Benzoylurea resistance in western flower thrips (Thysanoptera: Thripidae): the presence of a point mutation in .

We examined the susceptibility of field strains (BO-1, BO-2, TO-1, and YH-1) and one laboratory strain (H-1) of the western flower thrip, , to benzoylureas. LC values of novaluron were determined as 0.64 ppm against laboratory strain and 2.1-130 ppm against field strains. In the presence of piperonyl butoxide, a cytochrome P450 inhibitor, the insecticidal activity of novaluron tended to be enhanced. To examine whether point mutations in () discovered in an etoxazole-resistant strain of and a benzoylurea-resistant strain of exist in , the nucleotide sequence of was analyzed. We found a nonsynonymous substitution that corresponded to the location of the mutations found in and in the field strains of but not in the laboratory strain, indicating that this point mutation might be associated with the benzoylurea resistance exhibited by the field strains.