Selection, refugia, and migration: Simulation of evolution of dieldrin resistance in Lucilia cuprina (Diptera: Calliphoridae)

Abstract

We simulated changes in allele frequently at the dieldrin resistance locus observed in field populations of Lucilia cuprina (Wiedermann) by using computer models with parameters for selection, refugia, and migration. Dieldrin was introduced to control L. cuprina in Australia in 1955; resistant individuals were first observed at high frequency in 1957. The frequency of resistant individuals has declined since the chemical was withdrawn for control in 1958. Both the increase and decrease phases were simulated. Empirical measurements of fitness, migration, and the number of generations per year are available. Refugia and the number of treatments per year are the most important factors in slowing the evolution of resistance in this system. The simulation showed that, if there is strong overwintering selection against resistance, the evolution of resistance could be showed if part of the population is deliberately left in refugia from insecticide use. The results emphasize that the predictions of general models must be interpreted in a system-specific manner.