Abstract: Knockdown resistance (kdr) is used to describe resistance to DDT and pyrethroid insecticides that result from reduced sensitivity of the nervous system in insects and other arthropods. The voltage-sensitive sodium channels are important action targets of DDT and pyrethroids. Pyrethroids are known to exert their insecticidal effects by altering the function of these channels, and the point mutations of their genes are the primary cause for producing kdr resistance. Kdr resistance has been the subject of sustained research interest for more than 40 years, but the past decade has witnessed significant advances in the identification of the mechanisms underlying kdr resistance at the molecular level. This paper mainly reviews new advances on molecular biology of kdr resistance obtained since 1996, with emphasis on the structure of voltage-sensitive sodium channel subunit, gene mutations associated with kdr resistance among 14 species of pest arthropods and their amino acid sequence polymorphisms. These results can provide new insight into the mechanisms by which pyrethroids modify the function of voltage sodium channels.

Key words: Knockdown resistance, voltage-sensitive sodium channel, pyrethroid, gene mutations