The role of temperature on in vivo resting spore formation of the aphid-specific pathogen Pandora nouryi (Zygomycota: Entomophthorales) under winter field conditions

Resting spore formation of Pandora nouryi within the host Myzus persicae was investigated in an open cabbage field during two winters: 2007–2008 and 2010–2011. Multivariate correlation analysis of field data revealed that weekly mean temperature was the main abiotic factor governing the probability of resting spore formation in vivo, followed by host density and mean day length, while the effect of season was insignificant. Moreover, the temperature effect on the proportions of resting spore producing cadavers in those aphids infected with P. nouryi was well fit by a logistic equation, and high proportions (0.37–0.95) were found on most of weekly sampling occasions with mean temperatures of less than 10°C. Thus, these resultant analyses support the hypothesis that temperature is the most important abiotic factor controlling P. nouryi resting spore formation in M. persicae under field situations.