亚洲精品久久久久久一区二区_99re热久久这里只有精品34_久久免费高清视频_一区二区三区不卡在线视频

Beijing's forests have a new biological weapon against insect attack - red-eyed wasps. 

For the first time in China, Xishan Forest Farm in the Chinese capital has used the wasps, also called trichogramma, to kill insects devouring tree leaves, farm official Yan Haiping said yesterday.

 

"Compared with traditional chemical pesticides which kill the pests and the beneficial insects as well, while polluting the environment to a certain degree, red-eyed wasps, known as Chiyan Feng in Chinese, are a better choice," he said.

 

Red-eyed wasps kill more than 200 kinds of pests, including the bug that destroys the famous red leaves of the Fragrant Hills (Xiangshan) in autumn, by laying eggs in the bodies of the insects or of their pupae.

 

According to Yan, the forest farm has released a total of 20 million wasps.

 

However, Yang Hongzhu, director of the Beijing Promotion Center for Bio-measures in the Prevention and Treatment of Forest Insects, denied there is a major pest problem in Beijing's forests, despite the hotter, wetter conditions this year.

 

"Yes, there are insects this year. But the situation is not worse than previous years," he said.

 

"We have tried the wasps this year only as part of our strategy to steadily increase the adoption of bio-measures in preventing and controlling forestry pests."

 

The strategy aims to protect local forests at the least possible cost to the environment, according to Yang.

 

Yang said his center is one of the country's largest production bases for these beneficial insects.

 

The center can breed six varieties of parasitic wasps and two types of viruses to fight forest pests.

 

These special bugs have in the past helped control the pine caterpillars that devastated the city's plantations.

 

Yang believes bio-measures are of great value to the forestry industry. Plantations tend to be dominated by one tree species, leaving them vulnerable to insect attack.

 

"While chemical pesticides tend to be of little use in such cases, bio-measures can quickly get things under control. The pests cannot develop antibodies against natural enemies," Yang said. "That is why more regions are adopting bio-measures to fight against forest pests."

 

(China Daily August 8, 2003)