Impact of chilling temperature and its exposure period on survival, flight ability and sterility of Aedes aegypti (Linnaeus) (Diptera: Culicidae)

The tiny bloodsucker Aedes aegypti is the primary vector of some fatal diseases like dengue, zika and yellow fever which presents a significant concern for the healthcare sector of Bangladesh. To manage this insect vector, the feasibility of Sterile Insect Technique (SIT) in Bangladesh is being investigated for which quality radio-sterilized males are indispensable. Typically, the sterile males are chilled at low temperature to facilitate their transportation from rear-out-facility to the release site, concurrently to minimize the metabolism, stress and physical damage. In this study, the impact of chilling temperatures (4, 7 and 10 °C) and exposure periods (1, 4, 8 and 24 h) have been studied on the survival, chill-coma recovery rate (CCRR), induced sterility and flight ability of lab-reared local A. aegypti strain. Different chilling temperatures had insignificant effect on CCRR except the 24 h exposure duration. Log-rank test of Kaplan-Meier survival curve showed the significant effect of chilling temperature and duration on the survival. Notably, the chilling temperature of 7 °C exposed for 1 h was found to be optimum in terms of survival. Hence, the induced sterility and flight ability were studied only for this specific temperature and duration, revealing the insignificant effects between the sterile-chilled and sterile but non-chilled A. aegypti. This study underscores the recommendation to chill the mosquitoes at 7 °C for 1 h which will be helpful for the implementation of SIT in Bangladesh.