Institute for Integrative Genome Biology

How Mosquitoes Detect Hosts in Human Dwellings

The lab of IIGB/CDVR distinguished professor of entomology Ring Cardé has shown that mosquitoes respond very weakly to human skin odor alone in homes but rather to a fluctuating concentration of carbon dioxide, indicating that a human host is present. The findings could help in the design on new types of mosquito control. 

Cardé explained that mosquitoes, once indoors, conserve their energy by ignoring omnipresent human odor in an unoccupied room. Small increases in carbon dioxide indicate to the mosquitoes the probable presence of a human. This then triggers the mosquitoes to land on human skin.

One take-home message from this work is that studies defining which human odors mediate host finding and which compounds are good repellents need to precisely control exposure to above ambient carbon dioxide – an experimenter entering an assay room quickly elevates the level of carbon dioxide and thereby alters the mosquitoes’ behavior. The research shows that when it comes to feeding on humans indoors, malaria mosquitoes have developed a striking adaptation to how carbon dioxide affects their landing on human targets in response to skin odor.

Larvae of Anopheles gambiae can breed in diverse habitats. This mosquito has evolved to search in human dwellings for blood meals to carry out egg production. The mosquito enters houses throughout the night, peaking around midnight and continuing at a high rate until the early morning hours. Following a blood meal, the mosquito often remains in dwellings until it is ready to lay eggs. Mosquitoes also seek refuge inside human dwellings during the day, taking shelter from high daytime temperatures outside.

Cardé, who occupies the A. M. Boyce Chair in the Department of Entomology, was joined in the study by Ben Webster (first author of the research paper) and Emerson S. Lacey.

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