A substance that reduces rat populations by making the males sterile obtained a patent from the state intellectual property right protection authority, reported Dongfang Daily on December 17.
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The new product was developed by Ye Wenhu, a standing committee member of the Genetics Society of China and part-time professor at Fudan University in Shanghai. Its main ingredient is a woody vine, tripterygium wilfordii, used in traditional Chinese medicine.
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The product is fragrant and attractive to rats and, after eating it, the males will gradually produce less sperm until finally becoming sterile.
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Ye said that this is the most economical way to fight rats, and poses no harm to humans.
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Experiments at a designated farm have yielded good results. Tests in 47,000 households and 5,600 work units in Huangpu District of Shanghai reduced the density of rats by 30 percent in three months and by 88 percent half a year later.
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The product has been approved for sale in Australia and some other countries, including Vietnam, Canada, India and the US, have also placed orders for purchase.
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Rats are not only harmful to forests, grassland and food storage, but also spread disease. Rats eat 25 billion kg of grain in China annually, equivalent to 100 million people's consumption.

(Xinhua News Agency December 20, 2004)