At least 1,200 tons of insecticide, 50,000 spraying machines and four crop-dusting aircraft have been mobilized to control locusts swarming over an estimated 800,000 hectares across northern China, the Ministry of Agriculture said yesterday.

Ministry official Zhu Enlin said that biological pesticides account for 10 percent of the total being sprayed in nine provinces and municipalities this year in the belief that they will have less of a negative impact on the environment.

Funds earmarked for efforts total 12 million yuan (US$1.4 million), said Zhu, adding "Migratory locusts are not occurring as massively as they did last year and may not pose great harm to crops."

However, efforts to control them are necessary to prevent swarms continuing into the autumn, even though the current insect population is not itself a threat, he added.

According to experts, the locusts' usual habitat is dry wasteland near rivers, lakes and reservoirs, but if their population density is too high they migrate to open land in search of food.

Their density is 5-20 per square meter at present, compared with thousands per square meter last year, according to the Ministry of Agriculture.

The comparatively light density this year is largely a result of last year's effective control measures and heavier rainfall earlier this year, said Zhu.

In an interview yesterday, Lei Zhongren, a Chinese Academy of Agricultural Sciences researcher, said migratory locusts and grasshoppers, cause losses of 60 to 100 million kilograms of grain each year.

Lei said biological pesticides using the fungus Metarhizium flavoviride are increasingly being used as they target the locusts without damaging other species or affecting the overall food chain, unlike chemical pesticides.

(China Daily June 28, 2005)