The males of a disease-carrying mosquito species are attracted to people, even though only the females drink our blood. This suggests the males might hover around humans to pick up mates.
Researchers have previously observed male Aedes aegypti mosquitoes mating with females near people, but it is unclear whether the males, which feed on nectar, are attracted to people or simply drawn towards the blood-drinking females. Female mosquitoes find people using cues such as body odour, carbon dioxide and body heat.
and at the University of Melbourne in Australia and their colleagues recruited 11 volunteers to stand at one end of a 3-metre-long tent, one at a time, while 100 male A. aegypti mosquitoes were released into the tent. Cameras were used to record where the mosquitoes were every 20 seconds for 30 minutes.
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The researchers found that no mosquitoes flew around or landed in the end of the tent without a person, while roughly five mosquitoes flew around or landed on the person, on average, at any time throughout the experiment.
To test whether male mosquitoes are more attracted to certain people, the researchers placed two people at opposite ends of the tent and released either 100 male or 50 female mosquitoes into the tent. They carried out 20 tests with different pairs of participants from a group of five people. This revealed that male and female mosquitoes were preferentially attracted to the same people, although males had weaker preferences than females.
鈥淚t鈥檚 clear that the male A. aegypti mosquitoes are very interested in people and have similar preferences to females,鈥� says Ross. 鈥淲e can鈥檛 say for certain that male mosquitoes evolved this trait specifically to gain a mating advantage, but it鈥檚 a strong possibility.鈥�
In another experiment, volunteers wore a commercial mosquito repellent on their skin. The male mosquitoes were completely deterred from hovering around or landing on them. Repellents work by masking carbon dioxide and other chemicals that attract mosquitoes, so this result suggests males are attracted by similar cues to females.
鈥淣o one鈥檚 really tested how repellents worn on the skin may affect male mosquitoes because they鈥檙e not the ones that bite,鈥� says Ross.
If we can pinpoint the exact cues that repel and attract male mosquitoes to people, this could help us improve methods for controlling mosquito populations, such as releasing sterile male mosquitoes, says Paris.
鈥淭he study provides valuable insights into the factors that influence male mosquito attraction to humans, which could inform the development of new mosquito control strategies,鈥� says at the London School of Hygiene & Tropical Medicine.
bioRxiv
