Pesticide Resistance

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Pesticide Resistance

• Magnitude of the Problem
• Mechanisms
• Case Studies

Physiological Tolerance VS Genetic Resistance
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Resistance by Chem. Group
(Of 450 resistant spp.)
Chlor. Hydrocarbons 60 Organophosphates 47 Carb
amates 14 Pyrethroids 5
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Increasing Cost/Benefit
Chance of Success
Cost of Development
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Declining New Products
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Resistance Natural Phenomenon

• Coevolution plants vs herbivores
• Natural Genetic Variation
• Natural Selection
• diff. reprod. success among genotypes

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EVOLUTION
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Mechanisms of Resistance
Behavioral Resistance
Metabolic Resistance
Target Site Resistance
Decr. Penetration
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Selection for Resistance in Field
Spray
Spray
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Spray
No Spray
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Anopheles Mosquitos
Vectors of malaria Inadvertent targets of agric.
chem.
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10 protein dry wt. esterase!!
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Resistance in Colorado Potato Beetle
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Rat Resistance to Warfarin!
Enz
Vit K Precursor Vit K
Thrombins
(clotting)
Warfarin
Resistance altered enz.
Resistance to Pyrethroids Cotton
budworm Resistance monitoring
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Resistance to Starvation!! Corn Rootworm
Corn Rotation
2 yr Diapause
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Factors Influencing Evol. of Resistance

• Genetic
• Resistant allele freq.
• Dominant vs Recessive
• Previous Evol. Experience
• Life Stage Exposed

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Factors Influencing Evol. of Resistance

• Ecological
• Gen. Per Year
• Immigrants Refugia
• Houseflies in chicken coops
• Roachs on navy ships

KEY Dont Kill all Susceptibles!
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Managing Resistance

• Persistent vs Short-lived Chemical
• Sequence Application (historical)
• Mixtures
• Rotations
• Mosaics

Chemicals only buy time!
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Less is More
Partial Plant Resistance eg. Plant natural
defenses
Biotechnology eg. Tissue-specific
expression insects diverted, not killed can use
with natural enemies
The bugs bat last!