MOLECULAR AND MICROBIOTA RESPONSES TO TEMPERATURE STRESS IN MOSQUITO VECTORS

INTRODUCTION. Climate change is reshaping mosquito distribution, abundance, and vector competence, facilitating the spread of invasive species. Consequently, mosquito-borne diseases are increasing and represent a growing public health threat across tropical, subtropical, and temperate regions. Understanding how mosquitoes respond to temperature fluctuations may support the development of sustainable vector control strategies. This study aimed to assess mosquito responses to different temperature conditions at the genetic level by analysing the expression of genes potentially involved in thermal acclimation. In parallel, we investigated the role of mosquito- associated bacterial communities in this process. Symbiotic bacteria are known to contribute to mosquito fitness; however, temperature stress can alter microbiota composition, potentially affecting host physiology. MATERIALS AND METHODS. Four mosquito species (Anopheles stephensi, Aedes albopictus, Aedes koreicus, and Culex pipiens) were exposed to three temperature regimes (15 °C, 24 °C, and 28 °C) and sampled after 5 and 10 days. Gene expression profiles were analysed in female mosquitoes using RNA-seq, and selected candidate genes involved in metabolic processes, signalling pathways, and transcriptional regulation were validated by qPCR. Bacterial communities were characterised using 16S rRNA gene sequencing (V3–V4 region, MiSeq platform) and qPCR. RESULTS AND CONCLUSION. Comparative analysis revealed both species-specific and shared gene expression responses to temperature. Distinct activation profiles were observed among species, with overall higher gene expression levels in Ae. koreicus, Ae. albopictus, and An. stephensi compared with Cx. pipiens at lower temperatures. Temperature exposure also significantly altered microbiota composition in a species- and temperature-dependent manner. Microbial diversity generally decreased at higher temperatures across all species. Higher diversity was observed at 15 °C in Cx. pipiens after 5 days and in Ae. koreicus after both 5 and 10 days of exposure. Key symbionts showed distinct temperature-dependent dynamics: Asaia increased with temperature, particularly in Ae. koreicus and An. stephensi; Serratia was more abundant in Cx. pipiens, especially at intermediate and higher temperatures; Wolbachia remained dominant in Ae. albopictus and Cx. pipiens, with increasing abundance at higher temperatures. Overall, these findings indicate that mosquito species acclimate to temperature stress through coordinated changes in gene expression and microbiota composition, potentially affecting fitness and distribution. These results provide new insights into mosquito thermal adaptation and may improve understanding of future vector dynamics under climate change.