Abstract
Two point mutations, Leu1014 to Phe and Met918 to Thr, located in the domain II region of the para-type voltage gated sodium channel, confer knockdown resistance (kdr) to pyrethroid insecticides in several insect species. PCR amplification of this region in a pyrethroid-resistant and pyrethroid-susceptible strain of Aphis gossypii and use of a restriction fragment length polymorphism assay on PCR products (PCR-RFLP) provide the first direct evidence of the Leu1014 to Phe kdr mutation in a field isolate of A. gossypii.
