China is considering stricter control over imports of exotic species of plants and animals, many of which have already damaged its environment.
"Last year less than three days after my family and I had transplanted seedlings of late rice in our 0.07-ha field, the seedlings were eaten up by Fushou snails scattered across the field," complained a farmer surnamed Liu from Pingle County in Guilin City, Guangxi Zhuang Autonomous Region.
The species of snail Liu mentioned, Amazonian snail which is dubbed "Fushou snail" in China, was introduced to the southern county in the 1980s as a food delicacy. However, the snails bred very rapidly to infiltrate all lakes, brooks and ponds in the whole county - a disaster for local farmers as they tended to eat every seedling in the rice fields and seize bait from carp in fishponds.
Making matters worse, the Amazonian snail is strongly resistant to highly toxic pesticides. Farmers have to pick them up by hand and take them far from water so they shrivel to death or directly bury them. But such labor-intensive methods have proved ineffectual against the powerful potency of the river snails. Having run out of options, the farmers are appealing to scientists to find or breed a natural enemy of the river snail.
The Amazonian snail disaster has not only occurred in Pingle County but has also spread into Guilin and even Guangxi at large, according to the municipal Agriculture Bureau at Guilin.
As for other exotic species causing ecological damage in China,a more striking example is the hyacinth, imported in 1901 as an ornamental plant and popularized as pig fodder in the 1950s-1960s.
Owing to its rapid propagation, the hyacinth, listed among the world's top 10 most harmful plants, polluted Dianchi Lake, a well-known tourist destination in southwest China's Yunnan Province.
The lake, however, is not the only hyacinth victim. The plant has plagued the river system in Shanghai, the largest metropolis in east China, the Dongting Lake system in central China and the whole Pearl River system in south China's Guangdong Province, an economic powerhouse of the nation.
"There were some 1.84 million tons of hyacinth in Shanghai's Huangpu River system in the January-August period, " said Wei Jumin, an urban environmental official. "So far, we have had nearly 600,000 tons of it dredged up."
According to Guangdong's provincial Administration of Environmental Protection, from 1975 till now, hyacinth in the Pearl River system multiplied by 10 times every 10 years. In 1975,about 5,000 tons of hyacinth were dredged up per day from the river system; one decade later the figure went up to five tons, and now, the amount is as high as 500 tons.
The invasion of several major alien flora and fauna species in China causes average annual economic losses worth 57.4 billion yuan (6.9 billion US dollars), official statistics show.
Wang Dehui, deputy director of the Nature and Biology Conservation Department of the State Environmental Protection Administration, said it was a huge mission to protect native species from alien destroyers.
Such species had become one of the major factors endangering China's biodiversity and the biological environment, he said.
To tackle the problem, specialists from the State Administration of Environmental Protection and the Chinese Academyof Forestry Science are calling for sensible measures and stricter control over imports of exotic species. They suggest that laws and regulations concerning such imports should be introduced as soon as possible and awareness of invasive species should be raised among the public, particularly among government officials and scientists.