They find chemical compound that attracts Zika and dengue mosquitoes

A team led by the University of California Riverside (USA) The combination of carbon dioxide plus two chemicals, 2-ketoglutaric and lactic acids, causes a characteristic odour. This causes the mosquitoes to find their victim and land on it. This chemical cocktail also encourages skin picking using piercing mouthparts to find blood.

This chemical mixture appears to attract female mosquitoes in particular. aedes aegyptiZika vectors as well as chikungunya, dengue and yellow fever viruses. This mosquito originated in Africa but has spread to tropical and subtropical regions around the world, including the United States.

This discovery was published in the journal Scientific Reports. “While others have identified compounds that attract mosquitoes, many do not have a strong and immediate effect. This is it,” said Ring Cardé, an entomologist at UCR.

Smell is more important than other factors

Mosquitoes use various cues such as carbon dioxide, vision, temperature and humidity to locate their victims. However, Cardé’s latest research shows that skin odors are even more important than previously thought for mosquitoes to identify human victims.

“We showed that mosquitoes land on visually ambiguous targets filled with these two scents, and these targets are not associated with heat or humidity,” says Cardé. “This leaves skin odor as the main driving factor.”it was stress.

Given the importance of scent in helping mosquitoes bite humans successfully, Cardé wanted to explore exactly the chemicals that make our scent so powerful for insects. Part of the equation, lactic acid was identified as a chemical element in the fragrance cocktail as early as 1968.

Since then, several studies have determined that carbon dioxide combined with ammonia and other chemicals produced by humans also attracts mosquitoes. However, Cardé, who has been working on these insects for 26 years, these other chemicals were not strong enough attractants.

“I suspected there was something to discover about the chemistry of scents that attract yellow fever mosquitoes,” Cardé said. “I wanted to detect the exact mix.”

The methods that chemists typically use to identify these products won’t work for 2-ketoglutaric acid, the scientist noted. Gas chromatography, which separates chemicals by molecular weight and polarity, would also have missed this acid.

“I believe it These chemicals may not have been found before due to the complexity of the human odor profile. and Jan Bello, a chemist who is now a former UCR member with the insect pest control company Provivi.

Seeking mosquito attractants, Cardé turned to Bello, who extracts compounds from the sweat of her own feet. She stuffed her socks with glass beads and spent four hours walking around with the beads inside her socks to collect the scents.

The inconvenience caused by this strange experience was well worth it. Bello isolated the chemicals from the sweat accumulated in the glass beads in the socks and observed the mosquitoes’ response to these chemicals. This is how the most active combination turned out: 2-ketoglutaric and lactic acids.

Now the researchers plan to conduct further studies to determine whether the same compound is effective for any other mosquito.and why the odds of individuals being stung are so diverse. “Some are more attractive to these mosquitoes than others, but no one has yet determined why this is so,” Cardé said.

While this discovery did not lead to ideas for the development of new repellents, the research team hopes that their discovery could be used to attract, trap and potentially kill disease-spreading mosquitoes.

“We were very happy to find these compounds, because we weren’t always sure we would find them. We felt they were there, but emotions don’t always work,” Cardé said.

Reference work: https://www.nature.com/articles/s41598-022-19254-w

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