飞虱虫疠霉继发性感染对桃蚜数量增长的控制作用

用飞虱虫疠霉（Pandora delphaics)“孢子浴”接种的桃蚜(Myzus persicae)无翅成蚜在离体甘蓝菜叶片（65cm^2)上建立蚜群，在不同温度（10－30℃）和湿度（74％－100％RH）的组合条件下任其繁衍，发病和交互感染，以评价该菌的控蚜效果。在25个温，湿度组合处理（8次重复，每重复含3头接种成蚜)中，蚜群均不同程度的发病死亡，在历时30d的观察中，以高温（20－30℃），高湿（95％RH）组合条件下的蚜群发病快且死亡率高，蚜尸上产生的孢子有效地引起若蚜继发性感染。与相同温度下不带菌的对照蚜群相比，次于30℃下，各湿度除个别例外，第8d的控蚜率达30％以上，第20d达80％以上。在10℃和15℃下，控蚜效果一般不如上述较高温度下，且与湿度的关联程度相对较低，但最大控蚜效果均发生在100％RH处理中。结果表明，飞虱虫疠霉用于蚜虫防治的潜力很大，值得深入研究和开发利用。

Role of contagious infection of Pandora delphacis in suppression of Myzus persicae colonies

The colonies of green peach aphid, Myzus persicae, on detached cabbage leaves (8 replicates) were initiated with each including 3 apterae exposed to 'spore shower' of the entomophthoraceous fungus, Pandora delphacis, to evaluate its potential for aphid control. The colonies were then allowed to freely propagate and infect from one to another for mycosis development at different regimes of temperature (10-30 degrees C) and relative humidity (74-100% RH). During a period of 30-day observation, aphid mycosis developed much more rapidly at the regimes of higher temperature (20-30 degrees C) and humidity (> or = 95% RH), at which, nymphs were effectively infected by contacting the conidia discharged from apterous cadavers. The efficacy of P. delphacis for control of M. persicae was easily visible at all regimes considered, despite variation in mycosis-caused mortality. Compared to the increase of M. persicae colony not contaminated with the fungal agent, the efficacy of control at all humidity regimes of 30 degrees C was the best, and it could be > 60% on day 4, and 100% on day 16. Secondary to the best, the increase of colony size at 20 and 25 degrees C was controlled by > 30% on day 8, and > 80% on day 20 at all the humidity regimes with occasional exceptions. The efficacy of control at 10 and 15 degrees C was usually inferior to those at higher temperatures, but to less degree associated with relative humidity. These results indicate that P. delphacis was of high potential for aphid control, deserving further study for practical utilization.