Swiss research shows mosquitoes have temperature preferences

Keystone / Felipe Dana

When it is hot, mosquitoes retreat to cool places, says a University of Zurich study. This finding could help prevent mosquito-borne diseases such as malaria, dengue and West Nile virus.

Knowledge of the temperature preferences of mosquitoes helps to better predict the transmission of these diseases, the Swiss National Science Foundation (SNSF) announced on Friday.

This was shown in a new studyExternal link by the University of Zurich published in the Journal of Thermal Biology. For the study, the scientists introduced 100 and 200 female Asian bush mosquitoes (Aedes japonicus) into an outdoor cage equipped with three resting boxes. The first box had a cool temperature of about 18°C, the second box had a warm temperature of about 35°C and the third box had the same temperature as the surrounding environment at about 26°C.

Every two hours, they counted how many mosquitoes were in which box. The researchers found that the mosquitoes preferred the box with the coldest temperature.

Implications for disease prediction

Until now, models predicting the transmission of mosquito-borne diseases have been based on ambient temperatures measured by weather stations. However, these models measure the temperatures at a height of two metres, in the middle of the fields, where there are no mosquitoes. This means that the models might wrongly assume that mosquitoes cannot survive in certain areas because of heat. 

“Thus, based on this average temperature alone, a model could estimate that mosquitoes cannot survive in a certain area because it is too hot, while in reality, by finding cooler microclimates, the mosquito will be quite capable of reproducing and transmitting diseases,” said study author Niels Verhulst.

The results need to be refined with studies over longer periods of time, especially with disease-carrying mosquitoes to see if they prefer warmer or cooler places to rest.