Efficacy of a Baculovirus Pesticide Expressing an Eclosion Hormone Gene

There is considerable interest in the possibility of using insect hormones or hormone regulatory proteins in conjunction with microbial delivery systems as a means of controlling insect pests. We have employed Autographa californica nuclear polyhedrosis virus (AcMNPV) to express a Manduca sexta (L.) cDNA encoding eclosion hormone (EH) to explore the effects this hormone might have during infection in larvae. AcMNPV naturally blocks molting of its insect host by expression of an ecdysteroid UDP-glucosyltransferase (egt) gene. EH-expressing viruses which either possessed or did not possess an intact egt gene were tested. M. sexta EH produced by recombinant viruses elicited eclosion behavior when injected into pharate Spodoptera frugiperda (J.E. Smith) pupae. The presence of the EH gene reduced the infectivity of the virus slightly in neonate S. frugiperda. Expression of the EH gene during infection of late instar S. frugiperda larvae had neither a positive nor a negative effect on the ability of AcMNPV to limit insect feeding or hasten death. No differences in behavior were observed in larvae infected with EH-recombinant versus wild-type virus. (c) 1992 Academic Press, Inc.