"Until now, it's only been suspected that mosquitoes bite males—whether they're humans, birds, or other animals—more often than females," says Woodbridge Foster. "Male birds are infected more often than females with the diseases that mosquitoes carry, so it makes sense that mosquitoes bite males more often." (Credit: David Mitchell/Flickr)

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Mosquitoes prefer to bite male birds

Mosquitoes have a sweet tooth for male birds. When it’s time for a meal, they’ll bite males 64 percent of the time and females 36 percent of the time.

Scientists say the findings may help understand how to stem some viruses from spreading to humans.

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The new research is the first step in trying to figure out why mosquitoes bite men more often than women in some parts of the world and vice versa in other areas, says Nathan Burkett-Cadena, assistant professor of entomology at University of Florida.

“Understanding why mosquitoes bite males more often than females may lead to novel strategies for interrupting disease transmission.”

Research like this points scientists in the right direction toward mosquito-borne virus prevention, says Woodbridge Foster, a retired entomology professor at Ohio State University, who was not part of the study.

“In the case of humans, sex- and age-connected risk can be reduced in a number of ways, including immunization, repellents, altering work and non-work habits, and modifying the environment of the most vulnerable.”

More infected male birds

Vector-borne diseases account for an estimated 17 percent of infectious diseases globally, according to the World Health Organization. Malaria, the most deadly vector-borne disease, caused an estimated 627,000 deaths in 2012.

“Until now, it’s only been suspected that mosquitoes bite males—whether they’re humans, birds, or other animals—more often than females,” Foster says. “Male birds are infected more often than females with the diseases that mosquitoes carry, so it makes sense that mosquitoes bite males more often. However, until this study, no one had shown it.”

For the new study, published in Royal Society Open Science, Burkett-Cadena and colleagues went to a swamp near Tampa to collect hundreds of females of three mosquito species known to transmit viruses from birds to humans. Many of the mosquitoes still had blood in their digestive system that came from the animals they bit.

The mosquitoes were crushed to collect the animal blood from their guts which was then screened to determine what type of animal they had bitten. Another test determined the animal’s sex. Through the tests, researchers identified the sex of birds from which mosquitoes fed.

More human men, too?

Now that scientists know mosquitoes suck blood from male birds more than females, they can turn their research attention globally. For example, the human malaria parasite can be found five times more often in men than women in China, according to a 2009 study.

Using the new method, researchers could investigate whether mosquitoes bite men more often than women and if that is the reason Chinese men are more often infected with malaria.

“What if some behavior men are engaging in is exposing them more to mosquitoes?” Burkett-Cadena says. “It’s not that mosquitoes prefer to feed on men, but it’s probably something men are doing.

“If men and women are engaging in different activities that cause them to be bitten by mosquitoes more or less often, then perhaps people can alter their behaviors to reduce their chances of contracting a deadly disease.”

Source: University of Florida

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