Insects and Disease: Mosquitoes and Their Purpose [IN-DEPTH]

Just about every summer block party has a certain persona non grata who shows up and makes the experience less pleasant for everyone. Regardless of where you live, it's usually the same uninvited guest -- the mosquito. After all, this is a creature with 3,500 different species, some of which live on every continent. There are, for instance, so many in the Arctic that their swarms can choke caribou. This more-than-pesky insect is responsible for at least one million deaths a year due to the spread of disease. All that said, it's hard to imagine what their redeeming qualities are.

It's a sentiment shared by scientists too, like insect ecologist Steven Juliano, of Illinois State University, in Normal. Juliano studies the patterns of disease carriers. "It's difficult to see what the downside would be to removal, except for collateral damage," said Juliano, reflecting on the possibility of a world without mosquitoes. The larvae are nutrient-rich, spending the first four to six weeks of their lives underwater, before they mature and go in search of blood to fertilize their eggs and start the entire cycle over again.

So our blood is a bit more prized by them than we might think. How do they go about finding a target? Their hunting is more specialized than you might imagine, and there are ways you can make yourself more of a target to the proboscis of a hungry-enough mosquito. The amount of carbon dioxide given off when you breathe and sweat puts you on their radar  -- as does movement and body temperature, which a mosquito organ called the maxillary palp can detect from 164 feet away.

However, up to 85% of their decision to bite you is due to your own genetics. Uric acid triggers their sense of smell, as does lactic acid produced by your sweat glands. Those with type O blood tend to be bitten twice as often as those with type B, due to higher concentrations of chemicals on the skin that reveal their blood type. Having a beer at that block party could make you a favored mark, although the reasons remain unclear.

As we're currently living in what many have deemed the next great extinction event, plenty of evidence has been left behind showing how disrupted ecosystems look. A prime example is the improvement of Yellowstone Park after gray wolves were reintroduced. Would removing mosquitoes from the planet have an adverse effect on the ecosystem? Already, efforts have been extended to obliterate the insects entirely in order to stem the spread of malaria and West Nile virus, diseases that severely afflict African nations. If the Arctic is any indication, the swarms that feed off caribou control herds' travel routes. Caribou move toward the wind to fend off mosquitoes, keeping much of the land from being overrun and trampled by the herds.

How they can help elsewhere is a good question, but perhaps we should be careful what we wish for. "They don't occupy an unassailable niche in the environment," according to entomologist Joe Conlon from the American Mosquito Control Association. "If we eradicated them tomorrow, the ecosystems where they are active will hiccup and then get on with life. Something better or worse would take over."

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