Chinese scientists make discovery that could impact malaria prevention

Shanghai scientists have discovered that circadian clock genes and environmental factors like light and temperature influence the swarming and mating of anopheline mosquitoes that spread malaria and other human infectious diseases.

The findings may provide insights into innovative vector control strategies targeting insect reproductive behaviors.

A paper about the study that took nearly seven years to complete was published in the world's leading multidisciplinary science journal Science on Friday.

"The study will potentially help researchers gain a better understanding of the mosquitoes' mating mechanisms and the control strategies may be realized through molecular, environmental, and chemical factors regulating the mosquitoes' swarming and mating behaviors," said professor Wang Sibao, a leading researcher on the team from the Shanghai-based Center for Excellence in Molecular Plant Sciences of the Chinese Academy of Sciences (CAS).

The increasing global threat of emerging and reemerging mosquito-borne diseases poses a serious threat to human health. Presently, the control of malaria is heavily reliant on chemical insecticides. But due to the rapid emergence and spread of insecticide resistance, alternative tools are urgently needed to control mosquito populations.

Researchers said that understanding mosquito mating biology is crucial for the implementation of any genetic control programs. However, the molecular mechanisms that modulate the swarming and mating activity in mosquitoes remained unclear.

In this study, researchers used microarray transcriptional analysis to identify genes involved in swarming and mating behaviors by comparing gene expression profiles between swarming and non-swarming male heads of Anopheles mosquitoes.

They found that the circadian master genes period (per) and timeless (tim) are markedly upregulated and rhythmically expressed in swarming male heads compared with non-swarming males. Knockdown of per and tim expression affects mating activity of male mosquitoes in both laboratory and semi-field conditions.

Researchers also found that adverse temperatures and prolonged light exposure during dark periods suppress mating activity. They also found that light and temperature affect mosquito mating as they modulate the expression of tim or per genes.