Strain-specific pathogenicity and subversion of phenoloxidase activity in the mosquito Aedes aegypti by members of the fungal entomopathogenic genus Isaria

Authors: Ramirez, Jose; Muturi, Ephantus; Dunlap, Christopher; Rooney, Alejandro - Alex

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2018
Publication Date: 7/2/2018
Citation: Ramirez, J.L., Muturi, E.J., Dunlap, C.A., Rooney, A.P. 2018. Strain-specific pathogenicity and subversion of phenoloxidase activity in the mosquito Aedes aegypti by members of the fungal entomopathogenic genus Isaria. Scientific Reports. doi:10.1038/s41598-018-28210-6.
DOI: https://doi.org/10.1038/s41598-018-28210-6

Interpretive Summary: Development of alternative methods of mosquito control are becoming more pressing given the rapid evolution of insecticide resistance and the rise of new and re-emergent vector borne pathogens affecting public health. Fungal-based biopesticides represent potential alternative methods of vector control given their benefits as environmentally friendly alternatives to chemical pesticides, and their effectiveness at infecting insects on contact rather than requiring oral ingestion. This study evaluated the pathogenicity of several fungal isolates from the genus Isaria against the yellow fever mosquito Aedes aegypti. Two fungal entomopathogens were found to be highly pathogenic while other three presented moderate virulence against the adult mosquito. In addition, there is evidence of suppression of the mosquito responses to the infection by the invading fungi. This study provides new insights into mosquito-fungal interactions which could facilitate the development of more effective fungal-based biocontrol strategies.

Technical Abstract: Development of alternative methods of mosquito control are becoming more pressing given the rapid evolution of insecticide resistance and the rise of new and re-emergent vector borne pathogens affecting public health. Fungal-based biopesticides represent potential alternative methods of vector control given their benefits as environmentally friendly alternatives to chemical pesticides, and their effectiveness at infecting insects on contact rather than requiring oral ingestion. This study evaluated the susceptibility of Ae. aegypti mosquitoes to a range of entomopathogenic fungal isolates from the genus Isaria. We observed a diverse variation in the virulence of the Isaria isolates tested, with two isolates showing high pathogenicity towards adult mosquitoes. Mosquito susceptibility to fungal infection was further corroborated through the molecular quantification of fungal loads and the transcript evaluation of a fungal-specific pathogen recognition molecule in the mosquito body. Moreover, quantitative analysis of transcript abundance coupled with enzymatic assays revealed isolate-specific subversion of the melanization cascade, an important immune response component. Our study contributes important new insights for a better understanding of fungal-mosquito interactions.