[ti:California Scientits Find New Substances to Fight Mosquitoes] [ar:Chirstopher Cruise] [al:Health Report] [by:www.51voa.com] [00:00.00]From VOA Learning English, [00:02.56]this is the Health Report. [00:05.27]The sound of a mosquito can mean trouble [00:08.57]in many parts of the world. [00:11.32]The bite of the mosquito can be deadly. [00:15.18]The insects carry serious diseases like malaria. [00:20.53]The World Health Organization estimates [00:24.74]that almost 630,000 people died from malaria [00:30.09]and malaria-related causes in 2012, [00:34.20]most of these cases were in African countries [00:38.30]south of the Saharan desert. [00:41.36]In the United States, [00:43.77]scientists are seeking new ways to fight malaria. [00:49.13]A group of California scientists is working [00:53.48]to develop a more effective and less costly substances [00:58.89]to protect people from mosquito. [01:02.35]The researchers work at the University of California Riverside. [01:07.86]They are investigating the sense of smell in mosquitoes. [01:13.01]They found the insects use the same receptor [01:18.22]for identifying carbon dioxide in human breath [01:22.37]as they do for the smell of our skin. [01:26.27]Anandasankar Ray is leading the investigation. [01:30.98]He says scientists tested more than a million chemical compounds [01:36.84]until they found a substance called Ethyl pyruvate. [01:41.35]He says Ethyl pyruvate makes the mosquitoes' receptor inactive. [01:47.27]"When we apply Ethyl pyruvate to a human arm [01:52.18]and offer it to hungry mosquitoes in a cage, [01:56.23]then very few of the mosquitoes are attracted to the human arm [02:01.79]because only a few of them are able to smell it out," said Ray. [02:05.21]Genevieve Tauxe is a member of the UC Riverside research team. [02:10.86]She says it was not easy to find the neurons of noble cells [02:17.41]that recognise both the smell of human breath and skin. [02:22.77]She describes a device the researchers [02:26.13]are using to examine mosquitoes. [02:29.57]"With this apparatus, [02:31.02]we are able to insert a very small electrode [02:33.52]into the part of the mosquito's nose, [02:36.43]effectively, where its olfactory neurons are [02:39.50]and where the smell is happening," said Tauxe. [02:41.01]The scientists use these instruments to look for the signals [02:45.41]that a mosquito's neurons send to its brain [02:49.37]when it finds an interesting smell. [02:52.64]Computer screen images show when the sense is strong or weak. [02:58.26]Anandasankar Ray says a product based on Ethyl pyruvate [03:03.46]may cost less to manufacture than DEET, [03:07.52]the most effective chemical treatment now in use. [03:11.33]He says DEET is too costly for most people [03:15.77]who live in areas affected by malaria. [03:19.38]"Perhaps by finding odors that can attack other target receptors, [03:26.90]we will be able to improve upon DEET [03:29.51]and finally have the next generation [03:32.06]of insect behavior control products," said Ray. [03:34.61]The scientists believe they will soon be able [03:39.13]to find a way to manufacture less costly [03:42.44]and more effective products for the fight against mosquitoes. [03:47.90]And that's the Health Report from VOA Learning English. [03:53.52]I'm Chirstopher Cruise. [03:55.26]¸ü¶àÌýÁ¦Çë·ÃÎÊ51voa.com