketscollected during the fourth sampling period than during thesecond. However, a significant treatment by sampling periodinteraction was detected. Whereas adult cricket abundanceremained relatively stable in tebufenozide and novaluron treatedplots, a numerical trend for a decrease (11.9-fold) between the firstand second sampling, and a significant increase (13.5-fold) from thesecond to the fourth sampling were observed in gamma-cyhalo-thrin treated plots. A similar pattern was observed in untreatedplots although differences among periods were not detected.Whenconsidering each sampling period separately, adult cricket abun-dances among treatments were not different. Immature cricketabundance increased (1.7-fold) between the first and third pitfalltrap sampling periods (Fig. 4). However, a significant treatment bysampling period interaction was detected. From the first to thethird sampling period, a significant increase (4.9-fold) in immaturecrickets was observed in untreated plots, whereas therewas a trendfor a decrease from the second to the third sampling in novaluron(1.5-fold) and gamma-cyhalothrin (1.3-fold) treated plots. The totalnumber of field crickets in pitfall traps had the same pattern amongsampling dates and treatments as immatures, which represented81, 91, 90, and 77% of the crickets collected over the four samplingperiods, respectively. For hemipterans, pitfall trap catches

Table 1Statistical comparisons of insecticide efficacy from on-farm aerial application experiments on sugarcane in Louisiana, 2004 and 2007.

2004 2007

F df P > F F df P > F

Post-treatment D. saccharalis larval infestations Treatment 23.42 3, 7.18 <0.001 11.94 3, 63 <0.001Date 2.68 6, 22.69 0.041 0.93 3, 63 0.432Treatment � Date 1.20 18, 25.26 0.332 0.87 9, 63 0.561

End of season D. saccharalis injury Treatment 4.07 3, 9.09 0.044 12.89 3, 5.98 0.005D. saccharalis moth production Treatment 1.17 3, 9 0.375 5.41 3, 12 0.014

Fig. 1. Post-treatment levels of live D. saccharalis larval infestations (LSMeans � SEM)in the leaf sheath of sugarcane from insecticide aerial application experiments inLouisiana, 2004 and 2007.


22


increased (10.5-fold) between the first and third sampling periods,before decreasing (3.1-fold) during the fourth period.

4. Discussion

4.1. Insecticide efficacy

Aerial applications of the biorational insecticides tebufenozideand novaluron effectively reduced D. saccharalis larval infestationsin sugarcane. Both insecticides also reduced end of season injurybased on D. saccharalis bored internodes, although not alwayssignificant at a ¼ 0.05. Our on-farm study showed that underconditions consistent with Louisiana production practices, thechitin synthesis inhibitor novaluron decreased D. saccharalisinfestations and injury, with efficacy levels equal to or better thanthose of tebufenozide. Sugarcane growers traditionally accept D.saccharalis injury levels at harvest below 10% bored internodes.Although sugarcane tolerance to injury differs with cultivar, Whiteet al. (2008) determined that each 1% bored internode injuryresulted in an average loss of 0.6% in sugar produced per hectare.

Because a strong association exists between yield losses andD. saccharalis injury expressed as % bored internodes (White et al.,2008), yield data were not collected in our study. Whereas boredinternodes represent injury causing yield losses, moth emergenceholes estimate D. saccharalis adult production (Bessin et al., 1990)and document the efficacy of insecticides in decreasing pest pop-ulations produced by the infested crop. Although tebufenozide andnovaluron had no measurable effects on D. saccharalis adultproduction in 2004, moth emergence hole data collected in 2007provided some evidence that the biorational insecticides coulddecrease areawide pest populations in addition to protecting yields.

Data on post-treatment larval infestations, end of season injury,and moth emergence holes collectively suggest that the pyrethroid,gamma-cyhalothrin, was less efficacious than the biorationalinsecticides in protecting sugarcane from D. saccharalis. However,this pyrethroid was studied only during one growing season.Gamma-cyhalothrin is the active insecticidal isomer of lambda-cyhalothrin. Lambda-cyhalothrin (Karate� 1EC or Karate� Z 2.08EC)was compared to tebufenozide in five previous studies assessingthe efficacy of aerially applied insecticides for D. saccharalis

A

B

Fig. 2. (A) End of season D. saccharalis bored internodes (LSMeans � SEM) and (B) adult emergence (LSMeans � SEM) from insecticide aerial application experiments on sugarcanein Louisiana, 2004 and 2007. Bars within each chart followed by the same letter are not significantly different (P > 0.05, Tukey’s HSD).


23


management in sugarcane (Rodriguez et al., 1995, 1998;Schexnayder et al., 1999; Posey and Reagan, 2000; McAllisteret al., 2002). In all five studies, decreases in percent bored inter-nodes below economic levels were associated with lambda-cyha-lothrin, showing that this pyrethroid was suitable for D. saccharalismanagement. D. saccharalis injury reductions associated withlambda-cyhalothrin were not different (P > 0.05) from thoseassociated with tebufenozide although numerically lower in all butone study (McAllister et al., 2002). Although it deserves furtherstudy, gamma-cyhalothrin also seems suitable for managing D.saccharalis below economic levels despite a possible lower efficacycompared to the biorational insecticides.

4.2. Non-target arthropod impact

S. invicta plays a central role in Louisiana sugarcane IPM bysuppressing D. saccharalis populations (Negm and Hensley, 1967,1969; Beuzelin et al., 2009). In our study, no disruptive effects onS. invictawere observed in associationwith insecticide applications.Spiders are also key D. saccharalis predators (Ali and Reagan, 1986),and because their pitfall trap samples have limited spatial andtemporal variability, these arthropods have been used as an indi-cator group in insecticide non-target assessment (Reagan andPosey, 2001). No major disruptive effects on spiders and otherpredaceous non-target arthropods were observed in associationwith insecticide applications reported in our study. Nevertheless,predaceous beetles may have been affected by aerial applications ofgamma-cyhalothrin in 2007. However, because a numerical trendfor more abundant (2.3-fold) predaceous beetles was observed incontrol plots during the pre-treatment sampling period, differential

abundances might have been caused by the initial distribution ofbeetles among plots.

Non-predaceous arthropods are also involved in the balance ofthe sugarcane agroecosystem. For instance, crickets, which havebeen used as an indicator group in non-target assessment, areimportant as food for S. invicta (Reagan, 2001). No major negativeimpacts on non-predaceous arthropods were associated withinsecticide applications reported in our study. Nevertheless, ourdata suggest that immature crickets might have been affected bynovaluron and gamma-cyhalothrin applications in 2007. Direct orresidual contact with novaluron, as well as ingestion of novaluron-exposed plant material, may disrupt cricket development toadulthood and kill immatures. Exposure to broad-spectrumgamma-cyhalothrin may also increase the mortality of smaller andmore susceptible crickets. However, non-target assessment forimmature crickets was conducted only in 2007, not allowinga generalization of the results.

Tebufenozide has been shown to be exceptionally safe to non-target arthropods in both laboratory (e.g., Smagghe and Degheele,1995; Medina et al., 2003) and field studies (e.g., Butler et al.,1997; Gurr et al., 1999; Reagan and Posey, 2001). In our study,this ecdysone agonist had no measurable effects on the abundanceof non-target arthropods. Among four previous insecticide aerialapplication sugarcane studies, tebufenozide was associated oncewith decreased ground beetles and pygmy mole crickets, but hasnever suppressed other non-target arthropods (Woolwine et al.,1995, 1997, 1998; McAllister et al., 2002).

Gamma-cyhalothrin aerial applications were conducted for thefirst time in 2007 for D. saccharalis management, and possiblelimited non-target effects on predaceous beetles and immature

Table 2Statistical comparisons of the abundance of selected non-target arthropods from continuous pitfall trap sampling in sugarcane plots from on-farm insecticide aerial applicationexperiments in Louisiana, 2004 and 2007.

2004 2007

F df P > F F df P > F

S. invicta Treatment 0.77 3, 9 0.540 0.22 3, 141 0.882Period 1.86 4, 176 0.120 4.00 3, 141 0.009Treatment � Period 1.41 12, 176 0.166 0.50 9, 141 0.872

Spiders Treatment 0.56 3, 12 0.649 0.89 3, 31.3 0.458Period 6.08 4, 176 <0.001 46.59 3, 105 <0.001Treatment � Period 1.08 12, 176 0.382 1.06 9, 105 0.398

Predaceous beetles Treatment 0.14 3, 12 0.936 3.20 3, 32.6 0.036Period 7.81 4, 176 <0.001 25.97 3, 106 <0.001Treatment � Period 1.92 12, 176 0.035 1.04 9, 106 0.413

Earwigs Treatment 1.43 3, 9.01 0.296 2.10 3, 32.6 0.119Period 0.73 4, 208 0.575 0.11 3, 107 0.953Treatment � Period 1.45 12, 208 0.147 1.36 9, 107 0.218

Adult field crickets Treatment e e e 0.80 3, 11.8 0.516Period e e e 3.12 3, 125 0.029Treatment � Period e e e 2.28 9, 125 0.021

Immature field crickets Treatment e e e 0.28 3, 11.6 0.840Period e e e 3.18 3, 105 0.027Treatment� Period e e e 2.09 9, 105 0.037

Field crickets Treatment 0.06 3, 9 0.979 0.26 3, 11.5 0.853Period 57.12 4, 176 <0.001 1.90 3, 105 0.135Treatment� Period 0.79 12, 176 0.658 2.34 9, 105 0.019

Non-predaceous beetles Treatment 0.20 3, 9 0.894 0.56 3, 137 0.645Period 10.01 4, 176 <0.001 1.34 3, 137 0.263Treatment� Period 0.60 12, 176 0.844 0.85 9, 137 0.571

Hemipterans Treatment e e e 1.75 3, 11.1 0.215Period e e e 73.63 3, 104 <0.001Treatment� Period e e e 1.12 9, 104 0.352

Leafhoppers Treatment 1.33 3, 12 0.312 e e e

Period 21.53 4, 176 <0.001 e e e

Treatment � Period 1.28 12, 176 0.232 e e e

Other arthropods Treatment 0.25 3, 9 0.857 0.66 3, 16.1 0.588Period 30.36 4, 208 <0.001 0.65 3, 126 0.585Treatment � Period 2.09 12, 208 0.019 0.63 9, 126 0.769


24


crickets were observed. Gamma-cyhalothrin was expected to havenon-target impacts similar to those of lambda-cyhalothrin. Inprevious large plot aerial application studies conducted on sugar-cane, Woolwine et al. (1997, 1998) did not detect non-target effectsassociated with lambda-cyhalothrin. However, Woolwine et al.(1995) and McAllister et al. (2002) reported deleterious non-target effects on spiders and S. invicta, respectively. Pyrethroidformulations, emulsifiable concentrate or encapsulated, variedamong studies and may have impacted non-target selectivity(Pogoda et al., 2001). Negative impacts of lambda-cyhalothrin onfield populations of non-target arthropods, although oftentemporary, have also been reported in several other agro-ecosystems (e.g., Pilling and Kedwards, 1996; Al-Deeb et al., 2001;Musser and Shelton, 2003). In addition to previous data onlambda-cyhalothrin, our study suggests possible non-target effectsfor gamma-cyhalothrin that warrant a more judicious use of thisinsecticide.

Novaluron had no measurable negative effects on non-targetarthropods observed in our study, although limited non-targeteffects may have occurred on immature crickets (trend for a 1.5-

fold reduction over a 3-week period). Novaluron is consideredrelatively safe for beneficial arthropods in cotton agroecosystems(Ishaaya et al., 2001) and in greenhouses (Ishaaya et al., 2002).However, laboratory bioassays suggested that all life stages ofPodisus maculiventris (Say) (Hemiptera: Pentatomidae), a beneficialpredaceous non-target arthropod in potato (Solanum tuberosum L.)fields, were susceptible to novaluron, with both lethal and sublethaleffects (Cutler et al., 2006). In laboratory bioassays, novalurondecreased the emergence rates of Trichogramma parasitoids (Bastoset al., 2006). Despite these non-target effects, novaluron seemedmore compatible with biological control using Trichogrammawaspsthan organophosphate, carbamate, and pyrethroid insecticides(Bastos et al., 2006). In addition to data available in the scientificliterature, our study suggests that the use of novaluron for D. sac-charalis management in sugarcane is compatible with the conser-vation of most soil-associated non-target arthropod groups.

4.3. Methodological limitations

Our on-farm study documented the efficacy of aerial applica-tions of insecticides that mimicked commercial production prac-tices, yielding results with direct practical implications comparedto laboratory or small-plot experiments. Plot size (�0.4 ha) mini-mized insecticide drift and arthropod movement from one plot toanother. Our study also documented soil-associated non-targetarthropod abundance using continuous pitfall trap sampling. Esti-mates of arthropod abundance using pitfall traps vary with abso-lute population size, but also with arthropod activity and habitatstructure (Southwood andHenderson, 2000). Insecticidesmay alterarthropod activity and bias trap catches in ways not reflectingchanges in the functional roles of arthropod populations. Our studydid not assess the potential sublethal and long-term non-targeteffects of the insecticides.

Pitfall trap estimates for most soil-associated arthropod groupswere highly variable, making consistent patterns and differencesdifficult to detect. Pre-treatment sampling was included in ouranalyses, with the effect of insecticide applications expected to bedetected with significant treatment by sampling period interac-tions. However, the detected interactions showed that observedtreatment effects were not always consistent across sampling

Fig. 3. Relative abundance of predaceous beetles from continuous pitfall trap samplingin sugarcane plots of insecticide aerial application experiments in Louisiana, 2004 and2007. Arrows represent dates of insecticide applications. Bars within each chart fol-lowed by the same letter are not significantly different (P > 0.05, Tukey’s HSD).

Fig. 4. Relative abundance of immature field crickets from continuous pitfall trapsampling in sugarcane plots of insecticide aerial application experiments in Louisiana,2007. The arrow represents the date of insecticide applications. Bars followed by thesame letter are not significantly different (P > 0.05, Tukey’s HSD).


25


periods. No broad-spectrum insecticides with documentedconsistent non-target effects were used in our study, as suchchemistry is no longer recommended. For experimental purposes,future studies should include a broad-spectrum insecticide to allowfor a better comparison with biorational insecticides. Using indexcards soaked in peanut oil in addition to pitfall traps (Ali andReagan, 1985) for S. invicta abundance estimation may alsoimprove non-target assessment for this group.

4.4. Concluding remarks

With a better understanding of ecological interactions occurringin the agroecosystem and the use of effective but narrow-rangechemistry, considerable advances have been made over nearly fivedecades of Louisiana sugarcane IPM (Hensley, 1971; Reagan, 2001).However, in conjunction with the widespread use of D. saccharalis-susceptible sugarcane cultivars, insecticides remain the primarytool for D. saccharalis management when infestations approacheconomically damaging levels (Reay-Jones et al., 2005). Numerousinsecticides have been effective in reducing D. saccharalis infesta-tions in sugarcane, but many of these insecticides were subse-quently abandoned due to either the development of resistance orenvironmental issues (Vines et al., 1984; Southwick et al., 1995). Forover a decade, sugarcane growers have had only pyrethroids anda diacylhydrazine available, and need a more diverse array oflabeled chemicals. Novaluron appears to fit well in sugarcane IPM.This chemical provides control of economically damaging infesta-tions when employing recommended application timing and actionthreshold, and also has selectivity characteristics favorable tonatural enemies. Novaluron received a permanent federal label foruse on sugarcane in the USA during the 2009 growing season(www.greenbook.net, 2009), providing a needed alternative totebufenozide to which D. saccharalis populations have begun toexhibit resistance. Future research will continue to include moni-toring D. saccharalis resistance to tebufenozide and potential cross-resistance with novaluron, but also non-target effects that mightnot have been detected during the on-farm experiments of 2004and 2007.

Acknowledgements

This work was supported by grants from the American SugarCane League, the Environmental Protection Agency Strategic Agri-cultural Initiative Program and various insecticide companies. Wethank Grady Coburn (Pest Management Enterprises, Inc.) andBlaine Viator (Calvin Viator, Ph.D. and Associates, LLC) for technicalassistance. We thank J.A. Davis, A.M. Hammond, M.J. Stout, and J.H.Temple (Louisiana State University) for their review of the manu-script. This paper is approved for publication by the Director of theLouisiana Agricultural Experiment Station as manuscript number2009-234-4013.

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27

COMMUNITY AND ECOSYSTEM ECOLOGY

Seasonal Infestations of Two Stem Borers (Lepidoptera: Crambidae)in Non-Crop Grasses of Gulf Coast Rice Agroecosystems

J. M. BEUZELIN,1 A. MESZAROS, T. E. REAGAN, L. T. WILSON,2 M. O. WAY,2

D. C. BLOUIN,3 AND A. T. SHOWLER4

Department of Entomology, Louisiana Agricultural Experiment Station, Louisiana State;University Agricultural Center, Baton Rouge, LA 70803

Environ. Entomol. 40(5): 000Ð000 (2011); DOI: 10.1603/EN11044

ABSTRACT Infestations of two stem borers, Eoreuma loftini (Dyar) and Diatraea saccharalis (F.)(Lepidoptera:Crambidae),werecompared innoncropgrasses adjacent to rice(Oryza sativaL.)Þelds.Three farms in the Texas rice Gulf Coast production area were surveyed every 6Ð8 wk between 2007and 2009 by using quadrat sampling along transects. AlthoughD. saccharalis densities were relativelylow, E. loftini average densities ranged from 0.3 to 5.7 immatures per m2 throughout the 2-yr period.Early annual grasses including ryegrass, Lolium spp., and brome, Bromus spp., were infested duringthe spring, whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and VaseyÕs grass,Paspalumurvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host(41Ð78% relative abundance), but VaseyÕs grass (13Ð40% relative abundance) harbored as much as 62%of the recovered E. loftini immatures (during the winter). Young rice in newly planted Þelds did nothost stem borers before June. April sampling in fallow rice Þelds showed that any available live grassmaterial, volunteer rice or weed, can serve as a host during the spring. Our study suggests that noncropgrasses are year-round sources of E. loftini in Texas rice agroecosystems and may increase pestpopulations.

KEY WORDS Mexican rice borer, Eoreuma loftini (Dyar), sugarcane borer, Diatraea saccharalis(F.), alternate hosts

Eoreuma loftini (Dyar) and Diatraea saccharalis (F.)(Lepidoptera: Crambidae) are stem boring pests ofsugarcane (hybrids of Saccharum spp.), rice (OryzasativaL.), corn (ZeamaysL.), and sorghum [Sorghumbicolor (L.) Moench] crops in the Gulf Coast region(Long and Hensley 1972, Johnson 1984). AlthoughD.saccharalis has been established in the southeasternUnited States since the 1850s (Stubbs and Morgan1902), E. loftini has expanded its range in a northeast-erly direction since its Þrst detection in south Texas in1980 (Reay-Jones et al. 2007). E. loftini was reportedin 2008 for the Þrst time in Louisiana (Hummel et al.2010), where annual economic losses in sugarcane andrice may become as severe as $250 million within thenext decades (Reay-Jones et al. 2008).

In addition to crop hosts, Van Zwaluwenburg(1926) observed that E. loftini “attacks practically allthe grasses large enough to afford it shelter within the

stalk.” E. loftini has been collected from numerousgrasses (Poaceae), Canna spp. (Cannaceae), and bul-rush (Cyperaceae: Scirpus validus Vahl) (Osborn andPhillips 1946, Johnson 1984, Showler et al. 2011). D.saccharalis larvae also feed on a range of noncropgrasses comparable to that reported for E. loftini(Jones and Bradley 1924, Holloway et al. 1928, Box1956, Bessin and Reagan 1990). Beuzelin et al. (2010),by using potted sentinel plants grown under naturalinfestations, conÞrmed that a number of Gulf Coastregion noncrop grasses were hosts for both E. loftiniand D. saccharalis. Amazon sprangletop [Leptochloapanicoides (Presl) Hitch], a common weed in riceÞelds, was a highly suitable host, harboring the higheststem borer infestations with �75% of the plants in-fested with at least one larva. Johnsongrass [Sorghumhalepense (L.) Pers.] and VaseyÕs grass (Paspalum ur-villei Steud.), two ubiquitous perennial grasses, alsosupported complete larval development of both spe-cies. In contrast, broadleaf signalgrass [Urochloa platy-phylla (Munro ex C. Wright) R.D. Webster], a com-mon weed near rice Þelds, proved to be a poor stemborer host (Beuzelin et al. 2010, Showler et al. 2011).

In agroecosystems, the effects of vegetation diver-sity on arthropod population dynamics are complexand variable (Andow 1991, Norris and Kogan 2005).

1 Corresponding author, e-mail: [email protected] Texas A&M AgriLife Research and Extension Center at Beau-

mont, Texas A&M University, Beaumont, TX 77713.3 Department of Experimental Statistics, Louisiana Agricultural Ex-

periment Station, Louisiana State University Agricultural Center, Ba-ton Rouge, LA 70803.

4 USDAÐARS, Kika de la Garza Subtropical Agricultural ResearchCenter, Weslaco, TX 78596.

0046-225X/11/0000Ð0000$04.00/0 � 2011 Entomological Society of America

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Nearby plants may increase habitat availability forpredators and offer additional shelter and food fortheir prey, thus increasing natural enemy density andsubsequently decreasing insect pest populations (Le-tourneau 1987, Russell 1989). Conversely, nearbyplants may increase plant host availability and releaseadditional host-Þnding stimuli for insect pests, thusenhancing pest populations (Karban 1997, Tindall etal. 2004). Previous studies have suggested that non-crop hosts could play a key role in E. loftini and D.saccharalis population dynamics in Gulf Coast agro-ecosystems (Beuzelin et al. 2010, Showler et al. 2011).However, the quantiÞcation of noncrop host presenceand use has been limited, especially when crop hostsare absent or too young to sustain stem borer devel-opment. In this study, surveys were conducted toquantify the seasonal abundance of E. loftini, D. sac-charalis, and their noncrop hosts in Þeld margins andsurrounding habitats of Texas rice agroecosystems.

Materials and Methods

Transect Sampling in Noncrop Habitats. Threefarms were surveyed in the Texas Gulf Coast riceproduction area (Jefferson County, 30.059� N, 94.279�W; Chambers County, 29.855� N, 94.544� W; and Jack-son County, 29.027� N, 96.439� W). These farms weresampled every 6Ð8 wk for 2 yr (April 2007-February2008, April 2008-February 2009). For each year, twotransects were located along noncultivated Þeld mar-gins, roadsides, or ditches on each farm. Transectsaveraged 564 � 63 (SE) m in length and were within250Ð500 m of the closest rice Þelds. The minimum andmaximum distances between two transects on a farmin a year averaged 302 � 142 (SE) and 1026 � 210 (SE)m, respectively. The average distance between thecenters of two transects was 678 � 169 (SE) m. Oneach sampling date (Fig. 1), three representative lo-cations per transect were sampled, with three 1-m2

quadrats randomly selected within 10 m of the centerof each location. If sections of transects were mowedby rice producers during the growing season (MarchÐAugust), they were excluded from sampling for at leasttwo consecutive sampling dates. If sections weremowed during the postseason or winter, when plantgrowth is the slowest, they were permanently ex-cluded from sampling.

For each quadrat, all grass-like plants, hereafterreferred to as graminoids, were cut at the soil surfacelevel and placed in 50-liter plastic bags. Bags werestored at the Texas A&M AgriLife Research and Ex-tension Center at Beaumont, TX, in a cold room at13Ð15�C and processed within 1 wk. Noncrop gramin-oids present in each quadrat were identiÞed to genusor species, and their relative abundance was visuallyestimated per volume of sampled plant material. Thenumber of tillers for each graminoid was recorded,except during the Þrst two sampling dates in the Þrstyear of the study. During the second year of the study(April 2008-February 2009), average tiller size (frombase to farthest tip) was determined for each gramin-oid in each quadrat from all (if tillers �4) or fourrandomly selected tillers. Average tiller stem diameter(as measured � 1 cm below the Þrst apparent node,or � 3 cm above the cut if no node present) was alsodetermined. For tillers with ßattened stems, the av-erage between the major and minor stem diameterswas recorded. During the second year of the study,plant phenology was determined visually as the pro-portion of plant material that was vegetatively grow-ing, ßowering, mature, senescent, and dead.

All graminoids collected from the quadrats werevisually examined for stem borer feeding injury. Whena discoloration of the leaf sheath or a hole in the stemwas observed, injured plants were dissected to recoverE. loftini andD. saccharalis larvae and pupae, hereafterreferred to as immatures. Immatures were sight-iden-tiÞed using characters reported in Browning et al.

Fig. 1. (A) E. loftini and (B) D. saccharalis immature densities (LS means) in noncrop habitats adjacent to rice Þeldsin Texas, 2007Ð2009. Total immatures are the sum of all larvae and pupae. Error bars represent � SE for total immatures LSmeans.

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(1989), Legaspi et al. (1997), and Solis (1999). For the0Ð6% and 0Ð12% ofE. loftini andD. saccharalis larvae,respectively, that were recovered in bags on eachsampling date because they had crawled out ofgraminoid stems during sample transportation or stor-age, the original host plant was also determined. Whena quadrat sample was comprised of a single graminoid,larvae recovered in the bag were attributed to thatgraminoid. When several graminoids were in a quadratsample, larvae were attributed to a host plant based onobserved injury. The size of larvae was visually de-termined, with small, medium-sized, and large larvaecorresponding approximately to Þrst and second,third, and fourth and Þfth instars, respectively. De-pendent on the number of immatures recovered oneach sampling date, 10Ð60 randomly selectedE. loftiniandD. saccharalis immatures were reared on artiÞcialdiet (Southland Product Inc., Lake Village, AR) untiladult eclosion to conÞrm species identiÞcation (Klots1970, Legaspi et al. 1997).Transect Sampling in Rice Habitats. During the

early April sampling date of each year of the study, onefallowed rice Þeld was selected and sampled on eachfarm to verify whether old rice stubble could host E.loftini and D. saccharalis. Fallowed rice Þelds weredirectly adjacent (�35 m) to one noncrop habitattransect for at least one-third of the length of thattransect, or were within 50 m of the end of one non-crop habitat transect. In addition, one rice Þeldplanted between March and May was selected andsampled each year on each farm in early April, lateMay, and late June to verify whether newly plantedrice could host stem borers. Newly planted rice Þeldswere directly adjacent (�35 m) to one noncrop hab-itat transect for at least one-third of the length of thattransect. For each fallowed and newly planted riceÞeld, one transect was drawn and Þve (2007) or three(2008) sampling zones with three 1-m2 quadrats ineach were sampled for stem borer injury and imma-ture presence.Adult Stem Borer Trapping. E. loftini and D. sac-

charalis moths were trapped on each farm near thecenter of each noncrop habitat transect for 7Ð14 dafter transect sampling during the spring, summer, andfall. After the December and February transect sam-pling of noncrop habitats, moth trapping averaged 33and 15 d, respectively, because of reduced accessibil-ity to trapping locations. Two traps per transect, onefor E. loftini and one for D. saccharalis, were posi-tioned �10 m apart and placed 1.5 m above the soilsurface on a metal pole. Bucket traps (Unitrap, GreatLakes IPM, Vestaburg, MI) were used for E. loftinimoth monitoring. Each trap was baited with a syn-thetic female E. loftini sex pheromone lure (Luresept,Hercon Environmental, Emigsville, PA) and con-tained an insecticidal strip (Vaportape II, Hercon En-vironmental, Emigsville, PA). Sticky wing traps(Pherocon 1C Trap, Trece Inc., Adair, OK) were usedfor D. saccharalis moth monitoring. Each trap wasbaited with two D. saccharalis female pupae nearingadult eclosion. D. saccharalis female pupae from lab-oratory rearing were provided by the USDA-ARS Sug-

arcane Research Unit, Houma, LA (Þrst year of thestudy) and the LSU AgCenter Rice Entomology Lab-oratory, Baton Rouge, LA (second year of the study).Trap catches were adjusted by the length of the sam-pling period to express moth abundance on a mothsper trap per day basis.Data Analyses. All univariate statistical analyses

were conducted using linear mixed models in ProcGLIMMIX (SAS Institute 2008). The KenwardÐRogeradjustment for denominator degrees of freedom wasused in all models to correct for inexactFdistributions.Unless stated otherwise, least square means � stan-dard errors from the LSMEANS statement output(Proc GLIMMIX, SAS Institute 2008) are reported.When Þxed effects were detected (P� 0.05), TukeyÕshonestly signiÞcant difference (HSD) (� � 0.05) wasused toassist in the interpretationofobservedpatternsand differences in least square means. E. loftini andD.saccharalis densities (number of immatures per m2)were compared using univariate models with year,date, and year � date as Þxed effects. Farm, farm �year, transect(farm � year), date � transect(farm �year), and location(date � transect farm � year) wererandom effects.

Relative abundance was recorded simultaneouslyfor numerous graminoids from the same observationunits (i.e., quadrat). Thus, before univariate analyses,multivariate analyses including the 12 most prevalentgraminoids (Table 1) were conducted using ProcGLM (SAS Institute 2008) with a MANOVA state-ment. Multivariate and univariate analyses includedthe same Þxed and random effects as for stem borerdensity comparisons. Graminoid tiller densities werecompared using the same method as for plant relativeabundance analyses. Tiller size and stem diameter,which were recorded during the second year of thestudy, were each compared using univariate modelswith date as Þxed effect and farm, transect(farm),date � transect(farm), and location(date � transectfarm) as random effects.

For each of the six graminoids consistently infestedwith stem borers (Table 2), percentages of recoveredE. loftini as affected by year and date were compared.By transect and sampling date, the percentage of re-covered E. loftini in a selected graminoid was com-puted as the sum of E. loftini collected from thatselected plant multiplied by 100 and divided by thesum of E. loftini collected from all plants. When E.loftiniwerenotcollected froma transectona samplingdate, percentages of recovered E. loftini were notcomputed. In addition, when a graminoid was notrecorded from a transect, the percentage of recoveredE. loftini was considered zero. A multivariate analysisincluding the six graminoids consistently infested withstem borers was conducted before univariate analyses.Fixed effects for the multivariate model (Proc GLMwith MANOVA statement, SAS Institute 2008) wereyear, date, and year � date whereas random effectswere farm, farm � year, and transect(farm � year).Each univariate model for each graminoid shared thesame Þxed and random effects as the multivariatemodel. For each of the two most prevalent graminoids

October 2011 BEUZELIN ET AL.: STEM BORER INFESTATIONS IN NON-CROP GRASSES 3


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consistently infested with E. loftini, the percentage ofrecoveredE. loftini per percent of plant relative abun-dance was determined. By transect and sampling date,it was computed as the percentage of recovered E.loftini in a selected graminoid divided by the averagerelative abundance for that selected plant. Only uni-variate analyses comparing percentages of recoveredE. loftini per percent of plant relative abundance asaffected by year and date were conducted (samemodel as for percentage of recovered E. loftini anal-ysis).

The percentage of recovered D. saccharalis andrecovered D. saccharalis per percent of plant relativeabundance were computed using the same method asfor E. loftini. Because D. saccharalis infestations were

recovered almost exclusively from the two most prev-alent graminoid species, only univariate analyses com-paring year and date for these two plant species wereconducted (same model as for proportion of recov-ered E. loftini analysis). E. loftini and D. saccharalismoth trap catches as affected by year and date werealso compared using the same univariate models.

Results

Eoreuma loftini and D. saccharalis Infestations inNoncrop Habitats. E. loftini larvae and pupae wererecorded in noncrop habitats during each samplingdate (Fig. 1A). There was a numerical trend (F� 8.78;df � 1, 2.0; P � 0.097) with 2.5-fold greater E. loftini

Table 1. Statistical comparisons for abundance and size estimates of 12 grasses commonly found in non-crop habitats adjacent to ricefields, Texas, 2007–2009

PlantRelative abundance Tiller density Tiller size Tiller stem diam

Year Date Year � date Year Date Year � date Date Date

JohnsongrassF 11.28 1.79 1.07 4.76 3.50 6.13 11.73 1.15df 1, 2.0 6, 227.2 6, 227.2 1, 2.2 6, 194.5 4, 194.6 6, 29.4 6, 22.9P 0.078 0.103 0.383 0.148 0.003 �0.001 �0.001 0.365

VaseyÕs grassF 1.59 1.96 1.58 0.60 1.31 0.45 18.93 2.27df 1, 2.0 6, 227 6, 227 1, 2.4 6, 194.2 4, 194.2 6, 22.1 6, 56.7P 0.335 0.073 0.153 0.507 0.255 0.771 �0.001 0.049

RyegrassF 3.25 10.41 2.46 0.02 7.76 0.04 12.32 1.55df 1, 9.9 6, 56.5 6, 56.5 1, 17.4 6, 628.1 4, 628.1 3, 25.6 3, 3.38P 0.102 �0.001 0.035 0.877 �0.001 0.997 �0.001 0.339

BromeF 0.01 8.55 0.47 0.00 6.09 0.01 7.06 4.02df 1, 4.0 6, 65.2 6, 65.2 1, 4.9 6, 195.6 4, 195.6 3, 4.6 3, 6.9P 0.938 �0.001 0.830 0.947 �0.001 1.000 0.035 0.060

CanarygrassF 0.26 4.10 0.15 0.00 1.91 0.00 6.48 0.62df 1, 235 6, 235 6, 235 1, 2.4 6, 195.8 4, 195.8 1, 8.8 1, 1.7P 0.614 0.001 0.990 0.993 0.081 1.000 0.034 0.526

Angleton bluestemF 0.95 2.51 0.51 0.98 1.40 0.53 0.46 2.96df 1, 2.0 6, 60.1 6, 60.1 1, 2.1 6, 55.9 6, 55.9 6, 3.2 6, 3.7P 0.433 0.031 0.798 0.420 0.232 0.716 0.811 0.170

Caucasian bluestemF 0.27 1.51 0.57 0.16 0.80 0.82 0.69 0.38df 1, 7.9 6, 57.4 6, 57.4 1, 8.1 6, 193.6 4, 193.6 3, 2.5 3, 3.0P 0.620 0.191 0.754 0.700 0.573 0.512 0.625 0.774

Hairy crabgrassF 1.28 3.41 0.93 1.70 1.96 1.24 1.80 1.58df 1, 10.0 6, 60.2 6, 60.2 1, 10.1 6, 49.0 4, 49.0 4, 11.2 4, 12.8P 0.284 0.006 0.482 0.221 0.089 0.308 0.199 0.239

Jungle riceF 0.29 1.52 1.90 0.53 1.00 2.23 2.28 4.86df 1, 10.0 6, 60.2 6, 60.2 1, 10.4 6, 47.0 4, 47.0 1, 1 1, 4.5P 0.461 0.187 0.095 0.484 0.484 0.080 0.372 0.085

LongtomF 0.34 1.17 1.37 0.01 0.78 1.46 1.80 0.22df 1, 4.0 6, 227 6, 227 1, 8.3 6, 193.3 4, 193.3 4, 12 4, 9.9P 0.589 0.323 0.228 0.920 0.583 0.215 0.195 0.927

Torpedo grassF 0.77 0.80 1.19 0.88 0.93 1.07 2.22 1.21df 1, 8.0 6, 60.1 6, 60.1 1, 8.0 6, 60.2 4, 60.2 5, 18 5, 5.3P 0.407 0.570 0.323 0.375 0.482 0.393 0.097 0.414

Non-identiÞed perennial grassa

F 0.59 1.78 0.30 0.55 1.20 0.34 9.05 9.86df 1, 2 6, 60.2 6, 60.2 1, 2.1 6, 49.6 4, 49.6 5, 6.5 4, 14P 0.523 0.118 0.936 0.533 0.321 0.852 0.007 0.001

aNo reproductive parts and non-distinctive vegetative material.



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densities in these habitats during the second year ofthe study than during the Þrst year (4.01 � 0.73 versus1.63 � 0.73 immatures per m2). Densities changedwith date (F� 2.52; df � 6, 60.2; P� 0.030), increasingfrom early spring to late fall (Fig. 1A). Across bothyears, the lowest E. loftini densities were observed inApril (1.23 � 0.83 immatures per m2), whereas den-sities were greater in October (3.1-fold) and Decem-ber (3.2-fold). As shown by the nonsigniÞcant year �date interaction (F � 1.42; df � 6, 60.2, P � 0.222),differences inE. loftinidensities as affectedbydatedidnot change between the Þrst and the second year ofthe study. For D. saccharalis, differences in densitiesin noncrop habitats were not detected (F� 1.51; df �1, 2.0; P � 0.344) between the Þrst and second year(0.25 � 0.08 and 0.11 � 0.08 immatures per m2, re-spectively) of the study (Fig. 1B). Although changesin D. saccharalis densities were not detected amongdates (F� 1.67; df � 6, 66.2; P� 0.143), densities werehigh in October 2007 (0.94 � 0.19 immatures per m2,Fig. 1B) but not in October 2008, as evidenced by theyear � date interaction (F � 2.39; df � 6, 66.2; P �0.038).Graminoid Composition in Noncrop Habitats. The

12 most prevalent graminoids surrounding rice Þeldsin Texas are listed in Table 1. The multivariate analysisshows that the relative abundance of at least one ofthese graminoids changed with date (WilksÕLambda � 0.0618; F� 2.02, df � 72, 218.0; P� 0.001),but changes occurred to a different extent betweenthe Þrst and second year of the study (WilksÕLambda � 0.2189; F � 1.53; df � 48, 152.3; P � 0.027for the year � date interaction). In addition, multi-variate analysis comparing tiller density showed that

differences across dates occurred (WilksÕ Lambda �0.0269; F� 2.86; df � 72, 218.0; P� 0.001) for at leastone of the 12 graminoids. The year � date interactionwas not signiÞcant (WilksÕ Lambda � 0.2921; F� 1.19;df � 48, 152.3;P� 0.210). For both relative abundanceand tiller density, the multivariate effect of year couldnot be tested because of an insufÞcient number oferror degrees of freedom.

Johnsongrass was the most often encountered andabundant graminoid (Fig. 2). However, johnsongrassrelative abundance did not differ across dates despitetrends (P � 0.1, Table 1) for a minimum in April(50.4 � 7.0% across both years). Trends (P� 0.1, Table1) for a greater relative abundance were also observedduring the second year of the study (70.8 � 6.2 versus51.9 � 6.2%). Tiller density (Fig. 2B) was affected bydate (Table 1), with a maximum observed in August(44.8 � 3.9 tillers per m2). Johnsongrass size changedwith date (Table 1) with the tallest tillers observed inOctober, and the shortest in February and April (Fig.3A). In addition, johnsongrass stem diameter in-creased from the spring to the winter (Table 1; Fig.3B). During the early spring, dead leaßess tillers re-maining from the previous year as well as young greenvegetative growth with an occasional emerging ßowerwere recorded (Fig. 4A). Flowering peaked betweenApril and late June, and a mixture of vegetative, ßow-ering, and mature tillers occurred between May andAugust (Fig. 4A). Mature johnsongrass showed agingfoliage and empty seed heads, but also green offshootsgrowing from nodal buds. During the fall, a majorityof mature and senescing tillers were present; but veg-etative and ßowering johnsongrass was observed inareas mowed in the spring or summer. During thewinter, a majority of tillers were dead or senescing. Inaddition, young vegetative tillers had emerged in Feb-ruary with 0Ð14 tillers per m2 for an average of 1.8tillers per m2 (Fig. 4A).

VaseyÕs grasswas the secondmostprevalentgramin-oid adjacent to rice Þelds (Fig. 2). Although VaseyÕsgrass relative abundance was not different amongdates (Table 1), trends (P � 0.1) for a lower abun-dance in February (15.1 � 6.0% across both years) anda greater abundance in late June (29.1 � 6.0% acrossboth years) were observed. Differences in tiller den-sities between years and among dates were not de-tected (Table 1; Fig. 2B). During the early spring,VaseyÕs grass bunches exhibited dead plant materialfrom earlier growth, green material in a vegetativestage, and a small proportion of ßowering tillers (Fig.4B). Flowering peaked in the spring, and during thesummer, plants showed a mixture of vegetative, ßow-ering, mature, and senescing tillers. The proportion ofsenescing tillers increased in the fall. In the winter,bunches of VaseyÕs grass were composed of dead andgreen vegetative tillers (Fig. 4B). VaseyÕs grass tillerswere the tallest in August, 1.9- and 1.5-fold taller thanin April and December, respectively (Table 1; Fig.3A). Tiller stem diameter (Table 1) was larger in Maythan in October (1.2-fold, Fig. 3B).

Ryegrass (Lolium spp.), brome (Bromus spp.),and canarygrass (Phalaris spp.) are annual grasses

Table 2. Statistical comparisons for E. loftini infestations re-covered from six grasses commonly found in non-crop habitatsadjacent to rice fields, Texas, 2007–2009

PlantPercentage of

recovered E. loftini

Year Date Year � date

JohnsongrassF 9.67 4.99 0.56df 1, 8.4 6, 55.8 6, 55.7P 0.014 �0.001 0.761

VaseyÕs grassF 0.81 5.88 1.03df 1, 2.0 6, 55.2 6, 55.1P 0.464 �0.001 0.418

RyegrassF 5.82 7.07 3.65df 1, 2.2 6, 61.7 6, 61.7P 0.126 �0.001 0.004

BromeF 1.06 5.24 2.12df 1, 4.2 6, 61.4 6, 61.4P 0.360 �0.001 0.064

CanarygrassF 2.62 1.44 1.44df 1, 7.0 6, 52.1 6, 52.1P 0.150 0.218 0.218

Angleton bluestemF 0.13 1.57 1.22df 1, 63.1 6, 63.0 6, 63.0P 0.717 0.171 0.310



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that did not occur in August, October, or December.Relative abundance for ryegrass showed trends (P�0.1, Table 1) for being greater (2.5-fold) during theÞrst year (Fig. 2A). In addition, ryegrass relativeabundance peaked in April (Fig. 2A). As shown bythe year � date interaction (Table 1), changes inrelative abundance between April and May, andbetween May and late June, occurred to a greaterextent in 2007 (2.9-fold and 58.4-fold, respectively)than in 2008 (2.3-fold and 11.5-fold, respectively)(Fig. 2A). Ryegrass tillers occurred at greater den-

sities in the early spring (April) than during the latewinter (February) (Fig. 2B). Ryegrass tiller sizediffered with date (Table 1). Tillers measured � 70cm during the spring (Fig. 3A), and were the small-est in February (2.9-fold smaller than in April).Differences in ryegrass tiller stem diameter (Fig.3B) were not detected (Table 1). Brome and ca-narygrass relative abundances were affected by date(Table 1), peaking in April and May (Fig. 2A).Brome tillers occurred at greater densities in Feb-ruary and April than in May (Fig. 2B). Canarygrass

Fig. 2. (A) Relative abundance and (B) tiller density (LS means) for seven of the most commonly sampled grasses innoncrop habitats adjacent to rice Þelds in Texas, 2007Ð2009. When a grass did not occur, markers were not included on theÞgure.



33

was not collected in February, and differences intiller density from April to late June were not de-tected (Table 1). Similarly to ryegrass, brome tillerswere the shortest in February (Fig. 3A). In addition,brome tillers collected in February showed a trend(P � 0.1, Table 1) for a smaller stem diameter (Fig.3B). Canarygrass tillers collected in April wereshorter (Table 1) than those tillers sampled in May(1.3-fold, Fig. 3A); however, stem diameter did notchange (Table 1; Fig. 3B). Ryegrass, brome, andcanarygrass typically were ßowering or mature in

early April, senescent or dead in May, and dead inlate June (Fig. 4). However, late brome growthappeared in the vegetative stage in May and June. InFebruary, while young vegetative ryegrass andbrome tillers were growing, canarygrass was not(Fig. 4).

Angleton bluestem [Dichanthium aristatum (Poir.)C.E. Hubbard] and Caucasian bluestem [Bothriochloabladhii (Retz.) S.T. Blake] are two perennial grassesthat occurred sporadically on the study farms, butwere sometimes abundant where present. Differences

Fig. 3. (A) Tiller size and (B) stem diameter (LS means � SE) for seven of the most commonly sampled grasses in noncrophabitats adjacent to rice Þelds in Texas, 2008Ð2009.



34

in Angleton bluestem relative abundance were de-tected (Table 1), with relative abundance greater inthe fall and winter than during the spring and summer(Fig. 2A). However, differences in tiller density (Fig.2B), size (Fig. 3A), and stem diameter (Fig. 3B) werenot detected (Table 1). For Caucasian bluestem, dif-ferences in relative abundance (Fig. 2A), tiller density(Fig. 2B), size (Fig. 3A), and stem diameter (Fig. 3B)were not detected (Table 1). Angleton bluestemÕsphenology was similar to that of johnsongrass. Cau-casian bluestem exhibited vegetative growth from the

spring to the fall, senescent tillers with dry foliage inDecember, and both dead tillers and vegetativegrowth in February.

Hairy crabgrass [Digitaria sanguinalis (L.) Scop.]and jungle rice [Echinochloa colona (L.) Link] are twosummer annual grasses that were found in noncrophabitats directly adjacent to rice Þelds during thesummer and the fall. Hairy crabgrass relative abun-dance changed with date (Table 1), peaking betweenAugust and October, with a maximum of 4.7 � 1.1%recorded in October 2007. However, only limited ev-

Fig. 4. Stem borer noncrop host phenology in habitats adjacent to rice Þelds in Texas, 2008Ð2009.



35

idence for differences in tiller density was detected(Table 1), even with a maximum of 4.3 � 1.3 tillers perm2 (October 2007). When hairy crabgrass tillers werepresent, both size (34.2 � 28.1Ð94.3 � 14.2 cm) andstem diameter (2.1 � 0.2Ð2.5 � 0.1 mm) were notdifferent among dates (Table 1). Similarly to hairycrabgrass, jungle rice does not grow in the spring, andplants were not collected in April and May. However,differences among dates in relative abundance andtiller density (with respective maxima of 3.7 � 0.7%and 6.0 � 1.3 tillers per m2 in August 2007 were notdetected (Table 1). When jungle rice tillers werepresent, differences in size (42.5 � 5.6Ð49.5 � 5.5 cm)were not detected, but there were trends (P � 0.1,Table 1) for a larger stem diameter in October com-pared with December (2.3 � 0.2 and 1.6 � 0.2 mm,respectively). Hairy crabgrass and jungle rice werevegetative early in the summer, ßowering in August,and senescing in October. Only decaying tillers wereobserved in December.

A nonidentiÞed perennial grass with no reproduc-tive parts and nondistinctive vegetative material wascollected in wet areas of noncrop habitats surroundingrice Þelds. The relative abundance and tiller densityfor this grass did not differ throughout the seasons(Table 1), with a maximum of 4.0 � 1.8% (August2007) and 9.9 � 2.7 tillers per m2 (June 2007), respec-tively. Tiller size and stem diameter changed with date(Table 1), with size increasing from spring to fall(31.3 � 5.5 cm in April to 79.0 � 7.8 cm in October)and stem diameter being larger in the spring (3.6 � 0.2mm in April) than during the summer and fall (2.3 �0.1 mm in June). In poorly drained areas, torpedo grass(Panicum repensL.) was also collected. Relative abun-dance and tiller density for torpedo grass were notdifferent throughout the seasons (Table 1), with amaximum of 1.5 � 0.6% (February 2009) and 3.6 � 1.2tillers per m2 (December 2008), respectively.Whereas differences in tiller stem diameter (1.5 �0.2Ð1.9 � 0.1 mm) were not detected (Table 1), therewere trends (P� 0.1, Table 1) for shorter tillers in thespring than in the fall (34.0 � 8.2 cm in April versus60.2 � 6.7 cm in October).

Longtom (Paspalum denticulatum Trin.) was col-lected sporadically with relative abundance and til-ler density reaching 2.3 � 0.7% and 1.6 � 0.6 tillersper m2, respectively, in June 2007 (Table 1). Whenlongtom tillers were present, both their size (44.3 �13.1Ð72.9 � 7.6 cm) and stem diameter (2.4 � 0.4Ð2.8 � 0.3 mm) did not differ among dates (Table 1).Other graminoids collected during this study in-clude fall panicgrass (Panicum dichotomiflorumMichx.); longspike beardgrass [Bothriochloa longi-paniculata (Gould) Allred & Gould]; browntop sig-nalgrass [Urochloa fusca (Sw.) B.F. Hansen & Wun-derlin]; bushy bluestem [Andropogon glomeratus(Walter) Britton, Sterns & Poggenb]; Bermudagrass [Cynodon dactylon (L.) Pers.]; dallisgrass(Paspalum dilatatum Poir.); ßatsedge (Cyperaceae:Cyperus spp.); bristlegrass (Setaria spp.); and Neal-leyÕs sprangletop (Leptochloa nealleyi Vasey).

E. loftini Infestations in Noncrop Plants. Multivar-iate analyses showed that for at least one of the sixgraminoids consistently infested with stem borers(Table 2) the percentage of recovered E. loftini dif-fered with date (WilksÕ Lambda � 0.1058; F � 4.12,df � 36, 222.3, P� 0.001). The year � date interactionwas signiÞcant (WilksÕ Lambda � 0.2515; F � 2.28;df � 36, 222.3; P � 0.001). The multivariate effect ofyear could not be tested because of an insufÞcientnumber of error degrees of freedom.

The percentage of E. loftini recovered from john-songrass differed among dates (Fig. 5A, Table 2), in-creasing from April to August (2.2-fold) and decreas-ing during the fall and winter (2.3-fold). In addition,the univariate analysis (Table 2) suggested that thepercentage of E. loftini recovered from johnsongrasswas greater (1.5-fold) during the second year of thestudy than during the Þrst. During the winter,E. loftiniinfesting johnsongrass were observed near nodes orwithin 5 cm of the soil surface, where visibly live planttissue was found inside stems. In addition, dead des-iccatedE. loftini larvae were observed in February andearly April. The percentage of E. loftini recovered perpercent of johnsongrass relative abundance (Fig. 5B)changed with date (F� 4.59; df � 6, 56.3; P� 0.001),following a pattern comparable to that of the percent-age of recovered E. loftini. Throughout the seasons,the percentage of E. loftini recovered from VaseyÕsgrass changed (Table 2), with an increase (3.3-fold)from April to late June, followed by a decrease (2.2-fold) in August and an increase (3.2-fold) during thefall and winter (Fig. 5A). The percentage of recoveredE. loftini per percent of VaseyÕs grass relative abun-dance changed with date (F � 7.70; df � 6, 60; P �0.001), peaking during the winter (Fig. 5B). At thistime of the year, pupae were observed in dry sectionsof the plants while larvae fed within green vegetativetillers close to soil level. Ryegrass and brome harboredE. loftini during the spring in 2007 and 2008 (Fig. 5A),and one E. loftini larva was recovered from brome inFebruary 2008. The percentage of E. loftini recoveredfrom ryegrass in April was greater (6.1-fold) duringthe Þrst year of the study than during the second(Table 2). A comparable trend (P� 0.1, Table 2) wasobserved for E. loftini recovered from brome (4.0-fold). E. loftini infestations in canarygrass were foundonly during the spring 2007 (Fig. 5A), but differencesin percentages of recovered E. loftini were not de-tected among dates (Table 2). Angleton bluestem wasinfested with E. loftini all year (Fig. 5A). However,differences in percentages ofE. loftini recovered fromthis perennial grass were not detected among dates(Table 2).

In total, 617 and 1,515 E. loftini immatures wererecovered during the Þrst and second year of thestudy, respectively. Ninety-six point one and 98.0% ofthese immatures, for the Þrst and second year of thestudy, respectively, infested the six graminoids ad-dressed in the previous paragraph. The remaining E.loftini immatures were recovered from 12 of the lessabundant grasses and sedges (Table 3). E. loftini was



F5

T3

36

not collected from torpedo grass, Bermuda grass, orbristlegrass.D. saccharalis Infestations in Noncrop Plants. In

total, 94 and 42 D. saccharalis immatures were recov-ered during the Þrst and second year of the study,respectively. These immatures were collected almostexclusively from johnsongrass and VaseyÕs grass,which harbored together 94 and 100% of the infesta-tions for the Þrst and second year of the study, re-spectively. The remaining D. saccharalis larvae werecollected from Angleton bluestem (four larvae), jun-gle rice (one larva), and browntop signalgrass (onelarva). Differences in percentages of D. saccharalisrecovered from johnsongrass and percentages of D.saccharalis recovered per percent of johnsongrass rel-ative abundance (Fig. 5) were not detected betweenthe 2 yr of the study (F � 0.77; df � 1, 9.5; P � 0.403and F � 0.26; df � 1, 16; P � 0.618, respectively) andamong dates (F� 1.01; df � 6, 10.3; P� 0.467 and F�1.08; df � 6, 16; P � 0.417, respectively). In VaseyÕsgrass, differences in percentages of recovered D. sac-charalis and percentages of recovered D. saccharalisperpercentplant relativeabundance(Fig. 5)werenotdetected between years (F� 0.93; df � 1, 8.5;P� 0.361and F� 0.48; df � 1, 8.0; P� 0.508, respectively) and

among dates (F� 1.02; df � 6, 11.1; P� 0.459 and F�0.67; df � 6, 6.4; P� 0.681, respectively). In addition,for johnsongrass and VaseyÕs grass, year � date inter-actions were not detected for the percentages of re-coveredD. saccharalis (F� 0.30; df � 3, 10.3; P� 0.825and F� 0.27; df � 3, 11.3; P� 0.843, respectively) andrecovered D. saccharalis per percent plant relativeabundance (F� 0.01; df � 3, 16;P� 0.999 andF� 1.13;df � 3, 6.5; P � 0.404, respectively).Spring Stem Borer Infestations in Rice Fields. In

early April, old rice stubble was present in all sampledfallow Þelds but one, which had been grazed by cattle.When present, rice stubble showed evidence of stemborer injury from the previous year, but did not hostE. loftini immatures. However, oneD. saccharalispupawas recovered in April 2008 [i.e., 0.04 � 0.04 imma-tures per m2 (mean � SE)]. Although dead rice stub-ble was the only rice material available in fallow Þeldsduring the Þrst year of the study (April 2007), youngrice plants grew in April 2008. Young rice tillers, pres-ent at a density of 37.7 � 7.7 tillers per m2, measured18.3 � 1.1 cm (mean � SE) and harbored 0.7 � 0.2 E.loftini immatures per m2 (mean � SE). Among the 17recovered E. loftini immatures, 64, 18, and 18% weresmall, medium, and large larvae, respectively. Weedy

Fig. 5. Relative stem borer infestations (LS means � SE) in grasses growing in noncrop habitats adjacent to rice Þeldsin Texas, 2007Ð2009. (A) Percentage of recovered E. loftini in six grasses. (B) Percentage of recovered E. loftini per percentjohnsongrass and VaseyÕs grass abundance. (C) Percentage of recoveredD. saccharalis in johnsongrass and VaseyÕs grass. (D)Percentage of recovered D. saccharalis per percent johnsongrass and VaseyÕs grass abundance. Markers were not includedon the Þgure when stem borers were not recovered.



37

grasses were also collected in fallow rice Þelds. Ca-narygrass was present at densities of 1.5� 0.5 and 1.0�0.5 tillers per m2 (mean � SE) in April 2007 and 2008,respectively, with one recovered E. loftini larva inApril 2007 (100% of the recovered immatures in fallowrice). Bristlegrass was present at densities of 0.1 � 0.1and 1.9 � 0.9 tillers per m2 (mean � SE) in April 2007and 2008, respectively, with Þve recovered E. loftinilarvae in April 2008 (23% of the recovered immaturesin fallow rice Þelds).

During both years of the study, stem borer injury orinfestations in young rice plants were not observed inearly April and late May. By late June 2007, newlyplanted rice Þelds on each of the three farms of thestudy were at panicle differentiation or boot stages.Stem borer injury, comprised of one bored tiller andone tiller with feeding signs in the leaf sheath [i.e.,0.04 � 0.03 injured tillers per m2 (mean � SE)], wasrecorded in the older rice Þeld (boot stage) in June2007. By late June 2008, young rice Þelds were atpanicle differentiation, 70% boot and 30% heading, or100% heading stages. Stem borer injury and infesta-tions were observed in one Þeld (70% boot and 30%heading), with an average of 1.67 � 0.81 injured tillersper m2 (mean � SE) and a total of threeD. saccharalislarvae recovered from one quadrat [i.e., 0.11 � 0.11immatures per m2 (mean � SE)].Adult Stem Borer Trapping. E. loftini moth trap

catches (Fig. 6) were two-fold greater during thesecond year than during the Þrst year of the study (F�7.68; df � 1, 7.9;P� 0.025). Differences in trap catchesamong dates were also detected (F� 5.60; df � 6, 56.9;P� 0.001), with moth catches across both years lowestduring the winter and greatest in October (Fig. 6).However, there was a trend (P� 0.1) for a year � dateinteraction (F� 1.97; df � 6, 56.9; P� 0.086). For bothyears of the study, trap catches were comparable for

fall and winter trapping. However, the greatest trapcatches during the second year of the study wereassociated with greater catches between April andAugust with a peak in May, which was not observedduring the Þrst year of the study (Fig. 6).D. saccharalistraps did not function during December and Februarysamplings of both years because the eclosion of virginfemales used as lures did not occur. Thus, data on D.saccharalis ßight activity during the winter were notcollected. D. saccharalismoth trap catches were vari-able but showed differences among dates (F � 4.30;df � 4, 38.1; P � 0.006), with an increase (8.4 -fold)from April to October (Fig. 6). Differences in D.saccharalismoth trap catches between the 2 yr of thestudy were not detected (F � 1.80; df � 1, 4.3; P �0.247), and the year � date interaction was not sig-niÞcant (F � 1.26; df � 4, 38.1; P � 0.303).

Discussion

E. loftini Infestations in Noncrop Hosts. As early asin the 1920s (Van Zwaluwenburg 1926), it was rec-ognized that many large-stemmed grasses could hostE. loftini.However, E. loftini noncrop hosts have onlyrecently received consideration for pest management(Beuzelin et al. 2010, Showler et al. 2011). Our studyprovides the Þrst quantiÞcation of seasonal E. loftiniinfestations in plants other than Þeld crops. Underon-farm conditions of Texas Gulf Coast rice agroeco-systems, infestations innoncropgrassesoccurredearlyduring the spring when young rice does not harbor E.loftini. E. loftini infestations in noncrop grasses sub-sequently built up during the rice growing season, andwere as high as 4.8 immatures per m2 in December,suggesting that weedy habitats surrounding rice Þeldsare major overwintering areas. April sampling in fal-low rice Þelds that had not been plowed showed that

Table 3. Eoreuma loftini larval infestations recovered from 12 grasses and sedges found sporadically in non-crop habitats adjacentto rice fields, Texas, 2007–2009

Plant

2007Ð2008 2008Ð2009

No. quadratsinfested

No. E. loftinirecovered

No. quadratsinfested

No. E. loftinirecovered

Caucasian bluestem 1 on 19 Dec. 2007 1 0 01 on 17 Feb. 2008 2

Hairy crabgrass 2 on 15 Aug. 2007 2 1 on 11 Oct. 2008 11 on 19 Dec. 2007 11 on 17 Feb. 2008 1a

Jungle rice 1 on 15 Aug. 2007 2 0 0Longtom 0 0 2 on 13 Dec. 2008 6Non-identiÞed perennial 1 on 12 Oct. 2007 1 0 0

1 on 19 Dec. 2007 2Fall panicgrass 2 on 30 June 2007 2 0 0

1 on 19 Dec. 2007 31 on 17 Feb. 2008 1

Longspike beardgrass 0 0 1 on 24 May 2008 12 on 28 June 2008 5

Browntop signalgrass 2 on 15 Aug. 2007 2 0 0Bushy bluestem 1 on 17 Feb. 2008 1 1 on 13 Dec. 2008 10Dallisgrass 1 on 30 June 2007 1 0 0Flatsedge 0 0 1 on 14 Feb. 2009 1NealleyÕs sprangletop 1 on 15 Aug. 2007 2 0 0

a pupa was collected.



F6

38

overwintering E. loftini larvae are not found in ricestubble. However, grassy weeds and volunteer ricegrowing in fallowed Þelds can serve as host during thespring.

Pheromone trap data showed that, despite reducednumbers during the cold season, E. loftini moths ßyyear-round in or near noncrop habitats. This is con-sistent with adult seasonal patterns reported by Beu-zelin et al. (2010) and with observations of all devel-opmental stages present at any time of the year insugarcane Þelds of the Texas Lower Rio Grande Valley(Van Leerdam et al. 1986, Meagher et al. 1994). Ro-driguez-del-Bosque et al. (1995) also showed that E.loftini adults continuously emerged during the winterand spring in northern Tamaulipas, Mexico. Thus, therelative role of various host plants in E. loftini popu-lation dynamics is a function of plant availability, at-tractiveness, and suitability throughout the year.

Assessment of the seasonal abundance and phe-nology of noncrop graminoids of Texas Gulf Coastrice agroecosystems, as well as associated E. loftiniinfestations, assisted in identifying primary noncrophosts and their potential role in the pestÕs popula-tion dynamics. Johnsongrass, VaseyÕs grass, ryegrass,brome, Angleton bluestem, and hairy crabgrasswere effective E. loftini hosts that allowed larvalfeeding and life cycle completion. Other grasses andsedges might also be suitable hosts. Graminoids ob-served in our study presented a wide range of plantheight and stem diameter. Physical constraints as-sociated with these plant size characteristics likelyaffect host suitability for stem borer larval devel-opment, with host suitability increasing with plantheight and stem diameter (Beuzelin 2011, Showleret al. 2011). However, stem hardness and nutritionalquality are other key factors impacting host plant

suitability (Beuzelin 2011, Showler et al. 2011). Ourstudy suggests that johnsongrass, which is abundantthroughout the year, plays a substantial role in E.loftini population build-up during the rice growingseason. The observed lack of live johnsongrass tissueduring the winter, however, probably decreasedhost suitability and subsequently E. loftini survivalduring this season. In addition to low temperatures,desiccation is a primary abiotic stem borer mortalityfactor during the winter (Rodriguez-del-Bosque etal. 1995). Therefore, we contend that E. loftini lar-vae establishing in johnsongrass during the fall willcomplete their life cycle during the winter despiteincreased mortality. However, it is unlikely thatdead johnsongrass supports the development ofyoung larvae from E. loftini moths emerging duringthe winter. For VaseyÕs grass, the high percentage ofrecovered E. loftini and percentage of recovered E.loftini per percent plant relative abundance in Feb-ruary indicate that this host becomes increasinglyinfested during the winter. VaseyÕs grass is less in-fested than johnsongrass at comparable phenolog-ical stages (Beuzelin et al. 2010, Showler et al. 2011)but maintains numerous green vegetative tillersthroughout the year. Thus, the substantial perennialavailability of live plant tissue suitable for E. loftinidevelopment likely allows VaseyÕs grass to be a pri-mary overwintering host. In areas with relativelyless johnsongrass or VaseyÕs grass (e.g., transitionbetween farm roads and Þeld margins), a more di-verse mixture of graminoids was observed. Ryegrassand brome are E. loftini hosts in the spring, alsoplaying a role in population build-up early duringthe rice growing season, even if only for a shortwindow of time. Our study also indicated that ca-narygrass may play a comparable role in E. loftini

Fig. 6. E. loftini andD. saccharalis adult trap catches (LS means � SE) in noncrop habitats adjacent to rice Þelds in Texas,2008Ð2009. Markers were not included on the Þgure when traps did not function.



39

population dynamics. Other annual and perennialgrasses (i.e., crabgrass, Angleton bluestem) proba-bly play a minimal role in E. loftini population dy-namics although they may have more substantialroles if abundant in localized areas.

The current study is the Þrst to our knowledge toquantitatively describe graminoids in noncrop habi-tats (i.e., Þeld margins, roadsides, ditches) surround-ing rice Þelds in the Texas Upper Gulf Coast area.These habitats were more variable than adjacent riceÞelds because they were not under intensive manage-ment, and plant species composition was not inten-tionally controlled by the producers. However, thethree study farms exhibited comparable noncrop hab-itat compositions, regardless of management (mow-ing, burning, herbicide applications, absence of man-agement) or localized soil and weather variations.Based on our observations, noncrop habitats sampledin our study appear to be representative of thosehabitats encountered throughout rice areas of theTexas Gulf Coast. The generalization of our results toother Gulf Coast agroecosystems, however, will re-quire additional sampling in Texas and Louisiana.D. saccharalis Infestations in Noncrop Hosts.Com-

plementing earlier studies (Jones and Bradley 1924,Bynum et al. 1938, Bessin and Reagan 1990), we pro-vided the Þrst year-round quantiÞcation of D. saccha-ralis infestations in noncrop habitats. D. saccharaliswas found mostly in johnsongrass and VaseyÕs grass,and infestations were low relative to E. loftini infes-tations. Low area-wide D. saccharalis populations inthe study areas might explain the predominance of E.loftini. Diatraea saccharalis might also rely less onnoncrop hosts thanE. loftini.AdultD. saccharalis trap-ping data from our study provide evidence of mothactivity in the vicinity of noncrop sampling areas. Inaddition, D. saccharalis infestations in experimentalrice plots located within 1.25 km of noncrop samplingtransects in Jackson County represented �99% ofstem borer infestations in JulyÐAugust 2007 (Beuzelin2011). In the Louisiana sugarcane agroecosystem, By-num et al. (1938) and Ali et al. (1986) concluded thatjohnsongrass only played a minor role inD. saccharalispopulation build-up and overwintering. These obser-vations suggest that noncrop hosts might contributeless to D. saccharalis populations than to E. loftinipopulations. Nevertheless, oviposition preference andimmature performance studies would assist in quan-tifying the relative role of noncrop hosts inD. saccha-ralis population dynamics.Pest Management Implications. Although weeds in

rice Þelds such as Amazon sprangletop can increasestem borer infestations (Tindall 2004, Beuzelin et al.2010), cultural management typically keeps weedpopulations low (Kendig et al. 2003), which is whyexclusively noncrop habitats surrounding rice Þeldswere the focus of our study. Research in several agro-ecosystems showed that alternate hosts in noncrophabitats could contribute to increased pest popula-tions. Examples of this relationship include increasedconsperse stink bug, Euschistus conspersus Uhler, in-festations in California tomato, Solanum lycopersicum

L., Þelds (Pease and Zalom 2010), and the build-up ofthe pyralidMussidia nigrivenellaRagoon in Benin (Se-tamou et al. 2000). Populations of the tarnished plantbug, Lygus lineolaris (Palisot de Beauvois), andtwospotted spider mite, Tetranychus urticae Koch,feed on weedy hosts before moving into nearby cot-ton,GossypiumhirsutumL., Þelds (Fleischer and Gay-lor 1987, Wilson 1995). Our study showed that non-crop grasses are sources ofE. loftinipopulations. Thus,noncrop habitat management tactics including mow-ing, applications of herbicides or insecticides, or themodiÞcation of weed species composition (Landis etal. 2000) could help improve rice integrated pest man-agement (IPM). However, the value of this approachremains to be demonstrated. Relationships betweennoncrop host abundance, stem borer population lev-els, and associated crop yield losses have not beenquantiÞed. In addition, noncrop habitats can be asource of biodiversity enhancing natural enemy abun-dance (Altieri and Letourneau 1982, Norris and Kogan2005). Although the red imported Þre ant (Solenopsisinvicta Buren), spiders, and predaceous beetles sup-press D. saccharalis injury to weedy Louisiana sugar-cane (Ali and Reagan 1985, Showler and Reagan1991), their interactions with stem borer populationsin noncrop habitats have not been determined. E.loftini noncrop hosts might also represent refuges forparasitic wasps (Meagher et al. 1998) observed duringsampling. Therefore, designing noncrop habitat man-agement tactics for rice IPM will have to integrate theweed contribution to both pest and natural enemypopulations (Landis et al. 2000, Norris and Kogan2005).Concluding Remarks. Assuming that host-speciÞc

sympatric stem borer strains do not occur (Pashleyand Martin 1987, Martel et al. 2003, Vialatte et al.2005), our study showed that noncrop grasses have thepotential to increase E. loftini pest populations. Thus,the manipulation of E. loftini noncrop sources mayhelp decrease infestations in crop Þelds and slow thespread of this invasive species through Louisiana. Fur-ther research needs to be conducted to quantify therelative contribution of E. loftini oviposition prefer-ence, immature performance, movement, and naturalenemy suppression to pest source-sink interactions inthe agroecosystem. Subsequently, the efÞcacy andeconomic beneÞts of noncrop habitat managementtactics, implemented at both Þeld and regional scales,will have to be assessed. Because E. loftini noncrophosts can sustain D. saccharalis populations, manage-ment tactics targeting noncrop habitats could alsodecrease D. saccharalis pest populations. Togetherwith previous research (Reay-Jones et al. 2008, Beu-zelin et al. 2010), our study provides a foundation fora more comprehensive stem borer management strat-egy including crop and noncrop components of theagroecosystem.

Acknowledgments

We thank rice growers Bill Dishman, Jr., John and JayJenkins, and Gary and Michael Skalicky for permitting us use



AQ: 3

40

of their farmland and for technical assistance. We thankLowell Urbatsch (Herbarium of Louisiana State University)and Eric Webster (LSU AgCenter School of Plant, Environ-mental and Soil Sciences) for identifying numerous grasssamples. We thank Mike Hiller (Texas A&M AgriLife Ex-tension), Waseem Akbar, Blake Wilson, Kyle Baker (LSUAgCenter), and Jannie Castillo (Texas A&M AgriLife Re-search and Extension Center at Beaumont) for their tech-nical assistance. We thank Jeff Davis, Mike Stout (LSU Ag-Center), and two anonymous referees for participating in thereview of the manuscript. This work was supported byUSDA-CSREES Crops-At-Risk IPM program grant 2008-51100-04415. This paper is approved for publication by theDirector of the Louisiana Agricultural Experiment Station asmanuscript number 2011Ð234-5623.

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Bynum, E. K., W. E. Halley, and L. J. Charpentier. 1938.Sources of infestation by the sugarcane borer and trashtreatment for the destruction of overwintering borers.Proc. Int. Soc. Sugar Cane Technol. 6: 597Ð611.

Fleischer, S. J., and M. J. Gaylor. 1987. Seasonal abundanceof Lygus lineolaris (Heteroptera: Miridae) and selectedpredators in early season uncultivated hosts: implicationsfor managing movement into cotton. Environ. Entomol.16: 379Ð389.

Holloway, T. E.,W. E. Halley, U. C. Loftin, and C. Heinrich.1928. The sugar-cane borer in the United States. U.S.Department of Agriculture Technical Bulletin 41: 1Ð77.

Hummel, N. A., T. Hardy, T. E. Reagan, D. K. Pollet, C. E.Carlton, M. J. Stout, J. M. Beuzelin,W. Akbar, andW.H.White. 2010. Monitoring and Þrst discovery of the Mex-ican rice borer Eoreuma loftini (Lepidoptera: Crambi-dae) in Louisiana. Fla. Entomol. 93: 123Ð124.

Johnson, K.J.R. 1984. IdentiÞcation of Eoreuma loftini(Dyar) (Lepidoptera: Pyralidae) in Texas, 1980: Fore-runner for other sugarcane boring pest immigrants fromMexico? Bull. Entomol. Soc. Am. 30: 47Ð52.

Johnson, K.J.R., and M. B. Van Leerdam. 1981. Range ex-tension of Acigona loftini into the Lower Rio GrandeValley of Texas. Sugar Y Azucar 76: 34.

Jones, T. H., and W. G. Bradley. 1924. Certain wild grassesin relation to injury to corn by the “borer” (Diatraeasaccharalis Fab.) in Louisiana. J. Econ. Entomol. 17: 393Ð395.

Karban, R. 1997. Neighbourhood affects a plantÕs risk ofherbivory and subsequent success. Ecol. Entomol. 22:433Ð439.

Kendig, A., B. Williams, and C. W. Smith. 2003. Rice weedcontrol, pp. 457Ð472. In C. W. Smith and R. H. Dilday(eds.), Rice: Origin, History, Technology, and Produc-tion. Wiley, Inc. Hoboken, NJ.

Klots, A. B. 1970. North American Crambinae: Notes on thetribe Chiloini and a revision on the genera Eoreuma Elyand Xubida Schaus (Lepidoptera: Pyralidae). J. N.Y. En-tomol. Soc. 78: 100Ð120.

Landis, D. A., S. D.Wratten, and G. M. Gurr. 2000. Habitatmanagement to conserve natural enemies of arthropodpests in agriculture. Annu. Rev. Entomol. 45: 175Ð201.

Legaspi, J. C., R. R. Saldana, andN. Roseff. 1997. Identifyingand managing stalkborers on Texas sugarcane. Texas Ag-ricultural Experiment Station Publication MP-1777, Col-lege Station, TX.

Letourneau,D. K. 1987. The enemies hypothesis: tritrophicinteraction and vegetational diversity in tropical agro-ecosystems. Ecology 68: 1616Ð1622.

Long, W. H., and S. D. Hensley. 1972. Insect pests of sugarcane. Annu. Rev. Entomol. 17: 149Ð176.

Martel, C., A. Rejasse, F. Rousset, M.-T. Bethenod, and D.Bourguet. 2003. Host-plant-associated genetic differen-tiation in Northern French populations of the Europeancorn borer. Heredity 90: 141Ð149.

Meagher, R. L., Jr., J. W. Smith, Jr., H. W. Browning, andR. R. Saldana. 1998. Sugarcane stemborers and theirparasites in southern Texas. Environ. Entomol. 27: 759Ð766.

Meagher, R. L., Jr., J. W. Smith, and K.J.R. Johnson. 1994.Insecticidal management of Eoreuma loftini (Lepidop-tera: Pyralidae) on Texas sugarcane: a critical review. J.Econ. Entomol. 87: 1332Ð1344.

Norris, R. F., and M. Kogan. 2005. Ecology of interactionsbetween weeds and arthropods. Annu. Rev. Entomol. 50:479Ð503.

Osborn, H. T., and G. R. Phillips. 1946. Chilo loftini in Cal-ifornia, Arizona, and Mexico. J. Econ. Entomol. 39: 755Ð759.

Pashley, D. P., and J. A. Martin. 1987. Reproductive incom-patibilitybetweenhost strainsof the fall armyworm(Lep-idoptera: Noctuidae). Ann. Entomol. Soc. Am. 80: 731Ð733.

Pease, C. G., and F. G. Zalom. 2010. Inßuence of non-cropplants on stink bug (Hemiptera: Pentatomidae) and nat-ural enemy abundance in tomatoes. J. Appl. Entomol. 134:626Ð636.

Reay-Jones, F.P.F., L. T. Wilson, T. E. Reagan, B. L. Leg-endre, andM.O.Way. 2008. Predicting economic lossesfrom the continued spread of the Mexican rice borer(Lepidoptera: Crambidae). J. Econ. Entomol. 101: 237Ð250.

Reay-Jones, F.P.F., L. T. Wilson, M. O. Way, T. E. Reagan,and C. E. Carlton. 2007. Movement of the Mexican rice



AQ: 4

41

borer (Lepidoptera: Crambidae) through the Texas ricebelt. J. Econ. Entomol. 100: 54Ð60.

Rodriguez-del-Bosque,L.A., J.W. Smith, Jr., and J.Martinez.1995. Winter mortality and spring emergence of cornstalkborers (Lepidoptera: Pyralidae) in subtropical Mex-ico. J. Econ. Entomol. 88: 628Ð634.

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Setamou, M., F. Schulthess, S. Gounou, H.-M. Poehling, andC. Borgemeister. 2000. Host plants and population dy-namics of the ear borer Mussidia nigrivenella (Lepidop-tera: Pyralidae) in Benin. Environ. Entomol. 29: 516Ð524.

Showler, A. T., and T. E. Reagan. 1991. Effects of sugarcaneborer, weed, and nematode control strategies in Louisi-ana sugarcane. Environ. Entomol. 20: 358Ð370.

Showler, A. T., J. M. Beuzelin, and T. E. Reagan. 2011. Al-ternate crop and weed host plant oviposition preferencesby the Mexican rice borer (Lepidoptera: Crambidae).Crop Prot. 30: 895Ð901.

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Stubbs, W. C., and H. A. Morgan. 1902. Sugarcane borermoth. La. Agric. Exp. Stn. Bull. 70: 885Ð927.

Tindall, K. V. 2004. Investigation of insect-weed interac-tions in the rice agroecosystem. Ph.D. dissertation. Lou-isiana State University, Baton Rouge, LA.

Tindall, K. V., M. J. Stout, and B. J. Williams. 2004. Effectsof the presence of barnyardgrass on rice water weevil(Coleoptera: Curculionidae) and rice stink bug(Hemiptera: Pentatomidae) populations on rice. Envi-ron. Entomol. 33: 720Ð726.

Van Leerdam, M. B., K.J.R. Johnson, and J. W. Smith, Jr.1986. Ovipositional sitesofEoreuma loftini(Lepidoptera:Pyralidae) in sugarcane. Environ. Entomol. 15: 75Ð78.

Van Zwaluwenburg, R. H. 1926. Insect enemies of sugar-cane in western Mexico. J. Econ. Entomol. 19: 664Ð669.

Vialatte, A., C.-A. Dedryver, J.-C. Simon, M. Galman, andM.Plantegenest. 2005. Limited genetic exchanges betweenpopulations of an insect pest living on uncultivated andrelated cultivated host plants. Proc. R. Soc. B. 272: 1075Ð1082.

Wilson, L. J. 1995. Habitats of twospotted spider mites (Ac-ari: Tetranychidae) during winter and spring in a cotton-producing region of Australia. Environ. Entomol. 24: 332Ð340.

Received 17 February 2011; accepted 5 July 2011.



42

HARVEST CUTTING HEIGHT AND RATOON CROP EFFECTS ON STEM BORER INFESTATIONS IN RICE

J. M. Beuzelin1, A. Mészáros1, M. O. Way2, and T. E. Reagan1

1Department of Entomology, LSU AgCenter 2Texas A&M AgriLife Research and Extension Center at Beaumont

A two-year field study near Ganado, TX compared infestations of the Mexican rice borer

(MRB) and sugarcane borer (SCB) in rice as affected by main crop harvest cutting height and the production of a ratoon crop. Substantial infestations (> 0.52 stem borers/ft2) remained in rice culms regardless of main crop cutting height (8 vs. 16 in.). However, the 8-in. cutting height reduced MRB infestations 70 to 81% whereas SCB infestations were not affected (Fig. 1). Plant dissections prior to main crop harvest showed that compared to SCB, relatively more MRB are located above 8 in. from the base of the culm (Fig. 2).

In October, the ratoon crop was more infested with stem borers than the unmanaged main crop stubble during the first year of the study. The opposite was observed during the second year. Differences in unmanaged main crop stubble phenology between the two years likely caused these differences in infestation levels. During the post-growing season, infestations in main and ratoon crop stubble decreased over the winter. After favorable winter conditions, infestations in main and ratoon crop stubble were not different, attaining 0.31 MRB/ft2 and 0.04 SCB/ft2 by March 2008 (Fig. 3). In March 2009, rice stubble harbored 0.03 MRB/ft2 and 0.02 SCB/ft2 regardless of whether only a main crop or a main and ratoon crop had been produced (Fig. 3). This study showed that a lower rice harvest cutting height can suppress late season MRB populations. Furthermore, rice stubble under favorable conditions represents a substantial overwintering habitat, thus warranting evaluation of pest management tactics targeting overwintering populations.

August 2007 August 2008

Fig. 1. Stem borer infestations in rice main crop stubble as affected by harvest cutting height in 2007 and 2008, Ganado, Texas. For a stem borer species in a year, * indicates infestations differed (P < 0.05).

0

1

2

3

4

5

MRB SCB

No.

ste

m b

orer

s / s

q. ft

8 in 16 in

0

0.5

1

1.5

2

MRB SCB

No.

ste

m b

orer

s / s

q. ft

8 in 16 in

*

*

43

Fig. 2. Stem borer infestations by location in rice culms prior to main crop harvest in 2008, Ganado, Texas.

2007-2008 2008-2009

Fig. 3. Late and post-growing season MRB infestations in rice, Ganado, Texas, 2007-2008 and 2008-2009.

0

0.5

1

1.5

2

MRB SCB

No.

ste

m b

orer

s / s

q. ft

Below 8 in

Above 8 in

0.0

0.5

1.0

1.5

2.0

2.5

October January March

No.

MR

B /

sq. f

t

Non-ratoon Ratoon

0

1

2

3

4

5

6

7

October January March

No.

MR

B /

sq. f

t

Non-ratoon Ratoon

44

TRAPPING FOR MEXICAN RICE BORER IN THE TEXAS RICE BELT, 2010

Mo Way1, Becky Pearson1, Gene Reagan2, Julien Beuzelin2 1Texas A&M AgriLife Research, 2LSU AgCenter

Mexican rice borer (MRB) pheromone traps were set up in selected counties of the Texas

Rice Belt (TRB). Although MRB was detected for the first time in Louisiana in November 2008, it was collected for the first time in Orange Co. in September 2010 (Table 1). Data are being used to follow the progress of MRB population densities over time in the TRB. Eventually, the data may be used to predict MRB outbreaks. Trap operators for this study include Becky Pearson (Chambers and Jefferson Cos.), Jack Vawter (Colorado Co.), Ron Holcomb (Liberty Co.), Mike Hiller (Jackson Co.), Kelby Boldt (Jefferson Co. – sugarcane), and Noelle Jordan (Orange Co.). Table 1. Monthly totals of Mexican rice borer adults from pheromone traps (2 traps/county) located next to rice, sugarcane or fallow fields on the Texas Upper Gulf Coast in 2010

Month Chambers Co. Colorado Co. Jackson Co. Jefferson Co. Liberty Co. Orange Co.

rice rice rice rice sugarcanea rice fallow

January 0 0 0 0 NA NA NA February 0 2 5 0 NA 2 NA March 15 60 27 18 NA 21 NA April 703 2259 41 160 NA 46 0 May 216 154 71 31 NA 78 0 June 379 181 336 109 87 343 0 July 116 112 81 88 96 74 0 August 347 144 93 118 150 70 0 September 248 267 308 49a 82 272 2 October 997 380 700 26a NA 707 3 November 303 104 449 19a NA 441 1 December 206 59 919 10a NA 784 NA

a Monthly total for one trap

45

RICE INSECTICIDE EVALUATION STUDIES

Mo Way, Mark Nunez, Becky Pearson Texas A&M AgriLife Research and Extension Center at Beaumont

Six studies assessing the efficacy of insecticides for rice water weevil (RWW),

Lissorhoptrus oryzophilus Kuschel, and stalk borer management were conducted in 2011 at the Ganado Research Station and the Texas A&M AgriLife Research and Extension center at Beaumont. A study conducted in 2009 is also reported. 1. Cocodrie Seed Treatments, Ganado, TX, 2011

Low populations of RWW were recorded, but these data show Dermacor X-100 significantly reduced whitehead numbers. Table 1. Mean data for Cocodrie seed treatments. Ganado, TX. 2011

Treatment Rate (fl oz/cwt)

Paniclesa/ft of row

RWWb/5 cores WHsb/4 rows

Yield (lb/A) Jun 7 Jun 17

Untreated --- 29 9 a 5 31 a 7903 CruiserMaxx Rice 7.0 27 4 b 8 23 a 8427

Nipsit Inside 1.92 28 3 b 4 20 a 8261 Dermacor X-100 1.75 fl oz/A 31 1 c 3 5 b 8673

NS NS NS a Panicles counted on Jul 12 b RWW = rice water weevil; WH = whitehead Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA, LSD) 2. XP753 Seed Treatments, Ganado, TX, 2011

Low populations of RWW were recorded, but Dermacor X-100 significantly reduced whitehead numbers. Hybrids generally produce fewer whiteheads than inbreds, but hybrids are still susceptible (Compare Tables 1 and 2). Table 2. Mean data for XP753 seed treatment. Ganado, TX. 2011

Treatment Rate (fl oz/cwt)

Paniclesa/ft of row

RWWb/5 cores WHsb/4 rows

Yield (lb/A) Jun 7 Jun 17

Untreated --- 25 6 3 12 a 9303 b CruiserMaxx Rice 7.0 28 6 3 13 a 9303 b

Nipsit Inside 1.92 21 6 5 15 a 9551 ab Dermacor X-100 1.75 fl oz/A 26 1 2 2 b 10099 a

NS NS NS a Panicles counted on Jul 12 b RWW = rice water weevil; WH = whiteheads Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA, LSD)

46

3. Dermacor X-100 Ratoon Study, Ganado, TX, 2011 Low populations of RWW were recorded, but Dermacor X-100 significantly reduced

whitehead numbers. The observed yield response was primarily due to stalk borer control. Table 3. Mean data for Dermacor X-100 ratoon study. Ganado, TX. 2011

Treatment Rate (lb ai/A)

Timinga Panicles/ft

of row RWWb/5 cores WHsb/

4 rows Yield (lb/A) RWW SB Jun 7 Jun 17

Untreated --- --- --- 28 12 ab 12 a 34 a 7270 b Karate Z 0.03 BF --- 30 4 bc 3 b 35 a 7247 b Karate Z 0.03 --- LB/H 28 18 a 10 a 23 a 7939 a

Dermacor X-100 1.75 fl oz/A ST ST 29 2 c 0 b 3 b 8244 a NS

a RWW = treated for rice water weevil before permanent flood (BF); LB/H = late boot/heading; ST = seed treatment b RWW = rice water weevil; WH = whitehead Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD) 4. Seed Treatment Replant Study, Beaumont, TX, 2011

These data show Dermacor X-100 provided good control of RWW and stalk borers when untreated rice seed was replanted after treated rice seed. Table 4. Mean data for second planting of seed treatment replant study. Beaumont, TX. 2011

Description Rate (fl oz/cwt)

Timing Stand (plants/ft of row)

RWWa/5 cores WHsa/4 rows

Yield (lb/A) 1st

planting 2nd

planting Jul 19 Jul 29 Untreated --- --- --- 11 48 a 26 a 23 a 7783 d

CruiserMaxx Rice 7 Tb Ub 10 8 bcd 9 b 16 ab 8374 bc CruiserMaxx Rice 7 T T 12 3 d 8 b 17 ab 8089 cd Dermacor X-100 1.75 fl oz/A T U 11 15 b 8 b 0 c 8445 abc Dermacor X-100 1.75 fl oz/A T T 11 3 cd 3 c 1 c 8944 a NipsIt INSIDE 1.92 T U 10 9 bc 7 bc 14 ab 8278 bcd NipsIt INSIDE 1.92 T T 11 5 cd 8 bc 12 b 8645 ab

NS a RWW = rice water weevil; WH = whitehead; T = treated; U = untreated b T = treated; U = untreated Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD)

47

5. Dermacor X-100 Large Plot Study – Cocodrie, Beaumont, TX, 2011 This non-replicated study with Cocodrie shows Dermacor X-100 reduced whitehead numbers (stalk borer injury) 80%. Stalk borers were a combination of MRB and SCB. Table 5. Mean insect data for Dermacor X-100 large plot study (Cocodrie). Beaumont, TX. 2011

Treatment Rate RWWa

feeding scars/30 plants

Plants with

insect damageb

RWW/5 cores WHsa/4 rows

Yield (lb/A)

fl oz/cwt lb ai/A Jun 3 Jun 13 NipsIt INSIDE 1.92 0.06 5 11 8 8 56 7601

Dermacor X-100 1.75 fl oz/A 0.071 34 14 8 6 17 7514 CruiserMaxx Rice 7 0.112c 8 13 18 2 102 7661

Karate Zd --- 0.03 41 15 17 16 121 7110 Untreated --- --- 29 9 74 66 87 7361

a RWW = rice water weevil; WH = whitehead b From 20 inspected plants (primarily thrips injury, difficult to separate from non-insect injury) c 0.112 lb ai/A of insecticide d Foliar treatment applied before permanent flood 6. Dermacor X-100 Large Plot Study – XP753, Beaumont, TX, 2011 This non-replicated study with XP753 (hybrid) suggests hybrids do not produce as many whiteheadss as inbreds (compare Tables 5 and 6). However, significant yield losses, probably due to incomplete grain fill, are still observed in hybrids. Table 6. Mean insect data for Dermacor X-100 large plot study (XP753). Beaumont, TX. 2011

Treatment Rate RWWa

feeding scars/30 plants

Plants with

insect damageb

RWW/5 cores WHsa/4 rows

Yield (lb/A)

fl oz/cwt lb ai/A Jun 6 Jun 16 NipsIt INSIDE 1.92 0.019 14 8 0.8 5.8 5 9340

Dermacor X-100 1.75 fl oz/A 0.071 18 7 1.3 7.8 1 9495 CruiserMaxx Rice 7 0.035c 4 6 1.0 8.3 8 8952

Karate Zd --- 0.03 30 8 5.8 8.0 5 8986 Untreated --- --- 26 9 8.8 23.3 8 9123

a RWW = rice water weevil; WH = whitehead b From 20 inspected plants c 0.035 lb ai/A of insecticide d Foliar treatment applied before permanent flood

48

7. Dermacor X-100 Ratoon Study, Ganado, TX, 2009 These data show control of stalk borers on the main crop can have a positive yield effect on the ratoon crop. Table 7. Mean data for stem borer control in main and ratoon crop rice. Ganado, TX. 2009

Treatment Rate lb ai/A

Timinga WHsb/4 rows Yield (lb/A) Main Ratoon Main Ratoon Main Ratoon Total

Cocodrie:

Dermacor X-100 0.025mg ai/seed ST U 1 b 14 c 7482 a 4516 ab 11998 ab

Karate Z 0.03 T T 1 b 2 d 7769 a 4867 a 12635 a Karate Z 0.03 T U 3 b 35 b 7642 a 4282 b 11923 ab Karate Z 0.03 U T 10 a 2 d 6747 b 4612 ab 11358 b Untreated --- U U 8 a 51 a 6931 b 3433 c 10363 c XL723:

Dermacor X-100 0.05 mg ai/seed ST U 0 1 b 9326 ab 5291 14617

Karate Z 0.03 T T 0 1 b 9704 a 4953 14657 Karate Z 0.03 T U 0 6 a 9585 a 4361 13945 Karate Z 0.03 U T 0 1 b 8940 b 4793 13734 Untreated --- U U 0 7 a 8942 b 4346 13289 NS NS NS a ST = seed treatment; T = treated with Karate Z @ 1 – 2” panicle and late boot/early heading; U = untreated b WHs = whiteheads Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD)

49

Beaumont Sugarcane Variety Test Plot Plan 2010

US 02-9010 (3 rows) HoCP 91-552 (2 rows) US 07-9027 (2 rows)

V

US

04-9

076

US 08-9003 Ho 06-563 HoCP 05-961 L07-57 HoCP 05-902

US

07-9

019 HoCP 85-845 Ho 07-604 Ho 07-612 US 08-9001 Ho 06-537

HoCP 04-838 L 03-371 Ho 06-9610 N-24 N-27

L 01-299 Ho 07-613 HoCP 00-950 HoCP 96-540 N-17

N-21 US 01-40 L 07-68 Ho 07-617 US 93-15

IV

US

07-9

612

HoCP 05-902 Ho 07-612 US 01-40 HoCP 05-961 Ho 07-604

HoC

P 04

-838

US 93-15 Ho 07-613 L 01-299 US 08-9003 US 08-9001

L 07-57 L 07-68 HoCP 85-845 Ho 06-563 N-24

HoCP 00-950 L 03-371 HoCP 04-838 N-21 Ho 07-617

N-17 HoCP 96-540 N-27 Ho 06-537 Ho 06-9610

III

US

07-9

015

Ho 06-563 Ho 07-612 HoCP 05-961 US 08-9003 L 07-57

US

02-1

13 Ho 06-9610 HoCP 00-950 N-21 HoCP 04-838 HoCP 96-540

Ho 07-617 N-24 N-17 US 93-15 N-27

HoCP 85-845 Ho 07-613 L 03-371 HoCP 05-902 US 01-40

US 08-9001 L 01-299 Ho 07-604 L 07-68 Ho 06-537

II

US

07-9

014

Ho 07-617 HoCP 04-838 HoCP 85-845 N-27 L 03-371

US

07-9

017 N-17 Ho 07-613 N-21 Ho 06-9610 HoCP 00-950

L 01-299 US 93-15 US 01-40 HoCP 96-540 N-24

Ho 06-563 Ho 06-537 Ho 07-612 US 08-9001 L 07-68

Ho 07-604 HoCP 05-961 US 08-9003 L 07-57 HoCP 05-902

I

CP

44-1

55

HoCP 05-902 US 01-40 Ho 07-612 Ho 06-537 L 03-371 L

01-2

99 L 07-57 L 07-68 HoCP 00-950 HoCP 85-845 US 08-9003

Ho 06-563 HoCP 04-838 N-17 HoCP 05-961 US 08-9001

L 01-299 N-21 N-27 HoCP 96-540 Ho 07-604

Ho 06-9610 N-24 US 93-15 Ho 07-617 Ho 07-613

HoCP 85-845 (7 rows) ↓ Plot size = 1 row, 5.25 ft row width, 12 ft long with 4 ft alley N Shaded plots = Seed increase as buffer

50

Sugarcane Host Plant Resistance Test Insect Nursery

Beaumont, TX

2011

PLOT PLAN

US

02

-9010

US 02-9010

V

HoCP 08-726 Ho 08-706 L 08-090 L 08-088

Ho 08-711 Ho 08-717 HoL 08-723 L 08-075

L 08-092 L 79-1002 Ho 08-709 HoCP 85-845

HoCP 91-552 Ho 02-113 HoCP 00-950 Ho 05-961

L 07-57 HoCP 04-838 Ho 07-613 blank

IV

L 08-092 L 08-090 blank L 08-088

Ho 08-709 Ho 08-717 HoL 08-723 L 08-075

HoCP 85-845 HoCP 08-726 Ho 08-711 Ho 08-706

Ho 05-961 HoCP 91-552 Ho 02-113 HoCP 00-950

HoCP 04-838 L 79-1002 L 07-57 Ho 07-613

III

HoCP 00-950 L 08-088 L 08-075 Ho 08-717

HoL 08-723 L 08-090 Ho 08-706 Ho 08-711

Ho 08-709 HoCP 04-838 HoCP 85-845 blank

HoCP 08-726 HoCP 91-552 L 79-1002 Ho 02-113

Ho 07-613 L 07-57 Ho 05-961 L 08-092

II

L 08-075 L 08-092 L 08-090 L 79-1002

HoL 08-723 Ho 08-709 Ho 08-717 L 08-088

blank Ho 08-706 HoCP 08-726 Ho 08-711

Ho 02-113 HoCP 85-845 HoCP 00-950 HoCP 91-552

Ho 05-961 L 07-57 Ho 07-613 HoCP 04-838

I

L 08-092 L 08-090 blank Ho 05-961

L 07-57 Ho 07-613 Ho 08-709 L 08-075

Ho 08-717 L 08-088 L 79-1002 HoCP 04-838

Ho 08-706 HoL 08-723 HoCP 08-726 HoCP 00-950

Ho 08-711 Ho 02-113 HoCP 85-845 HoCP 91-552

US 02-9010

Plot size = 1 row, 5.25 ft row width, 12 ft long with 4 ft alley

N Buffer rows on north (6 ft), south (6 ft) and east (1 row) ends of test

51

Example data sheet: Mexican rice borer sugarcane infestation, 2002-2011

Stalk number Larvae position on plant (sheath, node, internode)

Internode position Feeding signs (sheath and leaf)

Larvae instar Bored internodes

Field Ganado Date: Treatment:StalkP Species S N I S N I S N I S N I S N I S N I S L Bored1234567891011121314151617181920

Total joints

In each square, number of live larvae found

Borer species (Mexican rice borer or sugarcane borer)

52

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beaumont site visit: mexican rice borer and sugarcane ...€¦ · beaumont site visit: mexican rice...

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