Thirty-two exotic species are causing damage worth 56 billion yuan to China's forestry industry every year, State Forestry Administration (SFA) vice director Zhu Lieke has said.

Of 292 forestry-threatening species in China, 32 came from abroad and 16 appeared in China in the past 28 years, he said.

On average, serious damage caused by harmful species struck about 10.7 million hectares of forest each year. Although forests damaged by alien species only account for 20 percent of that, they represented 60 percent of the total value, Zhu said.

He was speaking at a forum on biological remedies for exotic species on Friday, which attracted experts and officials from 16 countries and regions.

"To put it in simple terms, biological cures mean you use one bug to kill another," said SFA senior engineer Wu Jian.

The American white moth had been one of the worst pests since it came to China in the late 1970 and spread through Shandong, Liaoning and Hebei provinces, he said.

Every year, China released about five billion Chouioia cunea, a type of bee that was the natural enemy of the moth, Wu said.

"Biological cures have drawbacks. For example, they often take time to be effective," Wu said. "However, they are more environment-friendly than pesticides.

"Frankly, it will take a while for China to employ biological cures nationwide and the cure itself is slow," he said. "But the important thing is China is looking into it."

(Xinhua News Agency September 22, 2007)