Developmental Disturbances in Different Insect Orders Caused by an Ecdysteroid Agonist, RH 5849

Experiments with an ecdysteroid agonist, RH 5849 (1,2-dibenzoyl-I-tertbutylhydrazine), indicated high effectiveness on Leptinotarsa decemuneata (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 O. 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 .