Pyrethroid Resistance: Importance of the kdr-Type Mechanism

Abstract

Syntheses of photo-stable pyrethroids, such as permethrin, cypermethrin, deltamethrin and fenvalerate, have led to possible agricultural use of pyrethroid class insecticides. Pyrethroid insecticides have very high toxicity to insects and very low toxicity to mammals; there is no problem of environmental contamination because pyrethroids easily decompose in the environment. Due to these favorable characteristics, pyrethroids are expected to be widely used in the areas of both agriculture and public health in the next decade. Development of resistance in pest insects is the only obstacle to the future success of these ideal insecticides. In this review, information regarding the development of pyrethroid resistance is summarized, and the importance of nerve insensitivity to pyrethroids in resistant insects is pointed out. Nerve insensitivity as a mechanism of pyrethroid resistance is controlled in houseflies by a gene termed kdr, and this resistance is therefore called the kdr-type. The kdr-type resistant insects show cross resistance to all kind of pyrethroids, so far synthesized, thus making the ideal insecticides, pyrethroids, impotent.