Environmental contamination of egg masses as a major component of transgenerational transmission of gypsy moth nuclear polyhedrosis virus (LdMNPV)

Abstract

Gypsy moth egg masses acquired most nuclear polyhedrosis virus (NPV) inoculum from their environment during, or within 3 days of, oviposition in contaminated habitats. Moths fed a sublethal NPV dose as second instars did not transmit infective virus to progeny. Precipitation subsequent to oviposition was not implicated in environmental contamination of egg masses. When adult females from a high-density population, in which an NPV epizootic occurred, were site-switched for oviposition with females from a moderate-density population, with moderate levels of NPV mortality, the deployment site, not the parental population, was the most important factor influencing NPV infection rate among their progeny. These experiments suggest that in NPV-contaminated sites, environmental contamination of egg masses, rather than transovum transmission from infected parents to progeny, is a more important means of transmission of NPV from one generation to the next.