Fitness cost of resistance to chlorpyrifos in Lipaphis erysimi (Homoptera: aphididae)

摘要

Genetic and physiological changes conferring resistance to insecticide may induce a fitness cost in the previous adapted population. The present study demonstrates the differences in the fitness of chlorpyrifos resistant and susceptible strains of Lipaphis erysimi. The resistant strain had been selected for three generations in laboratory, and the resistance ratio was ＞ 433- fold compared with the susceptible strain. The F3 of both strains was used in this study. We found that nymphal survival in susceptible strain was significantly higher than resistant strain (50.99±2.79 and 75.02±7.56, respectively). The slower nymphal development associated with the resistant strain in Lipaphis erysimi was also observed. In addition, resistant apterae produced 59.45% fewer nymph than susceptible strain. The resistant strain also exhibit a shorter reproductive period (4.94±0.58 versus 6.95±1.56) and less numbers of nymphs laid per day. These results were discussed together with ecological consideration which shows that the over all iitness of individuals was decreased as the dose tolerance capability of individuals increased after continuous exposure to the chlorpyrifos.