DIETARY-PROTEIN AND CHLOROGENIC ACID EFFECT ON BACULOVIRAL DISEASE OFNOCTUID (LEPIDOPTERA, NOCTUIDAE) LARVAE

Insecticidal pathogens such as baculoviruses are currently under inten sive development as biorational agents for the control of lepidopteran pests. However, because the efficacy of these orally infective viruse s is influenced by host diet, our ability to use baculoviruses effecti vely in an integrated pest management program requires understanding t he influence of dietary components on the disease process. Nutritional stress caused by differences in the quality (casein or soy) or quanti ty (0-8%) of dietary protein altered the postinfectional course of dis ease caused by Autographa californica M nucelopolyhedrovirus in 2 spec ies of noetuids, Heliothis virescens (F.) and Trichoplusia ni (Hubner) . Lethal times of larvae infected with either the wild-type virus or a recombinant expressing a scorpion toxin (AaIT) derived from this pare nt virus were similarly affected by dietary protein. In general, the h igher the level of dietary protein the shorter the lethal times. Howev er, the influence of protein quality on lethal times depended on the i nsect species tested. The effect of chlorogenic acid on disease depend ed on dietary protein levels. At high protein concentrations, chloroge nic acid decreased speed of kill; whereas, at low protein levels, the phenolic had the opposite effect. The common factor among all treatmen ts was that the faster larvae grew, the faster they died from viral in fection. We suggest that insects that grow faster may support faster r ates of viral replication in infected hosts. From an ecological perspe ctive, it is possible that plants of higher protein content may increa se the potential for the development of baculoviral epizootics in inse ct populations.