Abstract
<title>Abstract</title> <p> <italic>Wolbachia</italic> -based interventions have become a successful biological strategy to reduce dengue virus (DENV) transmission by <italic>Aedes aegypti</italic> . However, whether the protective phenotypes conferred by this symbiont remain stable under environmental stress remains poorly understood. Here, we investigated the impact of sublethal insecticide (deltamethrin) exposure on multiple components of the <italic>Wolbachia</italic> – <italic>Aedes aegypti</italic> –DENV system, including pathogen blocking, cytoplasmic incompatibility, host reproductive traits, symbiont density, and viral diversity. We show that insecticide exposure induces a transient reduction in <italic>Wolbachia</italic> density, which rapidly recovers without compromising DENV blocking, cytoplasmic incompatibility, or reproductive performance. In addition, insecticide exposure has a negligible impact on viral genetic diversity in mosquito saliva. These findings demonstrate the robustness of <italic>Wolbachia</italic> -mediated pathogen blocking under chemical stress and provide evidence that symbiont-based biological control can remain effective under environmentally challenging conditions. </p>