Temperature and Moisture Relations of Sporulation and Germination by Entomophaga maimaiga (Zygomycetes: Entomophthoraceae), a Fungal Pathogen of Lymantria dispar (Lepidoptera: Lymantriidae)

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Abstract
Temperature and moisture relations for conidial sporulation and germination of Entomophaga maimaiga, an Asian fungal pathogen of gypsy moth, Lymantria dispar (L.), were studied in the laboratory. Germination and sporulation occurred between 2 and 25°C with maximal rates between 20 and 25°C. In 50% of cadavers incubated at 20°C, sporulation began within 17.0 h of the hosts' deaths. Spore production and release readily occurred at 95–100% RH, but only limited spore production was seen at 70% RH, and very few spores were produced or released at 50% RH. Germination was delayed by constant light compared with a rapid response under dark conditions: at 20°C, 50% germination occurred in 3.4 h in the dark, but 9.0 h were required in the light. Conidia required free water for germination. Conidiophores did not develop with constant exposure to 30°C. Conidia could survive relatively short exposures to 30°C; >85% of conidia survived ≤6 h of exposure to 30°C. E. maimaiga protoplasts inside infected insects were more resistant to higher temperatures: E. maimaiga completed development in 30% of cadavers despite an exposure period of 48 h at 30°C.