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Biopesticide to become more lethal against African crop pest

An unexpected discovery could make Tanzanias microbial biopesticide, SpexNPV, up to 14 times more effective against the African armyworm

Researchers from EcoAgriConsult Limited (Tanzania) and universities of Lancaster and Greenwich, have been working on a new strategy to control the African armyworm and other insect crop pests.

The team discovered that infection with a particular strain of Wolbachia, an intra-cellular bacterium, made mosquitoes more susceptible to viral infections carried by them and had the same effect on African armyworms.

"The African armyworm population carrying lots of Wolbachia also have much higher viral loads and more of these caterpillars die naturally of viral disease," said Lancaster Environment Centre project leader Professor Ken Wilson.

The biopesticide, which could be produced cheaply and locally, is a baculovirus that naturally infects and kills the African armyworm said. It leaves the beneficial insects, livestock and humans completely unharmed, the researchers said.

The African armyworm, a caterpillar pest with a voracious appetite, feeds on cereal crops such as maize, wheat, millet and rice, sometimes resulting in total crop loss. Its density could go up to 50,000 caterpillars per hectare.

University of Greenwich researcher David Grzywacz, a co-author of Ecology Letters which has published the findings, said "Adult armyworm moths are highly migratory and disperse over vast areas of sub-Saharan Africa, so it will be a challenge to learn how best to exploit these novel findings for better control of African armyworm."

The Lancaster-led research team however has been optimistic that if similar results are replicated in other crop pests, the mass-release of Wolbachia-infected insects might turn out to be an important weapon to control pests that threaten the African continent's food security.