1. The evolution of Insecticide Resistance How it happens How to stop it happening? John McKenzie University of Melbourne

2. Adaptation A mechanistic understanding of the role of natural selection in evolution

3. Evolution – A (very) simple summary Differences between individuals (Phenotype) VariationHeritable component to differences (Genotype) SelectionIndividual phenotypes (genotypes) have different survivorship and/or fertility ChangeIncrease (decrease) of phenotypes (genotypes) in a population

4. The Advantage of Insecticide Resistance as a System to Study Adaptation The selective agent is known The biochemical/physiological/molecular basis of selection is understood Relative fitness differences are large Can measure differences in the laboratory and field Evolution is rapid

5. Three Questions for Today’s Talk What is the genetic basis of insecticide resistance? How does selection occur? Can we use this knowledge to delay the onset of resistance

6. Answers to these Questions GeneticsSingle Gene (++, R+, RR) SelectionActs in a concentration-dependent manner DelayYes

7. Resistance Fitness Sets (Selection) Insecticide Absent Insecticide Present ++ > R+ > RR ++ ≤ R+ ≤ RR SusceptibleResistant Susceptible Resistant

8. Dosage Mortality Lines (Idealised) ++R+ RR 100 Mortality (Probit Scale) 0 AB LOG (Insecticide Concentration)

12. History of Field Resistance for Australian Sheep Blowfly Control DieldrinDiazinonCyromazine Introduced195519571978 Resistance Observed 19571965Not yet GeneticsRdl (V)Rop-1(IV)?

13. Life Cycle of Australian Sheep Blowfly EmergenceAdults (protein feed) & Mate Metamorphosis Females deposit eggs on sheep Pupation in soil Wandering larvae fall from sheep Larvae Develop

21. Relative Viability with Time after Treatment

22. Can we use this knowledge to delay resistance?

24. Is it possible to generate field type resistance in the laboratory?

25. Selecting Single Gene Resistant Mutants Expose susceptible flies to a mutagen Mate to untreated susceptible flies Expose offspring to lethal concentration of Insecticide Survivors are possible resistant mutants (Re test)

26. Results of Laboratory Selection DieldrinDiazinon Resistance due toRdlRop-1 Molecular ChangeSusceptible Resistant Point Mutation Serine alanine Susceptible Resistant Point Mutation Glycine Aspartic Acid Relative to Natural Resistance Same

27. Levels of Resistance LC 100 R+ LC 100 ++ For Larvae

28. Experimental Square-Wave Delivery

30. The Evolution of Insecticide Resistance (A Cross-Disciplinary Approach) Applied Outcomes Chemical Kinetics Molecular Analysis Biochemical Analysis Population Biology/Ecology Genetic Analysis Population Genetics and Evolutionary Principles