Abstract
In this study, a novel A2′N mutation that confers fipronil resistance was found in the membrane-spanning region M2 of the RDL GABA receptor from fipronil-resistant planthoppers in the heterozygous state. Furthermore, rapid monitoring methods using polymerase chain reaction-restriction fragment polymorphism were employed to detect fipronil-resistant planthoppers carrying the A2′N mutation. It was found that 3-benzamido-N-[4-(perfluoropropan-2-yl)phenyl]benzamides (meta-diamides) comprise a distinct class of RDL GABA receptor antagonists with high insecticidal activity. A membrane potential assay demonstrated that meta-diamides acted on A2′ mutant RDL GABA receptors at the same level as the wild-type RDL GABA receptor. In addition, meta-diamides may act on the M1–M3 intersubunit pocket, whereas cyclodienes and fipronil act on the A2′ residue in the pore formed by M2s. Thus, meta-diamides are expected to be effective against cyclodiene- and fipronil-resistant pests carrying A2′ mutations. Meta-diamides also exhibited high selectivity toward insect RDL GABA receptors.
