EFFECTS OF LARVAL HOST-PLANT ON THE GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) FUNGAL PATHOGEN, ENTOMOPHAGA-MAIMAIGA (ZYGOMYCETES, ENTOMOPHTHORALES)

We investigated the effect of species and age of foliage eaten by gyps y moth, Lymantria dispar (L.), larvae on the entomopathogenic fungus E ntomophaga maimaiga Humber, Shimazu et Soper. Time to death, percentag e mortality, and numbers and types of spores (conidia and azygospores) produced after host death were evaluated for cadavers of L. dispar la rvae that had eaten Quercus rubra L., Acer rubrum L., Pinus strobus L. , or Larix kaempferi (Lamb.) Carr. Throughout this study, mortality le vels were equivalent across plant species, suggesting a lack of any st rong foliar-induced inhibition of conidial penetration of the cuticle. Significantly fewer cadavers of larvae that had eaten A. rubrum produ ced conidia or azygospores compared with cadavers of larvae that had e aten L. kaempferi, and E. maimaiga developed more slowly in larvae eat ing A. rubrum. Larvae eating A. rubrum developed more slowly, supporti ng a hypothesis that host stress negatively influences development of this fastidious pathogen. Although Q. rubra secondary plant compounds are known to, fluctuate as leaves develop during spring, pathogenicity attributes showed no concurrent trend in variation. In comparing 4 of the fungal isolates tested, fewer cadavers of larvae killed by one Ja panese isolate produced conidia and this isolate was slower in develop ing, demonstrating the potential for variability in pathogenesis among pathogen strains.