Larvicidal and immunomodulatory effects of conidia and blastospores of Beauveria bassiana and Beauveria brongniartii in Aedes aegypti

Authors: Ramirez, Jose; Gore, Haley; Payne, Angela; PINTO, SALORRANE - Federal University Of Goias; Weiler, Lina; FERNANDES, EVERTON - Federal University Of Goias; Muturi, Ephantus

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2025
Publication Date: 8/21/2025
Citation: Ramirez, J.L., Gore, H.M., Payne, A., Pinto, S.M.N., Weiler, L.B., Fernandes, E.K.K., Muturi, E.J. 2025. Larvicidal and immunomodulatory effects of conidia and blastospores of Beauveria bassiana and Beauveria brongniartii in Aedes aegypti. The Journal of Fungi. https://doi.org/10.3390/jof11080608.
DOI: https://doi.org/10.3390/jof11080608

Interpretive Summary: As mosquito-borne diseases rise and resistance to insecticides spreads, there is growing interest in fungal biopesticides as efficient tools that can complement current mosquito control strategies. This study tested the insecticidal activity of two insect-killing fungi, Beauveria bassiana and B. brongniartii, in two different forms against mosquito larvae. One form acted quickly, killing mosquito larvae within a few days of application, while the other form was slow-acting but continued to kill mosquitoes as they developed. The fast-acting form triggered stronger mosquito defenses, while the slow-acting form appeared to suppress these responses. These results show that different fungal forms offer unique advantages and could be used together to improve mosquito control. This approach offers a natural, effective tool that complements existing mosquito management methods, especially in areas facing challenges with traditional insecticides.

Technical Abstract: The increasing global burden of mosquito-borne diseases and the widespread development of insecticide resistance in mosquitoes has fueled renewed interest in entomopathogenic fungi as viable alternatives to insecticide-based mosquito control strategies. These fungi produce different types of infective propagules, including hydrophobic conidia and yeast-like blastospores, which differ in structure, mode of infection, and virulence. In this study, we evaluated the larvicidal activity of conidial and blastospore propagules from Beauveria bassiana MBC076 and Beauveria brongniartii MBC397 against Aedes aegypti. Conidia exhibited faster and more potent larvicidal effects compared to blastospores, but the overall survival at seven days post-infection was similar between the two types of propagules. Interestingly, B. brongniartii blastospore infections resulted in significantly higher pupal mortality, suggesting a delayed mode of action. Immune profiling of infected larvae indicated significant induction of antimicrobial effectors such as cecropin, defensin, and attacin, primarily in response to conidial infection. In contrast, blastospore infections led to reduced expression of several prophenoloxidase genes, particularly during infection with B. brongniartii blastospores. These findings indicate that different fungal species and their propagule types exert varying levels of virulence and immune modulation in mosquito larvae. This study provides insights into the infection dynamics of fungal propagules and identifies immune markers that can be leveraged to enhance the efficacy of fungal-based larvicides.