Recombinant expressing toxin Cyt1Aa: a promising approach for enhancing mosquito control.

Unlabelled: The entomopathogenic fungus provides an eco-friendly substitute to chemical insecticides for mosquito control. Nevertheless, its widespread application has been hindered by its comparatively slow efficacy in eliminating mosquitoes. To augment the potency of against mosquitoes, a novel recombinant strain, -Cyt1Aa, was developed by incorporating the toxin gene into . The virulence of -Cyt1Aa was evaluated against and using insect bioassays. Compared to the wild-type (WT) strain, the median lethal time (LT) for larvae infected with -Cyt1Aa decreased by 33.3% at a concentration of 1 × 10 conidia/mL and by 22.2% at 1 × 10 conidia/mL. The LT for adults infected with -Cyt1Aa through conidia ingestion was reduced by 37.5% at 1 × 10 conidia/mL and by 33.3% at 1 × 10 conidia/mL. Likewise, the LT for adults infected with -Cyt1Aa through cuticle contact decreased by 33.3% and 30.8% at the same concentrations, respectively. Furthermore, the -Cyt1Aa strain also demonstrated increased toxicity against both larval and adult , when compared to the WT strain. In conclusion, our study demonstrated that the expression of toxin Cyt1Aa in enhanced its virulence against mosquitoes. This suggests that expressing Cyt1Aa has potential value for use in mosquito control.

Importance: is a naturally occurring fungus that can be utilized as a bioinsecticide against mosquitoes. Cyt1Aa is a delta-endotoxin protein produced by that exhibits specific and potent insecticidal activity against mosquitoes. In our study, the expression of this toxin Cyt1Aa in enhances the virulence of against and , thereby increasing their effectiveness in killing mosquitoes. This novel strain can be used alongside chemical insecticides to reduce dependence on harmful chemicals, thereby minimizing negative impacts on the environment and human health. Additionally, the potential resistance of against mosquitoes in the future could be overcome by acquiring novel combinations of exogenous toxin genes. The presence of that expresses Cyt1Aa is of significant importance in mosquito control as it enhances genetic diversity, creates novel virulent strains, and contributes to the development of safer and more sustainable methods of mosquito control.