迁移对害虫抗性演化的影响

利用抗性群体遗传模型研究了迁移对害虫抗性演化的影响。模拟结果表明，迁入比例对害虫种群抗性演化的影响存在一定的阈值。若迁入个体全为敏感(SS)纯合子，而其比例又在阈值以下时，这种迁入对抗性演化无延缓作用；迁入比例在阈值以上时，随比例加大，对抗性延缓作用逐渐增强，加大到某一值时，抗性演化可完全被阻止；若迁入个体携有R基因，则迁入比例在阈值以下时，会促进迁入区害虫种群的抗性演化；在阈值以上时，可延缓或完全阻止害虫种群的抗性演化。处理区害虫种群原有个体的迁出，可加强SS个体迁入对害虫种群抗性演化的影响，而使携R基因的个体的迁入影响减弱。以小菜蛾Plutella xylostella为模型昆虫所作的试验结果表明，模型模拟与验证试验的结果具有较好的一致性，说明抗性模拟模型可用于害虫种群的抗性演化预测和分析。

Effect of migration on the evolution of resistance of pest population to insecticides

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.