The tiny parasitic wasp that saved an industry

Scattered among the highly biodiverse forests of South East Asia, millions of farmers eke out their livelihoods by growing cassava. This cash crop – grown by both small-scale farmers who own just one or two hectares and industrial farms spread across thousands of hectares – is sold mainly to manufacturers who use its starch in plastics and glues.

When cassava was first imported to South East Asia from South America (as it was to Africa a few decades earlier), it was able to grow without the help of pesticides. Then in 2008, the cassava mealybug followed the root vegetable to the region and began devastating the crops. To compensate for the losses, farmers began encroaching into the forests around their plots to try to get a little bit more produce from their land.

“Some of those areas are under significant pressure from deforestation,” says Kris Wyckhuys, an expert in biological controls at China Academy of Agricultural Sciences’ Institute of Plant Protection in Beijing. “Cambodia has some of the highest rates of tropical deforestation.”

The arrival of the cassava mealybug not only had major impacts on the livelihoods of those who grow cassava, it affected the national economies of the countries in the region and might have had rippling effects elsewhere.

Substitute products in the starch market like corn and potato rose in price. There was a threefold increase in the price of cassava starch in Thailand – the world's number one exporter of cassava starch.