Responses by Japanese and Oriental Beetle Grubs (Coleoptera: Scarabaeidae) to Bendiocarb, Chlorpyrifos, and Isofenphos

Abstract

Responses of third stage grubs of Popillia japonica Newman and Anomala orientalis Waterhouse to selected topically applied chemicals were studied. At the LD50, Japanese beetle grubs differed very little in susceptibility to the organophosphates isofenphos or chlorpyrifos. Both materials were 3.6-fold more toxic than bendiocarb at both LD50 and LD90. Isofenphos was more toxic than chlorpyrifos to oriental beetle grubs collected from two locations on Long Island, N.Y. Of the three chemicals, bendiocarb was the most toxic to grubs from Fresh Meadows, Long Island. These results indicate that both species are susceptible to the selected materials, although field observations at Fresh Meadows suggest that other factors such as thatch, insecticide binding, or soil microorganisms may influence insecticidal performance in the field.