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A possible safe new way to kill mosquitoes that spread malaria

[ 2011-03-01 15:46]     字号 [] [] []  
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A possible safe new way to kill mosquitoes that spread malaria

This is the VOA Special English Health Report.

Israeli researchers say they have developed a substance that attracts and kills mosquitoes infected with the malaria parasite. However, the sweet smelling substance is said to be harmless to people and animals.

Scientists at Hebrew University in Jerusalem developed the sugary bait by combining fruit juice oils and boric acid. The fruit juice gets the attention of the mosquitoes. Boric acid kills the insects when they eat it.

The scientists took the boric acid sweet bait to the West African nation of Mali. They sprayed it on plants near man-made ponds. Villagers use water from the ponds during the dry season. But the area is also home to Anopheles gambiae, the mosquito that carries the most deadly form of malaria.

The researchers also placed a sweet-smelling spray on grasses near other ponds. But that spray contained no boric acid.

Both substances also contained a substance that would mark any mosquito that came in contact with it. This way the scientists could count the mosquitoes that fed on the bait.

Yosef Schlein is an expert on insects that affect human health. Professor Schlein led the sweet bait research. He says 38 days of results show the sweet boric acid bait proved very effective at killing mosquitoes.

YOSEF SCHLEIN: "In Mali, we got down by some 80 percent, the females, and 90 percent of the males. But the area is full of little ponds in there, so it is impossible to stop mosquitoes from flying from an untreated pond to a treated pond."

At the ponds treated only with sweet-smelling bait, Professor Schlein says, more than 75 percent of mosquitoes fed on the false bait. He says most people do not know that female mosquitoes feed on sweet plant nectars to survive. Their blood feedings are part of reproduction.

The Israeli researchers now hope to develop a bait that is even more desirable to the malaria mosquitoes.

Boric acid is generally safe for human beings and other mammals. Professor Schlein says scientists might be able to develop a mosquito bait for enclosed spaces. Boric acid has been used to kill other insects including cockroaches, termites and ants inside homes since the middle of last century.

A report about the malaria mosquito sweet bait was published in Malaria Journal.

And that's the VOA Special English Health Report. You can find this report and more health news at voaspecialenglish.com. You can also follow us on Facebook, Twitter and YouTube. I'm Mario Ritter.

malaria: a disease that leads to fever and shivering caused by the bite of some types of mosquito 疟疾

boric acid: 硼酸

anopheles: a mosquito of a genus that is particularly common in warmer countries and includes the mosquitoes that transmit the malarial parasite to humans 疟蚊

nectar: a sweet liquid that is produced by flowers and collected by bees for making honey 花蜜

cockroach: a large brown insect with wings, that lives in houses, especially where there is dirt 蟑螂

termite: an insect that lives in organized groups, mainly in hot countries. Termites do a lot of damage by eating the wood of trees and buildings. 白蚁

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(来源:VOA 编辑:崔旭燕)