DEBILITATING EFFECTS OF VIRAL DISEASES ON HOST LEPIDOPTERA

While viral diseases of Lepidoptera are usually recognized for their a bility to kill infected hosts, they may also reduce the fitness of ind ividuals which survive infection. We have surveyed studies in the lite rature in which qualitative characteristics of individuals following t reatment with virus have been evaluated. Most of these studies have in volved nuclear polyhedrosis virus (NPV) and cytoplasmic polyhedrosis v irus (CPV), but several have used granulosis virus (GV), entomopox vir us (EPV), and small RNA viruses. Debilitating effects of viral disease s of Lepidoptera include slower development rates, lower pupal and adu lt weights, reduced reproductive capacity, and shorter adult longevity . These effects were observed more frequently in studies of CPV- than NPV-treated hosts. We evaluate the potential impact of debilitating ef fects of viral disease by comparing the net reproductive rate (R(o)) o f control and treated samples of the host. Studies using CPV and NPV s howed significant reductions in R(o) from debilitating effects as well as from mortality, when compared to R(o) based on mortality alone. Su blethal effects were tested for and confirmed more frequently in studi es using CPVs than those using NPVs. Little evidence exists for dose-d ependent sublethal effects, but in studies involving NPV later instars tended to show stronger effects. (C) 1996 Academic Press, Inc.