United States – Human body heat is a vital pathway through which mosquitoes locate human beings to feed on them, a new study indicates.
Mosquitos were twice as likely to be attracted to a target in a laboratory if the source produced heat about skin temperature as well as carbon dioxide and human scent, the researchers noted in their recent journal Nature, as reported by HealthDay.
The Power of Body Heat
In other words, body heat is not only a novel sensation that the mosquitoes recognize as a compass towards sourcing human warmth to feed on, the researchers determined.
“What struck me most about this work was just how strong of a cue [body heat] ended up being,” said co-lead researcher Nicolas DeBeaubien, a postdoctoral researcher at the University of California, Santa Barbara (UCSB). “Once we got all the parameters just right, the results were undeniably clear.”
In background notes, researchers noted that mosquitos are one of the leading vectors for the transmission of infectious diseases globally.
The disease caused by mosquito bite kills more than 400,000 people yearly, researchers found out. They are also known to transmit over 100 million times cases of dengue, yellow fever, zika and other diseases in a given year.
The Role of Body Heat in Mosquito Targeting
The insects employ a number of strategies to locate humans, such as their own vision and presumably newly developed sensory organs in the form of breathing and smell, the scientists said.
But, those means are not individually precise. Mosquitos have very little sight, and even if this fails, strong wind or if a human moves swiftly, then it can confuse tracks of chemicals such as the carbon dioxide that is expelled by human lungs.
Therefore, it was assumed that the mosquitos may use another cue to locate people — heat.
To assess the role of body heat, the scientists placed female mosquitos in a container with two pens, one hot and the other colder. Each zone was subjected to the presence of human odors and carbon dioxide to the heat generated from the infrared sources, but only one zone was exposed to infrared radiation at skin temperature.
Increasing the heat by the addition of infrared heat led to a doubling of the insects’ host-seeking activity, as further research showed, and that heat continued to function up to about 2.5 feet.
Heat Alone Isn’t Enough
“But any single cue alone doesn’t stimulate host-seeking activity,” noted senior researcher Craig Montell, a professor of molecular, cellular, and developmental biology with UCSB. “It’s only in the context of other cues, such as elevated CO2 and human odor that [infrared heat] makes a difference.”
However, researchers pointed out that the heat alone did not affect the orientation ability of mosquitos towards a target as assessed through tests.
When studying the biology of mosquitos in detail, people discovered that such pests possess heat-sensing neurons in the tips of their antennae. Cutting off those tips reduced the capability of the mosquitos to feel heat.
Understanding Mosquito Biology for Better Control
Heat-avoidance behavior was also wiped out when TPRA1, a temperature-sensitive protein found in antennae, was blocked, the study found.
They could be used to create a better mosquito trap, by incorporating heat to other signals that would lure the insects, the researchers pointed out.
These results also explain why loose-fitting clothes make it difficult for mosquitoes to bite, according to the researchers. Not only does it prevent the bugs from reaching our skin, but loose clothing also hinders them from identifying heat generated by the body, as reported by HealthDay.
New Possibilities for Disease Prevention
“Despite their diminutive size, mosquitoes are responsible for more human deaths than any other animal,” DeBeaubien noted in a UCSB news release. “Our research enhances the understanding of how mosquitoes target humans and offers new possibilities for controlling the transmission of mosquito-borne diseases.”