RH-5849, A NONSTEROIDAL ECDYSONE AGONIST, DOES NOT MIMIC MAKISTERONE-A IN DYSDERCUS-KOENIGII

The response of final instar nymphs of Dysdercus koenigii to topical a pplication of the non-steroidal ecdysone agonist, RH-5849, was dose de pendent. The candidate compound produced mortality even at moderate do ses, but precocious adult development was not observed. Similar result s were obtained after oral administration or injection. Conversely, in jections of makisterone-A (the principal moulting hormone of Dysdercus ) into 5th instar nymphs resulted in precocious adult development with in 4 days. We conclude that RH-5849 does not mimic makisterone-A, as i s the case with ecdysone, and that toxicity is mediated instead throug h non-endocrine targets in this insect species.