Abstract: The development of the mycosis of the green peach aphid, Myzus persicae (Sulzer), caused by the entomophthoralean fungus, Zoophthora anhuiensis (Li) Humber, at a dosage of 79～90 conidia/mm2, was investigated at regimes of various temperature constant (10, 15, 20, 25, and 30℃) or fluctuating(1.5～16.6℃and 8.5～20.2℃) and relative humidities (50, 65, 80, 90, 95,100% RH).Each of the 42 batches of aphids exposed to spore shower consisted of 30～60.7dayold nymphs and was placed in an incubator at a given regime after being maintained at 20℃ with nearly saturated humidity for 24 h for initiation of infection. During a 19d period of observation, death of aphids caused by Z. anhuiensis occurred at all regimes and the cumulative mortalities differed greatly among the regimes of temperature (F=7.46, P<0.01) or relative humidity (F=12.54, P<0.01). The optimal temperature for the development of mycosis was 20℃ constant or 8.5～20.2℃ fluctuating daily (12.4℃ on average),at which the mortality increased with relative humidity.Among the regimes of 10～25℃ with 100% RH,the increase in temperature had little effect on the cumulative mortality of aphids but greatly affected the developmental rate of mycosis with LT₅₀s being 8.4，7.1，4.0，and 3.4 days at 10,15,20,and 25℃,respectively.Linear regression of 1/LT₅₀ against temperature suggests a threshold temperature of 1.65℃ for the mycosis development.Production of conidia from aphid cadavers required80% RH at 10～15℃ and at the two temperature-fluctuating conditions,and 90% RH at 20～30℃.Resting spores of the fungus were not found in aphid cadavers from any group of the 42 regimes tested.

Key words: Zoophthora anhuiensis, Myzus persicae, spore shower, development of aphid mycosis, temperature and humidity regimes