What We’re Learning About Neonicotinoid Insecticides, and New

Insects and Insecticides for 2014Rick Foster and Kira NixonDepartment of Entomology

Purdue University

Neonicotinoids

• Bind to the nicotinic acetylcholine receptors in the central nervous system

• Similar mode of action to nicotine without the mammalian toxicity

• Effective against sucking and chewing insects• Highly systemic

SafetyInsecticide Oral LD50 Dermal LD50

Admire* > 5000 > 5000

Platinum* > 2000 > 5000

Assail* 330 571

Imidan 147 ‐ 316 > 4640

Lannate 30 ‐ 34 > 2000

Capture > 5000 > 2000

LD50 = lethal dose for 50% of the population; Expressed in milligrams/kilogram

* = Neonicotinoid

Neonicotinoid Profile

• Low oral and dermal human toxicity• Most considered “unlikely” carcinogens• Little or no eye irritation• Little or no skin irritation• Limited effects on wildlife or arthropod predators or parasites

• Some environmental persistence, especially in the soil

• Actively systemic within the plant (or animal)

Neonicotinoids and Bees

• Most of the neonicotinoids are highly toxic to bees– LD50 = 22‐44 nanograms per bee– 1 nanogram is 1 billionth of a gram

• Systemic activity of neonicotinoids moves the insecticide to the flowers where bees tend to feed

Background:Neonicotinoids and Agronomic crops

• Most agronomic crops are treated: all corn (95+ million acres), 60-70% soybeans (40+ million acres), canola, wheat, cotton. Total of ≈ 200 million acres/year

• Systemic in plant tissues to protect seed, seedling and root systems. Effectiveness varies widely across pests.

Corn planting background• Modern planters use a vacuum system to move/plant

seeds

• Treated seeds are sticky – require talc in planter to ensure uniform planting

• Used talc is exhausted with air during and after planting

Planter cleaning demonstration

Results:Planter exhaust (used talc)

• Extremely high concentrations of seed coatings found in used talc

Seedtype Thiamethoxam Clothianidin Metalaxyl Trifloxystrobin

Unusedtalc ND ND ND ND

Treatedseed1 735,000ppb

3,400,000ppb

116,000ppb

66,000ppb

Treatedseed2 68,000ppb

10,000,000ppb 92,000ppb

50,000ppb

Treatedseed3 13,240,000ppb 4,900,000ppb

263,000ppb

503,000ppb

Treatedseed4 70,000ppb

15,030,000*ppb

131,000ppb

313,000ppb

Untreatedcornseed

ND 47,000ppb ND ND

* = equivalent to approx. 700,000X the contact LD50 (20 ng)

Results

• Seed industry is moving rapidly toward reducing or eliminating the use of talc in planting operations

• Chemical industry is sponsoring major research projects at universities to look for ways to reduce impacts on bees

• Other research is continuing

What About Vegetables?

• Galen Dively (U. Maryland) looked at various application methods on pumpkins– Imidacloprid– Dinotefuran– Thiamethoxam

Neonicotinoid Residues in Pumpkin Pollen and Nectar

(ng/g)

Insecticide Application Method Pollen Nectar

Imidacloprid Bedding drench 4.9 c 0.4 c

Transplant water (low) 36.7 b 5.7 b

Transplant water (high) 60.9 ab 7.4 ab

Transplant water/drip 80.2 a 11.2 a

Dinotefuran Transplant water/drip 57.5 ab 9.2 a

Two foliar sprays 88.3 a 7.5 a

Thiamethoxam Transplant water/drip 68.0 a 9.5 a

Two foliar sprays 95.2 a 8.2 a

Conclusions

• Highest residues were found in samples receiving the high rate in split applications

• The closer the application to planting, the lower the residues

• Applications made close to flowering have the potential for a significant affect on bees

Our Studies ‐ 2012

• Study was begun before Dively’s work was published

• Original intent was to look at effectiveness of FarMore technology (thiamethoxam seed treatment) compared with other insecticides, including neonicotinoids on pumpkins

• Collected pollen from flowers and analyzed them for presence of neonicotinoidinsecticides

Thiamethoxam Residues in Pumpkin Pollen

Treatment: Seed/Soil/Spray PPB Thiamethoxam

Untreated 0.00

Untreated Seed + Platinum 18.13

Untreated Seed + Actara 4.43

FarMore Seed 2.24

FarMore Seed + Platinum 12.97

FarMore Seed + Actara 4.96

Platinum applied in transplant water at planting.Actara applied as a foliar spray prior to flowering.

2013 STUDIES

Neonicotinoids and Indiana Melons

– Control of striped cucumber beetle, aphids, leafhoppers etc.

– Safer, more selective and effective than some alternatives

– Imidacloprid, thiamethoxam, acetamiprid

Problem

• Most neonicotinoids are highly toxic to honey bees– Lethal effects– Sublethal effects 

• Altered behavior, decreased learning ability and memory, lack of coordination, inability to return home

Project Objectives:Determine the risks posed to honey bees by neonicotinoid insecticides applied to cantaloupe using different delivery methods.

1. Determine residue concentrations of several recommended neonicotinoids in cantaloupe pollen.

2. Couple field residue concentrations with known honey bee toxicological sensitivity.

Ultimate Goal:Modify our neonicotinoid product and application 

method recommendations to growers to maximize insecticide efficacy while minimizing honey bee health risks. 

Materials and Methods• Meigs Farm

– Throckmorton Purdue Agricultural Center, Lafayette, IN

• Cantaloupe – variety ‘Athena’• Growing Conditions:

• Plant April 17th in soilless potting mix in 72‐count plastic bedding trays

• Transplant into field May 13th

• Black plastic mulch• Drip irrigation

Field DesignTreatment Chemical Trade Name Application Method

1 Control2 Imidacloprid Admire Pro Soil ‐ bedding tray, transplanting3 Thiamethoxam Platinum Soil ‐ transplanting4 Imidacloprid Admire Pro Soil ‐ transplanting5 Thiamethoxam Actara Foliar Spray – June 246 Acetamiprid Assail Foliar Spray – June 247 Thiamethoxam FarMore Seed treatment

Untreated Plants

Sample Collection

• Flowers collected from 6am‐9am, June 27th– 1 gallon ziplock bags– stored at 5 ̊C for 2 days

0

20

40

60

80

100

120

Average Imidacloprid Concentration (ppb) 

Control Admire ProBedding/Transplant

Admire ProTransplant

1.8 +/‐ 0.21 87 +/‐ 18 96 +/‐ 20

12‐48 ppb decrease olfactory learning & memory, reflex response, distance moved and increased mortality

0

10

20

30

40

50

60

70

80

90

Average Thiamethoxam Concentration (ppb) 

67 ppbUnable to fly home

0.29 +/‐ 0.06

Control Platinum Actara FarMore

64 +/‐ 17 76 +/‐ 9 0.67 +/‐ 0.34

0

20

40

60

80

100

120

140

160

180

200

Average Acetamiprid Concentration (ppb)

Control Assail

0.345 +/‐ 0.16 151 +/‐ 31

No sublethal effects until 1000 ppb

Conclusions

• Foliar sprays of Assail should have no negative impacts on honey bees

• FarMore seed treatments should have no negative impacts on honey bees

• The use of Platinum or Admire Pro may have adverse effects on honey bees

• The use of Actara as a foliar spray may have adverse effects on honey bees

Questions Still to Be Answered

• Will these results be similar in a second year?• Will lower rates of Admire Pro, Platinum, or Actara result in lower residues but still provide acceptable levels of control?

• How long will FarMore treated seeds provide control of striped cucumber beetles and protection from bacterial wilt?

What’s New for 2014

• Closer insecticide was added to the recommendations for control of aphids, whiteflies, and plant bugs on several crop groups

• Blackhawk insecticide was added to the recommendations for control of caterpillars and Colorado potato beetles on several crop groups.

• The threat from the invasive brown marmoratedstink bug was specifically addressed for several crop groups.

Brown Marmorated Stink Bugs Found in Indiana

• First discovery in Elkhart County in October, 2010

• Confirmed in 14 counties• Likely present in many other locations

Brown Marmorated Stinkbug, Halyomorpha halys (Stal)

Why should we care about brown marmorated stink bugs?

• Serious pest of vegetables such as tomatoes, peppers, sweet corn, green beans, etc.

• Serious pest of fruit crops such as peaches, apples, grapes, etc.

• Pest of corn and soybeans• Pest of many ornamental plants• They like to overwinter inside homes• They are difficult to control• They stink

BMSB

• They will likely first be a problem as an invader of homes – lots of interest right now

• I suspect that it is present in almost every county in Indiana

• I expect that 2014 will be the first year where we see serious crop injury

Questions?