Mosquitoes can also be found via your body heat

MONDAY, Aug. 26, 2024 (HealthDay News) — Body heat is an effective way for mosquitoes to find people to bite, a new study shows.

Mosquitoes were twice as attracted to a target in the laboratory when the source emitted heat on the order of human skin as well as carbon dioxide and human odor, researchers recently reported in the journal Nature.

The researchers concluded that body heat is a recently documented sense that mosquitoes use to locate humans.

“What impressed me most about this work was how strong the cue (body heat) ultimately was,” said co-leader Nicolas DeBeaubien, a postdoctoral fellow at the University of California, Santa Barbara (UCSB). “Once we got all the parameters right, the results were undeniably clear.”

Mosquitoes are one of the most common vectors of infectious diseases worldwide, researchers explained in background information.

Researchers say more than 400,000 people die each year from mosquito-borne malaria. The insects also spread more than 100 million cases of dengue fever, yellow fever, Zika and other diseases each year.

According to researchers, the insects use a variety of different means to find people. These include their eyesight and sensors that they have developed to detect the air they exhale and the smell of people.

However, these remedies are not accurate in detail. Mosquitoes are known to have poor eyesight, and strong winds or rapid movements of a person can cause them to lose their ability to track chemical traces such as carbon dioxide from the air we breathe.

Therefore, the researchers hypothesized that mosquitoes may use another method to detect humans: body heat.

To test the importance of body heat, researchers placed female mosquitoes in a cage divided into two zones. Each zone was exposed to human odors and carbon dioxide, but only one zone was also exposed to infrared radiation, which produced heat similar to skin temperature.

The researchers found that the additional infrared heat doubled the insects’ host search and that the heat continued to be an effective means of detecting humans at a distance of up to about 75 centimeters.

“But a single cue alone does not stimulate host-seeking activity,” noted lead researcher Craig Montell, a professor of molecular, cellular and developmental biology at UCSB. “Only in the context of other cues, such as increased CO2 levels and human odor, does (infrared heat) make a difference.”

In fact, tests showed that heat alone had no effect on the mosquitoes’ ability to find a target, the researchers found.

By studying the biology of mosquitoes more closely, researchers found that the pests have heat-sensitive neurons at the ends of their antennae. By cutting off these tips, the mosquitoes lose their ability to sense heat.

The results showed that blocking a temperature-sensitive protein in the antennae called TPRA1 also eliminated the mosquitoes’ sensitivity to heat.

These findings could be used to build a better mosquito trap by combining heat with other stimuli that attract the pests, the researchers say.

These findings also explain why loose-fitting clothing prevents mosquito bites, the researchers say. Not only does it stop the insects from getting to our skin, it also prevents them from finding our body heat.

“Despite their small size, mosquitoes are responsible for more human deaths than any other animal,” DeBeaubien noted in a UCSB press release. “Our research improves the understanding of how mosquitoes attack humans and offers new opportunities to control the transmission of mosquito-borne diseases.”

More information

The U.S. Centers for Disease Control and Prevention has additional information on mosquito-borne diseases.

SOURCE: University of California, Santa Barbara, press release, August 22, 2024