快猫短视频

A CHEAP, eco-friendly alternative to pesticides will soon be tested in Tanzania.

The African army worm (Spodoptera exempta) can reach plague proportions, with over 1000 caterpillars per square metre, and wipe out over 90 per cent of a maize crop. At the moment, the only cost-effective way to control it is to bombard it with pesticides, but these have obvious disadvantages: a 1990 UN report estimated that 11 million farmers in Africa suffer from pesticide poisoning each year.

A more environmentally friendly solution is to use a kind of nucleopolyhedrovirus (NPV) that infects only the army worm. Applied in large quantities, it can start a massive outbreak, devastating the pest. But mass-producing viruses like NPV in the quantities required to tackle army worms costs more than pesticides.

So David Grzywacz at the University of Greenwich in London is instead copying a method used in Brazil to deal with outbreaks of the velvet bean caterpillar that feeds on soya. There, workers watch for outbreaks early in the season, infect the caterpillars with a virus, then collect tonnes of dead, virus-laden caterpillars. The caterpillars can be mashed up and used as a spray to tackle later outbreaks.

This is significant because farmers are already used to spraying. 鈥淭he easier it is to use, the easier it will be to get them to adopt it,鈥� says Grzywacz. He hopes mass production of NPV in Tanzania will enable the virus to be sold to farmers for just a tenth of the price of pesticides.