Abstract: Influence of individual migration on the evolution of resistance of pest population to insecticides has been studied based on population genetics by modeling. The simulated results indicate that there is a threshold of migration ratio in the migration of different genotypes influencing the resistance evolution of pest population. If the genotypes of immigration individuals are all susceptible(SS), when the immigration ratio is below the threshold, there is no retarding effect on the evolution of resistance of the pest population, and when the immigration ratio is above the threshold, the delaying effect increases gradually as the immigration increases. The resistance evolution of pest population is entirely prevented when the immigration ratio increases to a certain value. If the genotypes of immigration individuals are all resistant (R gene), and the immigration ratio is below the threshold, then it will accelerate the resistance evolution of pest population. But when the immigration ratio is above the threshold , it will slow down or stop the resistance evolution of the pest population. The emigration of individuals from the insecticidetreated area can enhance the effect of immigration of SS individuals on the resistance evolution and reduce the effect of immigration of the individuals with R gene (including RS and RR individuals) on the resistance evolution. The results from modeling and that from bioassay with Plutella xylostella appear to have a better consistency. It suggests that the resistance simulation modeling might be useful for predicting and analyzing the evolution of resistance of pest population to insecticides.

Key words: the evolution of resistance to insecticide, migration, pest population