Laboratory Evidence of the effect of Water Availability on Aedes Mosquito Population Dynamics: A Scoping Review

Emmanuelle Inès Kern, Giovanni Marini, Daniele Da Re, Ilaria Dorigatti

The increasing geographical spread, abundance and activity of invasive Aedes mosquitoes are cause of concern for public health at local and global scales. These species transmit diseases such as dengue, Chikungunya, Yellow Fever, and Zika, which can cause outbreaks in endemic and non-endemic settings. Unlike temperature, whose impact on key entomological traits has been extensively studied, the impact of water availability on Aedes traits and hence population dynamics has been largely overlooked. This scoping review aims to fill this gap by compiling the published laboratory evidence of the effect of precipitation and water availability on the bionomics of invasive Aedes species (including Ae. albopictus, Ae. aegypti, Ae. japonicus, and Ae. koreicus). We found eleven studies investigating the effect of water availability on the bionomics of invasive Aedes mosquitoes, none of which were conducted with Ae. japonicus or Ae. koreicus. The effect of rainfall intensity and duration on the survival and development of Ae. albopictus and Ae. aegypti was investigated by three studies, which showed that heavy and long-lasting precipitation leads to higher immature mortality in both species. The impact of water availability on the survival to adulthood, development, and oviposition behaviour of Ae. albopictus and Ae. aegypti was explored by seven studies. The studies reported higher survival and faster development in water volumes below 2 litres, and that the amount of water contained can favour oviposition, with females laying significantly more eggs in containers that are half full compared to those that are full. An additional two studies explored the relationship between evaporation and adult survival and body size of Ae. albopictus and Ae. aegypti. Evaporation was found to have a detrimental effect on the survival and egg hatching of Ae. albopictus, but not of Ae. aegypti. Interestingly Ae. albopictus was also found to have bigger body sizes when exposed to evaporation. This review provides a summary of the experimental evidence currently published on the effect of water availability on invasive Aedes traits, and highlights how key research questions and knowledge gaps still remain. These should be addressed by future experiments to be able to generate data-driven predictions of the geographical expansion of these species under changing rainfall patterns, and the potential impact of containment strategies.