Effect of the synergist,piperonyl butoxide,onthe development of deltamethrin resistance in yellow fever mosquito,aedes aegypti L.(diptera:culicidae)

摘要

The larvae and adults of Aedes aegypti were tested for the potentiol to develop resistance to the synthetric pyrethroid,deltamethrin,alone or a combination of deltmethrin with the synergist,piperonly butoxide (PBO).Alothough continuous larval selection for 40 generations resulted in 703-fold resistance,the resistance in the adults was only 1.3.Similarly,adult selections with deltamethrin showed a resistnce ratio of less than four ofter 40 generations,indicting differential response to deltamethrin selectioninthe two developmental stages of the insect.When the susceptible larvae were subjected to selection pressure of deltamethrin and PBO in the ratio of 1:5 for 20 generations,the speed of selection for deltamethrin resistance slowed down by 60%.The F_(24) larvae obtained from the strain selected with deltamethrin alone were further subjected to selection pressure with synergized deltamethrin,which resulted in 89% reversal in deltamethrin resistance in just one generation.However,long-term selection with the insecticide-cynergist combination returned resistance in just one generation.However,long-term selection,with the insecticide-synergist combination returned resistance close to original levels in 15 generations.The data indicate in the larvae.Implications of the results on the management of larval and adult stages of Ae.aegypti are discussed.