biological control of hydrilla - uf/ifas oci · “ideal” hydrilla biocontrol agent • narrow...
TRANSCRIPT
Biological Control of Hydrilla
J.P. Cuda1, W.A. Overholt2, K.T. Gioeli3
and S.A. Hetrick4
1Entomology & Nematology Dept., Gainesville, FL 326112BioControl Research & Containment Lab., Ft. Pierce, FL 34945
3Osceola County Extension, Kissimmee, FL 347444St. Lucie County Extension, Ft. Pierce, FL 34945
Acknowledgements• Karen Brown• Mike Grodowitz• Mike Netherland• Tobias Schmid• Judy Shearer• Karen Stratman
• USDA NIFA Grant
What is Biological Control ?• Intentional Use of Natural Enemies
to Weaken and Suppress Invading Plants– Increase Leaf Mortality, Inhibit Growth,
Reduce Flower & Seed Production
• Three Categories:– Augmentation (Arthropods, Pathogens, Fish)
– Importation or Classical (Arthropods, Pathogens)
– Fortuitous (Arthropods, Pathogens)
TACTICS OF AQUATIC PLANT MANAGEMENT
BIOLOGICAL CHEMICAL PHYSICALPREVENTION
IMPORTATION ADVENTIVE AUGMENTATION INORGANICORGANIC
NATURAL SYNTHESIZED NATURAL SYNTHESIZED
PERMANENT TEMPORARY
Relative Degree of Sustainability
CLASSICAL INUNDATIVEFORTUITOUS
Importation (Classical) BioControl
• Introduction and Release of Host Specific Natural Enemies from the Weed’s Native Range to Reduce Its Growth, Reproduction or Density in the Adventive1
Range
1Arrived into a specified geographical region from elsewhere by ANY means.
Worldwide Distribution of Hydrilla
http://www.discoverlife.org/mp/20m?kind=Hydrilla+verticillata&guide=Aquatic_Invasives
cpDNA haplotypes
China F
China G
China H
Japan
Indonesia
Taiwan
12
19
1 China E6
5
3
4
2
7
1019
China A
China C
Korea,NE U.S.A
Australia,New Zealand
11
1
11
1
China B,India
China J China IPoland
China D
Florida, Texas, California, Louisiana,
Africa, India, Panama, Pakistan
22
11
Hydrilla Genetic Studies
Williams et al., unpubl.
Quarantine Facilities
USDA-ARS Laboratory, Ft. Lauderdale
UF/DACS Laboratory, Ft. Pierce
FL BioControl Lab, Gainesville
UF Entomology Dept, Gainesville
Goal of Classical BioControl
• Reunite the Natural Enemies with Their Host Plants to Suppress and Maintain the Density of the Weeds at “ACCEPTABLE” Levels
• Biological Control is NOT Eradication
How Does BioControl Work ?
TIME
NU
MB
ER
EIL
EDNatural Enemy
Weed
ED
• Weed establishes equilibrium density (ED)*above ecological or economic injury level (EIL)**
• Natural enemy lowers ED & maintains it below EIL
*ED - Long term mean density**EIL – Lowest density causing
economic or ecological damage
Advantages of Classical Weed BC
• Minimal Impact on Non-targets• Environmentally Friendly• Classical Biocontrol is Permanent• Suitable for Weeds of Natural
Areas and Aquatic Ecosystems• Relatively Inexpensive
Costs/Benefits of BioControl
(after Mentz 1987)
Release of Bioagent
Time
Benefits (+$)
Costs (-$)
Research & Development
Maintenance & Monitoring
Disadvantages of Classical BC
• Control is Not Immediate (5–10 years)
• Little Interest in Commercialization• Unpredictable
– Some Natural Enemies Fail to Establish– Some Natural Enemies are Ineffective
• Abiotic and Biotic Interference
Classical Hydrilla BioControl Agents
Hydrilla Leaf Miners, Hydrellia spp.
Factors Impacting Hydrellia
y = -53.114x + 2300.4R2 = 0.5772
0
400
800
1200
1600
2000
20 25 30 35 40 45
MAXIMUM TEMPERATURE (oC)
DE
NS
ITY
• Hydrilla Mat Surface Temperature
Factors Impacting Hydrellia• Predation by Damselfly & Dragonfly Naiads
0
200
400
600
800
1000
1200
1400
1600
1800
6-Ju
l-95
4-Aug-
95
13-S
ep-9
5
12-O
ct-95
9-Nov
-95
13-D
ec-95
29-Ja
n-96
28-F
eb-9
6
27-M
ar-9
6
29-A
pr-9
6
29-M
ay-9
6
25-Ju
n-96
24-Ju
l-96
27-A
ug-9
6
25-S
ep-9
6
22-O
ct-96
25-N
ov-96
28-Ja
n-97
0
50
100
150
200
250
300
HP LARVAE
DRAGONFLY NAIADS
UK
HY
DR
EL
LIA
DE
NS
ITY
(n
o. /
m2 )
DR
AG
ON
FLY
DE
NS
ITY
(no
. / m2)
Factors Impacting Hydrellia
• Parasitism– Significant– Upwards of 30%
• Late in growing season
– Pupal parasitoid behavior
• Selects wide range• Stage chosen =
most successful
TRICHOPRIA WASP
Augmentative BioControl
• Release of Large Numbers of a Biological Control Agent to Achieve a Rapid Effect
• There is No Expectation the Biological Control Agent will Establish a Permanent (= Reproducing) Population
Augmentative Hydrilla BioControl
GRASS CARP
• Sterile (Triploid) Grass Carp Used to Manage Hydrilla
• BUT- They Are Not Selective Feeders
• Can Only be Used in Closed Water Bodies
UF
Hydrilla Bioherbicide
Mycoleptodiscus terrestris(Native Fungal Pathogen)
Fortuitous (Adventive) BioControl
• Regulation of a Weed Population by a Natural Enemy that Has Arrived from Elsewhere WithoutDeliberate Introduction
• No Active Human Involvement
Fortuitous Hydrilla BioControlParapoynx Moth
• Adventive sp. from Asia• Collected in 1976,
Ft. Lauderdale Area• Hydrilla- Principle Host
Plant• Introduced via Aquarium
Trade• Damage to Hydrilla
Minimal & Sporadic ???– Poor BioControl Agent
© H. Clifford
• Midge Discovered in Crystal River 1992
• Identified Dec 1998– Collected in 1959,
Natchitoches, LA– Described 1964– Hydrilla in Louisiana ?– Natchitoches,1973
• Immigrant or Native Species ????
Male
Fortuitous Hydrilla BioControlCricotopus lebetis Sublette
“Ideal” Hydrilla BioControl Agent• Narrow Host Range (=Safety)- Specialists• Damages Vital Plant Tissues (=Individual Effect)• Reproductively Prolific (=Population Effect)• Entire Life Cycle on Submersed Hydrilla• Amenable to Local Conditions (=Climate Match
& Habitat Conditions)• Thrives on Local Hydrilla (Biotype Match)• Protected from Predators (=Endophagous)
Source: T.D. Center, USDA-ARS
The Hydrilla Miner
• Tip- mining Midge- Larvae Feed on Living
Plant Tissue - Rare Occurrence
• Prevents “topping out”• Naturalized in Florida
- No Swarms- Low Dispersal Distance- Easily Mass Reared
Female
Larva
Management Goals• Integrate Miner, Mt & Imazamox = IPM• Eliminate Adverse Effects of Surface Mats• Reduce Reliance on Herbicides• Create More Favorable Habitat