Better way to trick mosquitoes involves attacking smell sense

In many regions of the world, mosquitoes carry serious diseases like malaria and dengue. The World Health Organization estimates that almost 630,000 people died of malaria-related causes in 2012, mostly in Sub-Saharan Africa.  In Costa Rica thousands contract dengue each year and a few die.

Now, a group of U.S.-based scientists is working to develop a more effective and less expensive mosquito repellent than currently in use.

The research at the University of California Riverside is based on the fact that mosquitoes use the same receptor for detecting carbon dioxide in human breath as they do for the odor from skin when they come closer.

The lead investigator, Anandasankar Ray, says scientists tested more than a million chemical compounds until they found a substance called ethyl pyruvate that shuts down the mosquitoes’ receptor.

“When we apply ethyl pyruvate to a human arm and offer it to hungry mosquitoes in a cage, then very few of the mosquitoes are attracted to the human arm because only a few of them are able to smell it out,” said Ray.

Genevieve Tauxe, also on the team, says finding the mosquito neurons that detect both human breath and skin odor was not easy.

“With this apparatus, we are able to insert a very small electrode into the part of the mosquito’s nose, effectively, where its olfactory neurons are and where the smell is happening,” said Ms. Tauxe.

With these instruments, scientists were able to detect the signals that a mosquito’s neurons send to its brain when it senses attractive odors.  Spikes on the computer screen show when the attraction is strong or weak.

Ray says a repellent based on ethyl pyruvate may be cheaper to manufacture than DEET, the most effective chemical now in use. He says DEET is too expensive for most people in malaria-affected areas.

“Perhaps by finding designer odors, better odors that can attack other target receptors, we will be able to improve upon DEET and finally have the next generation of insect behavior control product,” he said.

The University of California scientists say they believe they will soon be able to find a way to manufacture cheaper and more effective repellents for the fight against mosquitoes.

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