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 gypsy moth, Lymantria dispar (L.), larvae on the entomopathogenic fungus Entomophaga maimaiga Humber, Shimazu et Soper. Time to death, percentage mortality, and numbers and types of spores (conidia and azygospores) produced after host death were evaluated for cadavers of L. dispar larvae that had eaten Quercus rubra L., Acer rubrum L., Pinus strobus L., or Larix kaempferi (Lamb.) Carr. Throughout this study, mortality levels were equivalent across plant species, suggesting a lack of any strong foliar-induced inhibition of conidial penetration of the cuticle. Significantly fewer cadavers of larvae that had eaten A. rubrum produced conidia or azygospores compared with cadavers of larvae that had eaten L. kaempferi , and E. maimaiga developed more slowly in larvae eating A. rubrum . Larvae eating A. rubrum developed more slowly, supporting 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 Japanese isolate produced conidia and this isolate was slower in developing, demonstrating the potential for variability in pathogenesis among pathogen strains.
Hajek, A. E., J.A. A. Renwick and D.W. Roberts. 1995. Effects of larval host plant on the gypsy moth (Lepidoptera: Lymantriidae) fungal pathogen, Entomophaga maimaiga (Zygomycetes: Entomophthorales). Environ. Entomol. 24: 1307-1314.