Fisher Joanna J, Castrillo Louela A, Donzelli Bruno G G, Hajek Ann E
Department of Entomology, Cornell University, Ithaca, NY 14853-2601.
School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY 14853-5904.
J Econ Entomol. 2017 Aug 1;110(4):1451-1459. doi: 10.1093/jee/tox124.
In several insect systems, fungal entomopathogens synergize with neonicotinoid insecticides which results in accelerated host death. Using the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), an invasive woodborer inadvertently introduced into North America and Europe, we investigated potential mechanisms in the synergy between the entomopathogenic fungus Metarhizium brunneum Petch and the insecticide imidacloprid. A potential mechanism underlying this synergy could be imidacloprid's ability to prevent feeding shortly after administration. We investigated whether starvation would have an impact similar to imidacloprid exposure on the mortality of fungal-inoculated beetles. Using real-time PCR to quantify fungal load in inoculated beetles, we determined how starvation and pesticide exposure impacted beetles' ability to tolerate or resist a fungal infection. The effect of starvation and pesticide exposure on the encapsulation and melanization immune responses of the beetles was also quantified. Starvation had a similar impact on the survival of M. brunneum-inoculated beetles compared to imidacloprid exposure. The synergy, however, was not completely due to starvation, as imidacloprid reduced the beetles' melanotic encapsulation response and capsule area, while starvation did not significantly reduce these immune responses. Our results suggest that there are multiple interacting mechanisms involved in the synergy between M. brunneum and imidacloprid.
在几种昆虫系统中，真菌性昆虫病原体与新烟碱类杀虫剂协同作用，导致宿主加速死亡。我们以亚洲长角天牛（Anoplophora glabripennis (Motschulsky)）为研究对象，它是一种无意间被引入北美和欧洲的入侵性木蛀虫，我们研究了昆虫病原真菌布氏绿僵菌（Metarhizium brunneum Petch）与杀虫剂吡虫啉协同作用的潜在机制。这种协同作用的一个潜在机制可能是吡虫啉在施用后不久就会阻止昆虫取食。我们研究了饥饿是否会对接种真菌的甲虫死亡率产生与吡虫啉暴露类似的影响。通过实时定量聚合酶链反应（PCR）来量化接种甲虫体内的真菌载量，我们确定了饥饿和农药暴露如何影响甲虫耐受或抵抗真菌感染的能力。我们还量化了饥饿和农药暴露对甲虫包囊化和黑化免疫反应的影响。与吡虫啉暴露相比，饥饿对接种布氏绿僵菌的甲虫存活率有类似的影响。然而，这种协同作用并不完全是由于饥饿，因为吡虫啉降低了甲虫的黑化包囊反应和包囊面积，而饥饿并没有显著降低这些免疫反应。我们的研究结果表明，布氏绿僵菌和吡虫啉之间的协同作用涉及多种相互作用的机制。
