TOXICITY OF PERMETHRIN, AZINPHOSMETHYL, AND METHOMYL TO PHOLETESOR ORNIGIS (WEED) AND PHOLETESOR PEDIAS NIXON (HYMENOPTERA: BRACONIDAE), PARASITES OF THE SPOTTED TENTIFORM LEAFMINER, PHYLLONORYCTER BLANCARDELLA (FABR.) (LEPIDOPTERA: GRACILLARIIDAE)

Abstract

AbstractThe toxicity of the insecticides permethrin, azinphosmethyl, and methomyl to adult Pholetesor ornigis (Weed) and P. pedias Nixon was evaluated in laboratory bioassays. Older P. pedias (2 and 3 days old) were more susceptible than younger parasites (1 day old) to permethrin. Azinphosmethyl was slightly more toxic to female P. ornigis than to male P. ornigis or to P. pedias. There was no consistent difference in the response of adult P. ornigis compared with P. pedias exposed to permethrin or methomyl on treated paper disks. Methomyl was twice as toxic as either azinphosmethyl or permethrin. Male P. ornigis were less susceptible than female P. ornigis to permethrin, but the difference was significant in only one of four populations tested. Male P. ornigis were less susceptible than females to azinphosmethyl. In 1986, populations of P. ornigis which had been exposed previously to pyrethroid insecticides were less susceptible to permethrin than P. ornigis from orchards where pyrethroids had never been applied. The response of both Pholetesor spp. to permethrin varied significantly from 1986 to 1987.