不同温湿度组合对安徽虫瘟霉诱发桃蚜病害的影响

Impact of temperature and humidity combinations on development of mycosis in Myzus persicae with the entomophthoralean fungus, Zoophthora anhuiensis

用孢子浴方法 ,对 4 2批次桃蚜Myzuspersicae (30～ 6 0头 /批 )接种大剂量 (孢子 79～ 90个 /mm2 )安徽虫瘟霉Zoophthoraanhuiensis的分生孢子 ,在 2 0℃下保湿 2 4h后转入不同温度(10℃、 15℃、 2 0℃、 2 5℃、 30℃及自然变温 1 5～ 16 6℃和 8 5～ 2 0 2℃ )和湿度 (50 %、 6 5%、80 %、 90 %、 95%及 10 0 %RH)的组合条件下观察桃蚜的反应。结果表明 ,各组合条件下的桃蚜均能发病死亡 ,而且累计死亡率的显著差异存在于不同温度 (F =7 4 6 ,P <0 0 1)和湿度间 (F=12 54,P <0 0 1)。最适发病的温度为恒温 2 0℃和变温 8 5～ 2 0 2℃ (日均温 12 4℃ ) ,死亡率随湿度升高而增大。在 10～ 2 5℃和 10 0 %RH的组合中 ,温度的变化几乎不影响桃蚜的累计死亡率 ,但影响发病速率 ,在 10℃、 15℃、 2 0℃和 2 5℃下的致死时间LT50 值分别为 8 4天、 7 1天、4 0天和 3 4天。回归分析表明 ,在 10 0 %RH下安徽虫瘟霉诱发桃蚜发病的起始温度为 1 6 5℃。在 10～ 15℃及自然变温下 ,病死蚜尸顺利产孢的湿度为 80 %RH ;而在 2 0～ 30℃下 ,蚜尸产孢的湿度为 90 %RH。在所有温湿组合的蚜尸中未见安徽虫瘟霉的休眠孢子发生。

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/mm 2, 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 7 day 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 LT 50 s being 8 4,7 1,4 0,and 3 4 days at 10,15,20,and 25℃,respectively.Linear regression of 1/LT 50 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.