China releases 600 million wasps to combat moths

(PhysOrg.com) -- Chinese forestry officials have released some 600 million parasitic insects into the north China city of Baoding to combat the spread of the American White Moth that has been (in their caterpillar stage) eating the leaves off of forest and domestic orchard trees, as well as some farm crops. This is the fifth year in a row that Chinese officials have released wasps hoping to reduce the damage caused by the moths.

The American White Moth, known in the U.S. as the Fall Webworm, (though some call them “forest locusts”) creates, during its larval stage, the familiar webbed nests seen on hardwood tree limbs all across the country. It is one of the few insects that have migrated from North America to other parts of the world. The Fall Webworm doesn’t generally harm the trees where it lives, though it does reduce the amount of leaves on them, which isn’t considered all that much of a problem until it moves to orchards where large swarms of them can actually totally denude a tree, leaving it with little means to collect sunlight for converting to energy for growing fruit.

The American White Moth was first seen in China in Liaoning province back in 1979 and has been considered a pest ever since. This year alone, Chinese experts estimate that the moths have infested approximately 20,000 hectares of farmland and forest in and around the city where the insects were released.

Professor Yang Zhongqi, a Chinese entomologist is credited with discovering that wasps, known as "chouionia cunea Yang," could be used as a natural moth control vehicle when he found that a type of bee use their stingers to bore into the moth pupae and kill the larva inside in order to eat them. Zhongqi is also credited with giving the moth’s their Chinese name.

Chinese entomologists breed the wasps on a huge scale employing silkworm cocoons, which they hang on trees in the areas where the moths are known to reproduce. Locals have given them the nickname “forest defenders” because of their ability to effectively control populations of the moths.

In prior years, the wasps have been used to fight moth infestations in other provinces as well, and even in Beijing, and while releasing wasps does seem to be an effective and eco-friendly way to control the pests, experts warn that releasing wasps as a sole means of eradicating the American White Moth, is likely to be insufficient.

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