Mosquitoes suck – literally. They leave irritating bites, transmit diseases and are a general annoyance.
But why do some people seem to be mosquito magnets while others are rarely bitten?
According to Dr. Dan Kline, a research entomologist for the U.S. Department of Agriculture, people have different levels of attractiveness to mosquitoes that can vary from species to species, making it difficult to pin down what is truly going on.
“One size doesn’t fit all,” he said.
What is certain is that all 80 mosquito species in Florida need blood. Both male and female mosquitoes actually feed on sugary substances like plant nectar, but a female requires a blood meal to nourish her eggs, explained Dr. Roxanne Connelly, a University of Florida professor and president of the American Mosquito Control Association.
It takes a female mosquito about 10 to 20 seconds to get the blood they need, she said. After her meal the mosquito lays low for three to four days until she is ready to lay her eggs. Once the eggs have been laid, she wastes no time repeating the process.
“She would be ready right then to go take another blood meal,” Connelly said.
To obtain her meal, the female mosquito needs a way of detecting suitable targets. This is done by way of sensors on mosquitoes’ antennae and palp, Kline said.
Different species have different sensors, he said. Variation in sensors can even occur among members of the same species in a different geographical location.
One of the things these sensory structures are used to detect is carbon dioxide.
Dr. Uli Bernier, a research chemist for the U.S. Department of Agriculture, said a person’s carbon dioxide levels are definitely a factor in a mosquito’s targeting process.
“(The) influence of carbon dioxide makes mosquitoes much more sensitive to picking up other odors,” he said.
Carbon dioxide puts a person on the mosquito’s radar, “but then clearly there are other things that come into play that make some people more attractive,” Connelly said.
During one study using mosquito eggs from Brazil, Kline said he noticed that diet might be connected to a person’s attractiveness to mosquitoes. The Brazilian mosquitoes were biting him far less than local mosquitoes of the same species.
But when a Brazilian researcher exposed her arm to the mosquitoes, their activity increased.
“She stuck her arm in, and they loved it,” he said.
Bernier added that research has shown that individuals who exercise are generally more attractive to mosquitoes.
Diet and exercise both have an influence on metabolism. Different metabolisms determine the chemicals and bacteria on a person’s skin and can potentially make one individual more appealing to a mosquito, Kline said.
Research has also shown that consuming alcohol will make you a more likely target for a mosquito.
“In terms of attraction prior to drinking alcohol, your attractiveness toward mosquitoes does go up and that’s been scientifically proven by a number of studies,” Bernier said.
In one study he was a part of the test subject who got bitten the most also happened to be an alcoholic. The reason drinking alcohol can make you more attractive is because one of the things it breaks down into is acetone, and mosquitoes are attracted to acetone.
While researchers might know how of some of these attractants function they are still learning.
“We certainly don't know it all,” Connelly said.