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Reducing post-harvest loss in African smallholder farms: An interdisciplinary approach to pest and disease control

Dr Steven Sait (SOB), Dr Martin Dallimer (SEE)

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Post-harvest losses of food produced in developing countries can be more than 30% of total produce (Figure 1). As well as variable and unpredictable weather and inadequate storage, the major contributors to this loss are insect and pathogen infestations. These include the invasive Large Grain Borer (Prostephanus truncatus), Lesser Grain Borer (Rhizopertha dominica), Grain Weevils (Sitophilus spp.) and Flour Beetles (Tribolium castaneum, T. confusum), as well as aflotoxin contamination that can cause serious harm to humans. Where present the Large Grain Borer is causing particularly acute losses compared to native pests. The resulting economic losses exacerbate poverty and food insecurity for smallholder farmers.

Figure 1. Postharvest losses of Maize cross Africa ( Total annual postharvest losses for cereals in Africa occurring along the entire supply chain including harvesting, transport to home, drying, threshing, winnowing, farm storage, transport to market and market storage.

Existing interventions involve the use of chemical pesticides, but these are often too expensive to be used widely and their residues are a major health concern. More sustainable techniques could transform existing interventions. For example, parasitoid wasps can be effective control agents against the invasive larger grain borer (Kfir et al. 2002). A number of pathogens of insect pests, such as bacteria, fungi and viruses, may be able to augment their control in a sustainable way (Cherry et al. 1999).

This would be an exciting interdisciplinary project that combines community ecology of insect-natural enemy interactions, the valuation of ecosystem services and disservices in agricultural landscapes, sustainable agriculture and economic impacts of pests.

As well as the potential to carry out laboratory microcosm research in Leeds, field work would be undertaken in Malawi to examine the main causes of losses to pests and diseases in a range of post-harvest systems and to explore the costs and benefits of interventions in terms of reduced crop losses, farmer livelihoods, local and national food security. The enclosed stores where crops are kept offer an ideal opportunity to undertake controlled experiments in order to understand the community ecology of these multi-species systems and examine the interaction between regional climate, storage micro-climate and loss.

This project would be allied to other research in Malawi and will benefit from existing networks associated with the Environment and Development Group in the School of Earth and Environment, which has a well-established network of collaborators and contacts in Eastern and Southern Africa. Currently Prof Andy Dougill and Dr Pete Steward are investigating the pre-harvest resilience of different types maize to climatic extremes with in collaboration with Lilongwe University of Agriculture & Natural Resources in Malawi (LUANAR) and the Department of Agricultural Research Services (DARS). There are facilities and expertise in post-harvest crop losses at LUANAR and DARS.

The project will be supervised by Dr. Steven Sait, an insect community ecologist with special interests in agro-ecology (e.g. Inclán, D.J. et al. (2015) Organic farming enhances diversity of tachinid parasitoids at multiple spatial scales. Journal of Applied Ecology 52, 1102-1109; Gabriel, D. et al. (2013) Food production vs. biodiversity: comparing organic and conventional agriculture. Journal of Applied Ecology 50, 355-364; Sait, S.M. et al. (2000) Invasion sequence affects predator-prey dynamics in a multi-species interaction. Nature 405, 448-450).

The project would be co-supervised by Dr. Martin Dallimer whose interests are in understanding the valuation of ecosystem services and disservices, sustainable agriculture, economic impacts of pests.

See also:

Cherry, A. et al., (1999) Pathogen incidence & their potential as microbial control agents in IPM of maize stem borers in West Africa. Biocontrol 44, 301-327.

Kfir, R. et al., (2002) Biology and management of economically important lepidopteran cereal stem borers in Africa. Ann. Rev. Entomol. 47, 701-731.

Related undergraduate subjects:

  • Biology
  • Ecology
  • Evolution
  • Zoology