Volatiles associated with entomopathogenic fungal spores attract female Anopheles stephensi mosquitoes (Diptera: Culicidae)

Successful control of Anopheline vectors is crucial in controlling malaria 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. Studies have shown that fungi produce many volatiles and they can be used as markers of fungal presence based on their characteristic GC-MS fingerprints (Fiedler et al 2001). Our research studies (George et al., Malaria Journal, submitted) have shown that fungal infection reduces the mosquito’s olfaction and flight behavior and the fungal exposed mosquitoes exhibit reduced propensity to feed, which would reduce malaria transmission. We performed behavioral assays using entomopathogenic fungal spores of Beauveria bassiana and Metarhizium acridum in Y-tubes using unfed female mosquitoes (Anopheles stephensi). Our preliminary results show that the females are attracted to fungal spores and they are able to differentiate between Beauveria spores and other fungal spores. Beauveria spores could kill the mosquitoes in 6-8 days if they were to get infected. We collected volatiles from fungal spores using SPME fibers and analyzed them using GC-MS. The volatile profile of spores that were attractive contain some of the same compounds that have been shown to be attractive to other mosquito species. GC-EAD studies currently being conducted will help zero in on compounds that may contribute to attraction, and may help in improving the efficacy of fungal pathogens as a bicontrol strategy in the field. To our knowledge, this is the first report of mosquito attraction towards fungal spores.