Micro-evolutionary change in relation to insecticide resistance in the peach-potato aphid, Myzus persicae

1. Phenotypic diversity is the fuel that powers evolution. 2. Asexual organisms rely on mutation whereas sexual organisms combine mutation with recombination. 3. Few organisms provide examples of species that are both sexual and asexual, but aphids do. 4. To examine evolution on perceptible timescales requires strong evolutionary forces and, as Darwin noted, agricultural practices provide strong selection. In the case of aphids, insecticides provide a considerable force in the elimination of genotypes. 5. Insecticide resistance in Myzus persicae (Sulzer) has arisen independently through point mutation and gene amplification on a number of occasions and at different times. Resistance to organophosphates, pyrethroids, and pirimicarb (a dimethyl carbamate) is now widespread. 6. In this paper, we examine these three elements: sexual recombination, clonal expansion, and insecticide selection in the peach-potato aphid M. persicae in relation to the evolution of insecticide resistance and survival of the fittest clone.