Tiny wasps, Mealybug and Cassava

An army of a quarter million South American tiny wasps (Anagyrus Lopezi), released into Thailand’s mealybug affected cassava crops, began their work on a silent way.

According to Thailand’s Agricultural ministry, the experiment has worked successfully to thwart a pest decimating one of the country’s largest food exports.

Entomologists deployed the first batch over the weekend in a campaign to eradicate a plague of mealybugs that threatens crops in Khon Kaen province in northeastern Thailand.

The mealybugs, a recognized enemy of cassava crops in South America and Africa from three decades ago, have arrived in Asia.

Scientists confirmed the spread of the cassava mealybug to about 200,000 hectares of farmland in eastern and north-eastern Thailand in late 2009.

The wasps, each smaller than a pinhead will be released in pairs, home in on the mealybugs, piercing and laying their eggs inside them. The larvae devour the mealybugs from within, emerging in a few days from their mummified shells to seek new hosts.

The use of wasps, which has been effective in Africa, is expected to also succeed in Thailand, the world’s leading exporter of cassava, which is also known as manioc, tapioca and yucca.

Early signs of mealybug infestation have been reported in Cambodia, Laos and Myanmar, Thailand’s neighbors.

Thailand, the third largest producer of cassava, after Nigeria and Brazil, accounts for 60 percent of worldwide exports of the root, which is used in foods like noodles, the flavor-enhancer monosodium glutamate and products including toothpaste.

The mealybugs, with a life cycle of about a month, can spread quickly, with each insect laying an average of 440 eggs and producing 10 generations in a year. The bugs feed on the tips of cassava plants, stunting their growth with toxic saliva.

The threat to Thailand’s $1.5 billion cassava industry emerged in force last year, when 20 to 25 percent of the crop was destroyed, frightening farmers and driving up prices.