Collaborative research study between Lancaster University, University of Greenwich and Tanzania (EcoAgriConsult Ltd.) find new biopesticide to control armyworms and other insect crop pests around the globe.
Wolbachia are common vertically transmitted endosymbiotic bacteria found in < 70% of insect species. This intra-cellular bacterium has taken centre-stage recently because researchers discovered that when some insects, including mosquitoes, carry Wolbachia it protects them from viruses including the virus which causes the devastating human disease called dengue. Wolbachia-carrying mosquitoes have been released in northern Australia in an attempt to get the bacterium to spread through the local mosquito population so as to reduce dengue transmission in the area. This finding inspired the researchers on Lancaster University that on contrast to the mosquito results they proof that Wolbachia in a major African crop pest increases susceptibility to viral disease rather than protects.
The researchers provide data from field populations of a major crop pest, African armyworm (Spodoptera exempta), which show that the prevalence and intensity of infection with a nucleopolydrovirus (SpexNPV) is positively associated with infection with three strains of Wolbachia. SpexNPV - a baculovirus that naturally infects and kills the African armyworm - is ideal for use as a biopesticide in Africa because not only can it be produced cheaply and locally, but it only infects armyworm caterpillars, leaving beneficial insects, livestock and humans completely unharmed. Researchers also use laboratory bioassays to demonstrate that infection with one of these strains, a male-killer, increases host mortality due to SpexNPV by 6–14 times These findings suggest that rather than protecting their lepidopteran host from viral infection, Wolbachia instead make them more susceptible. African armyworm are a major threat to global food security, especially in Africa and other parts of the developing world where chemical pesticides are too expensive for most resource-poor farmers. This new strategy could multiply the effectiveness of this biopesticide for the biological control of other insect crop pests.
If you would like to read more about this 3 year research project funded by the Sustainable Agriculture Research for International Development programme - a joint initiative by the UK’s Department for International Development and the BBRSC please follow this link to the Lancaster University News and find therein the link to research article published on Ecology Letters.