If you have always suspected that you might just be a mosquito magnet (招蚊子的人),scientists now have evidence for you: Mosquitoes indeed are attracted to certain humans more than others, according to a new study.
A research team at Rockefeller University sought to identify why certain people seem to draw more mosquitoes than others. Over the course of three years, researchers asked a group of 64 volunteers to wear nylon stockings on their arms for six hours a day over multiple days. Maria Elena De Obaldia, the study’s first author, constructed a glass container in which researchers put two of the stockings. The study team then released yellow fever mosquitoes into the container and observed which stocking drew more insects.
This test allowed researchers to separate study participants into mosquito magnets, whose stockings drew lots of mosquitoes, and low at tractors, who didn’t seem attractive to the insects. The scientists examined carefully the skin of the mosquito magnets and found 50 molecular compounds (分子化合物) that were higher in these participants than the others.
“We didn’t hold certain expectations about what we would find,” said Vosshall, one of the researchers. But one difference was particularly distinctive: The mosquito magnets had much higher rates of carboxylic acid (羧酸) on their skin than the low at tractors. Carboxylic acids are found in sebum, the oily substance that creates a barrier and helps protect our skin.
“The carboxylic acids are large molecules,” Vosshall explained. “They’re not that smelly by themselves,” she said. But beneficial bacteria on the skin chew on these acids that produce the characteristic smell of humans, which may be what attracts mosquitoes, according to Vosshall.
Carboxylic acids are just one piece of the puzzle in explaining how the annoying insects might choose their targets. Body heat and the carbon dioxide we release when we breathe also attract mosquitoes to humans.
Scientists still don’t know why carboxylic acids seem to attract mosquitoes so strongly. The next step might be to explore the effects of reducing carboxylic acids on the skin.
12. Why did the researchers carry out the test in the container?
A.To free people from mosquitoes. | B.To identify mosquito magnets. |
C.To distinguish certain mosquitoes. | D.To better attract other insects. |
13. What is the fourth paragraph mainly about?
A.The feature of human skin. | B.The definition of acid. |
C.The expectation of the researchers. | D.The finding of the study. |
14. What makes carboxylic acids smelly?
A.Beneficial bacteria. | B.Body heat. |
C.Carbon dioxide. | D.Human sweat. |
15. What can we infer about mosquito magnets from the text?
A.They never wear stockings in summer. | B.They feature higher body temperature. |
C.Their root cause has remained unclear. | D.Their daily routine differs from others’. |