Knowledge for a sustainable world

David Grzywacz, Philip C Stevenson, Steven Belmain

Central to the issues of high levels of poverty in sub-Saharan Africa is low agricultural productivity. David Grzywacz, Steve Belmain and Phil Stevenson of NRI co-authored a paper just published in the journal 'Food Security', which explores how indigenous ecological resources could be of value in promoting better pest control as a means of reducing losses.

Food crop harvests suffer at least 30% losses due to pests in Africa and managing this will help to secure food and boost economic growth. However, synthetic agrochemical pesticides have had only a limited impact on the productivity of smallholder farmers, many of whom are not able to afford or access these imported chemicals, which have limited availability.

One solution, Grzywacz et al. argue, is to harness biological resources that are locally available, such as the natural enemies and diseases of insect pests and using indigenous plant materials that have pesticidal qualities.

Two examples of natural pesticide measures already being used in Africa and discussed in the paper, are Tephrosia vogelii, a wide ranging pesticidal plant species, and the local harvesting and use of a natural insect pest disease of the African armyworm, the Spodoptera exempta nucleopolyhedrovirus (SpexNPV).

Both of these can be produced locally and have shown promise in trials as inexpensive and effective tools for pest control in sub-Saharan Africa. Their use is currently being scaled up and evaluated by African research networks.

While both systems show promise, the paper also highlights and suggests solutions to the very significant challenges that would need to be overcome in developing production, supply and marketing systems that are economically viable and sustainable.