Abstract: By means of fluorescence microscopic and electron scanning microscopic techniques, the conidium germination, infection process and pathogenic effect of Beauveria bassiana on the larvae of Dendrolimus punctatus were observed and tested under conditions of 33 combinations of temperature and humidity. The results show that the relationship between germination velocity(V) of the conidia and temperature(T) was determined as V=(T-4.25)/27.2, where 4.25℃ was the initial temperature, and 27.2 was the effective accumulated temperature in a day for conidium germination. Humidity was the main restrictive factor for the germination and infection of conidia, and temperature and humidity had compensatory and comprehensive effects. Pathogenic effect could occur remarkably under the condition of above 10℃ and 95% relative humidity.

Key words: Beauveria bassiana, Dendrolimus punctatus, Fluorescence microscope techniques, Infection effect, cotton, p-hydroxybenzoic acid, mitochondria, root, phloroglucinol