Chen Chun, Feng Ming-Guang
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310029, PR China.
J Invertebr Pathol. 2004 Jul;86(3):117-23. doi: 10.1016/j.jip.2004.05.006.
Epizootics caused by the obligate Entomophthorales pathogen Pandora neoaphidis may result from more than one possible means of fungal dissemination among host aphids, but we hypothesize that wide dispersal of the fungus is most likely to be associated with the flight behavior of migratory alates. We tested this hypothesis in a simulation experiment by assessing the flight capability of Sitobion avenae alates infected with P. neoaphidis and the potential of their post-flight survival, colonization, and mycosis transmission to progeny. A total of 281 alates were inoculated with P. neoaphidis, individually flown for up to 5h and 9km in a computer-monitored flight mill system and then reared for 10 days on wheat seedlings. The infected alates were capable of surviving on average for 2.9 days (range 1-7 days) and leaving 4.6 nymphs prior to deaths. Transmission of fungal infection within progeny colonies occurred after the mother alates died from P. neoaphidis mycosis. The level of contagious infection among the nymphs reached up to 16.8% within 7 days but varied with the survival time of the infected mother alates after flight. Based on stepwise polynomial regression analysis, progeny colony size was highly correlated with the interactions of flight time with both post-flight survival time and the number of nymphs left per alate before death (r2 = 0.997). Progeny mortality on day 5 after colonization was inversely correlated with post-flight survival time (r2 = 0.949) whereas infection on day 7 was correlated with flight distance and an interaction of post-flight survival time with fecundity of the infected alates (r2 = 0.970). Progeny mortality observed on day 10 was merely correlated to mortality observed on day 5 (r2 = 0.946). These results indicate a successful transmission of alate-borne P. neoaphidis to progeny colonies and further support our hypothesis on the means of primary dispersal of aphid epizootics by migratory alates in a geographically wide range.
由专性虫霉目病原体新蚜虫疠霉（Pandora neoaphidis）引起的流行病可能源于真菌在宿主蚜虫间传播的多种可能途径，但我们推测，真菌的广泛传播最有可能与迁飞型有翅蚜的飞行行为有关。我们通过评估感染新蚜虫疠霉的麦长管蚜（Sitobion avenae）有翅蚜的飞行能力以及它们飞行后存活、定殖和将真菌病传播给后代的潜力，在一项模拟实验中对这一假设进行了检验。总共281只麦长管蚜有翅蚜接种了新蚜虫疠霉，在计算机监控的飞行磨系统中单独飞行长达5小时和9公里，然后在小麦幼苗上饲养10天。受感染的有翅蚜平均能够存活2.9天（范围为1 - 7天），并在死亡前产下4.6只若蚜。在母有翅蚜死于新蚜虫疠霉真菌病后，后代群体内发生了真菌感染的传播。若蚜中的传染性感染水平在7天内高达16.8%，但随受感染母有翅蚜飞行后的存活时间而变化。基于逐步多项式回归分析，后代群体大小与飞行时间与飞行后存活时间以及每只有翅蚜死亡前留下若蚜数量的相互作用高度相关（r² = 0.997）。定殖后第5天的后代死亡率与飞行后存活时间呈负相关（r² = 0.949），而第7天的感染与飞行距离以及飞行后存活时间与受感染有翅蚜繁殖力的相互作用相关（r² = 0.970）。在第10天观察到的后代死亡率仅与第5天观察到的死亡率相关（r² = 0.946）。这些结果表明，有翅蚜传播的新蚜虫疠霉成功传播到了后代群体，进一步支持了我们关于迁飞型有翅蚜在地理范围内对蚜虫流行病进行初次传播方式的假设。
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