More biological measures will be taken to protect the country's forests from attack by alien invasive species, a senior forestry official said yesterday.

Zhu Lieke, deputy director of the State Forestry Administration (SFA), was speaking at a three-day international conference on the subject that opened on Friday in Beijing.

Biological control is recognized internationally as a good way to deal with pernicious pests and plants, as it employs ecological tactics such as the use of natural enemies and does not pollute the environment.

"China has strengthened its biological control efforts in recent years," Zhu said. "This has helped the country not only protect its forests, but also help secure the global ecology."

He gave the successful example of how an infestation of fall webworm was dealt with by cultivating its natural enemy, Chouioia cunea (a type of wasp).

Fall webworm (a species native to North America, also known as the American white moth), could pose a threat to Beijing's vision for a Green Olympics, as it has spread to the capital and surrounding areas in recent years, Zhu said.

It was first spotted in Beijing, Tianjin Municipality and Hebei Province in 2005.

A family of moth larvae can strip the leaves off a healthy tree in just a few days, he said.

An investigation by the SFA showed that in 2005, 156,000 hectares of trees were stricken by the moths. A year later, the pests had spread to an additional 67,000 hectares. The SFA said the moths are expected to devour a further 47,000 hectares of trees in Beijing and its adjacent regions this year.

But the preventative measures, including biological control, already adopted might prevent a serious outbreak in Beijing from happening, Zhu said.

"China is one of the countries that suffers most from invasions by alien species. It has brought security concerns for the country's ecology, species, fresh water, energy, grain, timber and climate," he said.

SFA figures show there are currently 32 alien invasive species in the country's forests, 16 of which have entered China in the past 28 years. These include the fall webworm, red turpentine beetle, pine wood nematode, coconut leaf beetle and emerald ash borer.

The SFA said the cost of the damage caused by the alien species is more than 56 billion yuan ($7.5 billion) a year.

(Xinhua News Agency September 22, 2007)