Host specificity of microsporidia pathogenic to the gypsy moth, Lymantria dispar (l.): field studies in Slovakia [poster]

Eradication of the introduced gypsy moth, Lymantria dispar (L.), from North America was deemed impossible by the mid Twentieth Century, resulting in extensive evaluation and introduction of natural enemies from Europe and Asia for biological control of this serious defoliator. Of the numerous predators, parasites and pathogens studied, the L. dispar pathogens have proven to be the most valuable biological control agents. Of interest due to their ubiquity and diversity are the microsporidia; at least four species are important chronic pathogens of L. dispar. Never recovered from North American gypsy moth populations, the major issue regarding their introduction concerns safety to native nontarget insects. In this study, we evaluated the effects of microsporidia on non-target Lepidoptera when microsporidia were released via ultra low volume sprays into field plots consisting of natural oak stands in Central Slovakia. Coverage of infective spores in a complex environment and, thus, exposure of sympatric non-target species was maximized. We determined, based on host specificity, that three species of the microsporidia are appropriate organisms for release as classical biological control agents of L. dispar. We also evaluated risks that inundative release would pose to nontarget organisms and added to a basic understanding of microsporidian host range.