Thermal dynamics of vector breeding habitats and their impact on immature survivorship of Anopheles stephensi in Chennai, India

Aquatic temperature influences the development and survival of immature Anopheles stephensi with implications for vector population trends and control strategies under climate change. Temperature was recorded from breeding habitats in Besant Nagar, Chennai, using floatable data loggers, in cemented overhead tank (cOHT), synthetic overhead tank (sOHT), shaded-well (S-Well) and non-shaded well (NS-Well). Hourly temperatures were analyzed across months and seasons. Immature survivorship experiments were carried out in biological incubators simulating habitat temperatures and compared with standard conditions. Adult mosquito longevity was assessed under simulated thatched-roof temperatures. sOHT recorded the highest temperatures, followed by cOHT, with wells recording minimum temperatures. Kruskal-Wallis tests showed significant differences in Hatching rate (HR) and Pupation rate (PR) across habitat temperatures, but not in Emergence rate (ER). Dunn's analysis revealed better immature development under Standard and Well conditions versus cOHT and sOHT. PERMANOVA confirmed temperature's strong influence on development, with cOHT causing the greatest survivorship variation. Adults emerging under cOHT conditions showed higher longevity than sOHT, while the adults which emerged from wells survived longest. This study demonstrates habitat-specific thermal effects on An. stephensi development and survival. Vector control through habitat modification, preventing breeding in overhead tanks, and public awareness are crucial for urban malaria elimination.