Department of Bioproduction Science, The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate, Japan.
Department of Agro-environmental Science, Obihiro University of Agriculture & Veterinary Medicine, Obihiro, Hokkaido, Japan.
Sci Rep. 2017 Jun 14;7(1):3476. doi: 10.1038/s41598-017-03720-x.
Entomopathogenic fungi are known to control vector mosquito populations. Thus, understanding the infection dynamics of entomopathogenic fungi is crucial for the effective control of insect pests such as mosquitoes. We investigated the dynamics of Beauveria bassiana s.l. 60-2 infection of Anopheles stephensi by exposing the mosquito to fungus-impregnated filter paper through two infection routes and then comparing the mortality and extent of infection. Fungal development was observed after using this inoculation method with both the tarsus route and the proboscis route, but early mosquito death occurred only after infection through the proboscis route. Fungal hyphae invaded almost all the tissues and organs before or after the death of the host, and fungal invasion of the brain was highly correlated with mortality. Moreover, although all mosquitoes that were alive at various time points after inoculation showed no fungal infection in the brain, fungal infection was detected in the brain in all dead mosquitoes. Our results suggest that fungal invasion of the brain represents one of the factors affecting mortality, and that the proboscis route of infection is critical for the early death of vector mosquitoes.
昆虫病原真菌被认为可以控制病媒蚊虫的种群。因此，了解昆虫病原真菌的感染动态对于有效控制如蚊子等害虫至关重要。我们通过两种感染途径将受浸染的滤纸暴露给感染白纹伊蚊，从而研究了球孢白僵菌 s.l. 60-2 对白纹伊蚊的感染动态，然后比较了死亡率和感染程度。用跗节途径和喙途径接种法观察到真菌的发育，但仅在通过喙途径感染后，蚊子才会早期死亡。真菌菌丝在宿主死亡前或后几乎侵入所有组织和器官，并且真菌对大脑的入侵与死亡率高度相关。此外，尽管接种后不同时间点存活的所有蚊子在大脑中均未显示出真菌感染，但在所有死亡的蚊子中均检测到了大脑中的真菌感染。我们的结果表明，真菌对大脑的入侵是影响死亡率的因素之一，并且感染途径是影响病媒蚊虫早期死亡的关键因素。
