Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
Malar J. 2011 Aug 3;10:219. doi: 10.1186/1475-2875-10-219.
Chemical insecticides against mosquitoes are a major component of malaria control worldwide. Fungal entomopathogens formulated as biopesticides and applied as insecticide residual sprays could augment current control strategies and mitigate the evolution of resistance to chemical-based insecticides.
Anopheles stephensi mosquitoes were exposed to Beauveria bassiana or Metarhizium acridum fungal spores and sub-lethal effects of exposure to fungal infection were studied, especially the potential for reductions in feeding and host location behaviours related to olfaction. Electrophysiological techniques, such as electroantennogram, electropalpogram and single sensillum recording techniques were then employed to investigate how fungal exposure affected the olfactory responses in mosquitoes.
Exposure to B. bassiana caused significant mortality and reduced the propensity of mosquitoes to respond and fly to a feeding stimulus. Exposure to M. acridum spores induced a similar decline in feeding propensity, albeit more slowly than B. bassiana exposure. Reduced host-seeking responses following fungal exposure corresponded to reduced olfactory neuron responsiveness in both antennal electroantennogram and maxillary palp electropalpogram recordings. Single cell recordings from neurons on the palps confirmed that fungal-exposed behavioural non-responders exhibited significantly impaired responsiveness of neurons tuned specifically to 1-octen-3-ol and to a lesser degree, to CO2.
Fungal infection reduces the responsiveness of mosquitoes to host odour cues, both behaviourally and neuronally. These pre-lethal effects are likely to synergize with fungal-induced mortality to further reduce the capacity of mosquito populations exposed to fungal biopesticides to transmit malaria.
化学杀虫剂是全球控制疟疾的主要手段。真菌性昆虫病原体被制成生物农药并作为杀虫剂残留喷雾使用，可以补充当前的控制策略，并减轻对化学杀虫剂产生抗药性的风险。
将白僵菌或绿僵菌的真菌孢子暴露于致倦库蚊，研究暴露于真菌感染的亚致死效应，特别是减少与嗅觉有关的摄食和宿主定位行为的潜力。然后采用触角电位、触须电位和单感器记录技术等电生理学技术，研究真菌暴露如何影响蚊子的嗅觉反应。
白僵菌暴露会导致显著的死亡率，并降低蚊子对刺激物的反应和飞行能力。绿僵菌孢子的暴露会诱导类似的摄食倾向下降，但比白僵菌暴露的速度慢。真菌暴露后的宿主寻找反应减少与触角电生理和触须电生理记录中嗅觉神经元反应性降低相对应。触须上神经元的单细胞记录证实，真菌暴露的行为无反应者对 1-辛烯-3-醇和 CO2 的神经元反应性明显受损，而对 CO2 的神经元反应性受损程度较轻。
真菌感染降低了蚊子对宿主气味线索的反应性，无论是在行为上还是在神经元上。这些亚致死效应可能与真菌诱导的死亡率协同作用，进一步降低暴露于真菌生物农药的蚊子种群传播疟疾的能力。
