Department of Biology & Biochemistry, University of Bath, Bath, UK.
J Insect Physiol. 2011 Oct;57(10):1341-6. doi: 10.1016/j.jinsphys.2011.06.008. Epub 2011 Jun 25.
During an infection locusts behaviourally fever by seeking out higher environmental temperatures. This behaviour places the pathogen at sub-optimal growth temperatures while improving the efficiency of the immune system, thereby prolonging the lifespan of the host. It is therefore in the interest of the pathogen to either adapt to fever-like temperatures or to evolve mechanisms to interfere with, or inhibit fever. We investigated the behavioural fever response of desert locusts to two fungal pathogens. A prolonged fever was observed in locusts infected with Metarhizium acridum. However, fever was comparatively short-lived during infection with Metarhizium robertsii. In both cases restriction of thermoregulation reduced lifespan. Destruxin A (dtx A) produced by M. robertsii, but not M. acridum has previously been associated with the inhibition of the insect immune system. Injection of dtx A during infection with the fever-causing M. acridum inhibited fever and was particularly effective when administered early on in infection. Furthermore, locusts injected with dtx A were more susceptible to M. acridum infection. Therefore engineering M. acridum isolates currently used for locust biocontrol, to express dtx A may improve efficiency of control by interfering with fever.
在感染期间，群居型蝗虫通过寻找更高的环境温度来表现出“发热”行为。这种行为使病原体处于次优生长温度下，同时提高了免疫系统的效率，从而延长了宿主的寿命。因此，病原体要么适应发热样温度，要么进化出干扰或抑制发热的机制，这符合病原体的利益。我们研究了沙漠蝗对两种真菌病原体的行为性发热反应。感染玫烟色棒束孢（Metarhizium acridum）的蝗虫表现出长时间的发热，但感染罗伯茨绿僵菌（Metarhizium robertsii）时发热相对短暂。在这两种情况下，体温调节受限都会缩短寿命。罗伯茨绿僵菌产生的破坏素 A（dtx A）以前与昆虫免疫系统的抑制有关，但玫烟色棒束孢不产生这种物质。在引起发热的玫烟色棒束孢感染期间注射 dtx A 会抑制发热，并且在感染早期注射时效果特别好。此外，注射 dtx A 的蝗虫更容易感染玫烟色棒束孢。因此，对目前用于蝗虫生物防治的玫烟色棒束孢分离株进行工程改造，使其表达 dtx A，可能会通过干扰发热来提高控制效率。
