Susceptibility of Japanese beetle, oriental beetle, and European chafer (Coleoptera: Scarabaeidae) to halofenozide, an insect growth regulator

Abstract

Japanese beetle, Popillia japonica Newman, European chafer, Rhizotrogus (Amphimallon) majalis (Razoumowsky), and oriental beetle, Anomala orientalis Waterhouse, were exposed to an ecdysone agonist, halofenozide, in the egg, 1st instar, and 3rd instar at 1.5, 3, 6, and 12 ppm, respectively, in soil. Species, stage, and physiological condition of larvae affected the response to halofenozide. Japanese beetle was the most sensitive, with maximal response of 1st instar at 3 ppm. First and 2nd instars were more susceptible than were 3rd instar. Sublethal exposure of 1st-instar European chafer and 3rd-instar oriental beetle resulted in dose-dependent accelerated development and successful molts. Field trials are needed in locations where there are mixed populations of scarabs to determine whether the species differences in susceptibility to halofenozide observed in this work will translate to increased relative importance of European chafer.