新蚜虫疠霉与豌蚜在不同季节性光周期及恒变温组合下的互作反应

在计算机控制模拟的温带地区秋末冬初自然温度与光周期组合条件下，作者对新蚜虫疠霉Pandoraneoaphidis)与豌蚜(Acyrthosiphon pisum)的互作关系进行了研究，试图探索该菌有无与越冬行为有关的前兆反应。时间-剂量-死亡率模型分析显示，恒温20℃下长日照(光照16h/d)和短日照(光照11h/d)对该菌作用于试虫的时间-剂量效应无明显影响，但显著区别于变温(日变幅为5.4-18.9℃，温变速率0.56℃/30min)下相同长短日照处理，变温下长短日照处理之间亦有较显著差异。相同变温下日照长短主要影响试菌对试虫的潜伏期(致死时间)。在变温日照8.0h、9.5h、11.0h、11.5h、12.0h和16.0h下，试菌平均潜伏期分别为15.14d、15.19d、11.79d、13.33d、11.73d和9.21d，明显呈随日照时数增加而递减的趋势即负相关性(a＝15.58，b＝-0.93，r²=0.78，p<0.01)，而恒温日照11 h和16h的平均潜伏期为5.85d和5.97d。镜检所有蚜尸，未发现虫菌体的任何异常现象。结果表明，虽然短日照可延长试菌的潜伏期，但试菌在所有温光组合下均保持着对寄主的有效侵染力，并无越冬的前兆行为反应。作者最后讨论了该菌随寄主迁飞而转移至可生存环境并且无法长期在寄主体外生存的可能性。

INTERACTION BETWEEN THE APHID-SPECIFIC FUNGUS PANDORA NEOAPHIDIS AND THE PEA APHID ACYRTHOSIPHON PISUM AT REGIMES OF VARYING TEMPERATURE AND PHOTOPERIOD SIMULATING VARIABLE SEASONAL PATTERNS

The interaction between the aphid-specific entomophthoralean fungus, Pandora neoaphidis, and the pea aphid, Acyrthosiphon pisum, was investigated in computercontrolled growth chambers at regimes of varying temperature and photoperiod simulating different seasonal patterns in an attempt to reveal the potential preadapting behaviorof the fungus for overwintering. Based on the fitting of the time-dose-mortality model to the experimental data, the time-dose effect pattern was found to be similar between the photoperiods of 16 ∶ 8 and 11: 13 (L ' D) at 20℃, but was significantly different between the constant and daily varying temperatures (5.4-18.9℃ at the rate of 0.56℃per 30 min) and also between the above photoperiods at the same varying temperature.With the varying temperature treatment, the mean incubation time of the fungus on the host (I. E. , mean lethal time postinoculation) was 15.14 d for 8 h of light, 15.19 d for 9.5 h, 11.79 d for 11 h, 13.33 d for 11.5 h, 11.73 d for 12 h, and 9.21 d for 16 h, respectively. This displayed a significantly negative correlation (a=15.58, b=- .93,r²=0.78,p＜0.01). However, the mean incubation periods were nearly identical for 11and 16 h of light at 20℃ (5.85 d and 5.97 d). Abnormal hyphal bodies of the fungus were not found during microscopic examination of all cadavers from all the regimes of temperature and photoperiod. The fungus maintained its infectivity to the host at all theregimes considered and had no preadapting behavior to overwintering. However, the short photoperiods were found to decrease the mean incubation time at the varying temperature that simulated a late autumn or early winter pattern.