IMPROVEMENT OF A BACULOVIRUS PESTICIDE BY DELETION OF THE EGT GENE

The egt gene of the insect baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) encodes the enzyme ecdysteroid UDP-glucosyltransferase. Expression of egt enables the virus to inhibit molting of its infected host. In this study, we have compared the growth and development of insects infected by viruses with and without a functional egt gene. Our data reveal that, since insects normally stop feeding for both larval-larval and larval-pupal molts, expression of egt prevents the insect from experiencing this feeding arrest. Thus, egt functions to prolong the length of time the insect feeds after infection, with a resultant increase in the weight gain of the insect. We show that deletion of the egt gene significantly improves the pesticide characteristics of AcMNPV. Larvae infected with an egt deletion mutant display considerably reduced feeding and earlier mortality than wild-type AcMNPV-infected larvae.