Investigating the impact of chilling temperature on male Aedes aegypti and Aedes albopictus survival

In genetic control programmes, including the sterile insect technique (SIT), it is crucial to release insects of the highest quality with maximum survival. It is likely that male mosquitoes will follow the trend of other insects in SIT programmes and be stored, transported and eventually released under chilled conditions. The aim of our study was to investigate the impact of different chilling temperatures on male Aedes aegypti and Ae. albopictus survival by exposing them to a range of temperatures for different durations. Ae. aegypti were found to be less sensitive to the impact of chilling, with only 6°C causing a marginal decrease in survival in comparison to non-chilled controls. Conversely, Ae. albopictus displayed a significantly reduced survival at all chilling temperatures even when exposed for a short time. In both species, longer exposure to low temperatures reduced survival. Our results uncovered that Ae. albopictus are more sensitive to chilling, regardless of the temperature, when compared to Ae. aegypti. Such results indicate differences in thermal tolerances between species and the necessity of conducting experiments on a species by species basis when determining temperature limits for any insect destined for release as part of a genetic control programme.