Mechanisms of resistance to insecticides targeting RDL GABA receptors in planthoppers
Lindane and cyclodienes, such as dieldrin and α-endosulfan, represent the first generation of noncompetitive antagonists (NCAs) against the insect RDL GABA receptor. It has been reported that A2′S and A2′G mutations in the membrane-spanning region M2 of the RDL GABA receptor confer resistance to lindane and cyclodienes. Fipronil is a second-generation NCA, but A2′S and A2′G mutations provide a low level of cross-resistance to fipronil. Moreover, a novel A2′N mutation that confers fipronil resistance was found in M2 of the RDL GABA receptors from fipronil-resistant planthoppers in the heterozygous state. Thus, problems are being caused by a worldwide appearance of cyclodiene-resistant pests. And attention must be paid to development of fipronil-resistant planthoppers, such as Sogatella furcifera and Laodelphax striatellus in Japan.