The female African malarial mosquito “prefers” getting its blood meal from the feet of its sleeping victim. Could the reason be because the buzzing of a mosquito around the head might alert the victim and doom the mosquito with a well-aimed death slap? Yet how does a tiny mosquito find the tender area between the toes during the dark of night?Image may be NSFW.
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In an attempt to eradicate malaria, one of the world’s biggest killers, the Bill and Melinda Gates Foundation has sponsored a great deal of research on malaria and its carrier, the Africa malarial mosquito Anopheles gambiae. The female mosquito requires blood proteins to make eggs that she deposits as rafts on the surface of quiet water, so technically she is the only one that requires a blood meal. And to find that blood, we know that she is fantastically well equipped with a huge array of chemical sensors on and under special hairs covering her antennae, her maxillary palps, and various parts of her proboscis, the elaborately wicked probe that she pokes into a capillary to get the blood.
As it turns out, she has CO2 detectors to locate the ever-expanding cloud of gas exhaled with each breath of the sleeping person. So, at full alert, she follows the ever-increasing concentrations of CO2. Since most CO2 comes from the mouth and nostrils, the head of the sleeper, the dangerous end of the body for her, the mosquito has a problem. But as the insect gets within a couple yards of the victim, it turns out that other odors distracts the mosquito and effectively block the CO2 detectors. The mosquito’s navigation actually switches to another set of sensors that detect bacterial odors, the kind of bacteria that colonize the skin of sweaty feet and toes. Scientists have identified 10 different foot odors, nine of which are incredibly attractive to mosquitoes and five of which effectively block CO2 detection. This research has confirmed that repellents based on blocking CO2 detection are clearly not the answer. What may be much more effective in mosquito control would be traps baited with the delicious scent of smelly feet. With a few such traps in the house, many of the bloodthirsty female Anopheles gambiae would meet their end, thus preventing much human misery and death.
