DEVELOPMENTAL DISTURBANCES IN DIFFERENT INSECT ORDERS CAUSED BY AN ECDYSTEROID AGONIST, RH 5849

Experiments with an ecdysteroid agonist, RH 5849 (1,2-dibenzoy-1-tert-butylhydrazine), indicated high effectiveness on Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), Mamestra brassicae L. (Lepidoptera: Noctuidae), Pieris brassicae Hubner (Lepidoptera: Pieridae), and Oncopeltus fasciatus (Dallas) (Heteroptera: Lygaeidae); moderate effectiveness on Phaedon cochleariae (F.) (Coleoptera: Chrysomelidae), Plutella xylostella (L.) (Lepidoptera: Plutellidae), and Neobellieria bullata Parker (Diptera: Sarcophagidae); and low effectiveness on Acyrthosiphon pisum (Harris) (Homoptera: Aphididae). Postembryonic development of P. xylostella and N. bullata was delayed; we observed molting disturbances including premature head capsule apolysis in L. decemlineata, M. brassicae, and P. brassicae, an early first molt in N. bullata, and nymphal-adult intermediates in O. fasciatus. Malformated structures included crochets on M. brassicae and Pieris brassicae, wings on O. fasciatus, and mandibles on N. bullata. Body weight of P. brassicae and.N. bullata was decreased and 0. fasciatus was sterilized. The toxicity on RH 5849 seemed to be strongly species- and stage-dependent. In diet 1,000 ppm RH 5849 had no significant activity on last-instar Periplaneta americana (L.) (Dictyoptera: Blattidae). Fifty ppm of RH 5849 in diet showed no activity during the postembryonic development of Blatella germanica (L.) (Dictyoptera: Blattidae). A concentration of 0.1% RH 5849 on leaves was not effective during the larval stage of A. pisum.