Darwin Initiative Students conducting biodiversity surveys in bean field fallows
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Harnessing agricultural ecosystem biodiversity for bean production and food security

Evaluating the biodiversity of field margins, to increase their potential to support key pollinators and natural enemies of pests for bean farmers in Africa.

Project details

Project Leader: 
Funded By: 
Darwin Initiative (Defra)

Objectives and outputs

Tanzania’s national poverty reduction strategy paper highlights that food poverty exceeds 18% and agriculture is central to reducing this to 11%. The step-change production increases required to achieve poverty reduction, while ambitious, are realistic, since yields of key crops such as beans (providing protein, micronutrients and vitamins in Tanzania and Malawi) are presently very low (500-700 kg/ha). Consequently, millions of farmers, particularly women (the primary bean growers in Malawi and Tanzania and their households) are at risk of nutritional deficiency and food insecurity. Potential yields are more than 3000 kg/ha but insects and the plant diseases they carry are the major biological constraint for beans. Pesticides can control insects but are rarely used for reasons of economics and availability. 

Biodiversity underpins agricultural ecosystem services and ultimately food security, livelihoods and economic development by augmenting natural enemies, reducing pest impacts and increasing pollination; bean yields can be as much as 40% lower without pollination. Biodiversity in smallholder ecosystems, however, is overlooked in Tanzania and Malawi. Proposed biodiversity evaluations will identify plant species that support key beneficial invertebrates and enhance ecosystem service and resilience, enabling farmers to grow beneficial plants within their cropping systems to improve food security and alleviate poverty.

Kew’s role in the project

The project is directed by Kew Science, building upon current collaborations with Nelson Mandela African Institute of Science and Technology (NMAIST) and Natural Resources Institute, University of Greenwich. Phil Stevenson, Project Leader, has 20 years of experience developing environmentally benign technologies for improved food security in rural communities in sub-Saharan Africa. This work focuses on sustainable use of plants and tackles challenges relating to poverty alleviation. Kew will contribute technically to project activities, while also managing and providing leadership. Specifically, Kew provides the technical expertise in plant sciences to the project. Kew is leading plant diversity surveys of bean agricultural ecosystems and training. Iain Darbyshire has travelled to Arusha in Northern Tanzania twice to train NMAIST postgraduate students and initiate the surveys and project implementation. Kew will also evaluate biological activities of pesticidal plants such as Tithonia diversifolia and Bidens pilosa against field and storage pests of beans.

In summary, Kew will:

  • Oversee the technical and financial management of the project.
  • Ensure all activities are carried out to time and budget.
  • Chair six-monthly project steering group meetings.
  • Implement the communication strategy for project outputs.
  • Co-supervise two McKnight Foundation co-funded PhD students.
  • Lead M&E with a Tanzanian based socio-economic consultant.


  • Raise awareness among farmers and government about how biodiversity underpins food security and how it can be conserved sustainably to improve bean production.
  • Incentivize maintenance and enhancement of ecosystem biodiversity supporting biorational pest management nationally and regionally.
  • Improve bean yield and quality and ultimately food security, through enhanced biodiversity, and promoting sustainable use of pesticidal plant species.
  • Develop sustainable landscape management interventions, ensuring conservation of the biodiversity that underpins food security and rural wealth.


  • Output 1: Ecosystems and plant species that are habitats for key natural enemies of bean pests identified.
  • Output 2: Key invertebrate pollinators of beans and their key habitat (plants/ecosystems) established at 25 locations in four agro-ecological zones.
  • Output 3: Capacity of 400 lead farmers increased by information and guidance on exploiting and maintaining agricultural biodiversity for improved crop yield.
  • Output 4: Field margin plant species that support beneficial insects evaluated for their biological activity against pest insect species of beans and negative effects on natural enemies and pollinators determined.
  • Output 5: Postgraduates trained in conducting biodiversity surveys and carrying out field and laboratory based research.

Partners and collaborators



Further information

Abate et al. (2012). Tropical Grain Legumes in Africa and South Asia: Knowledge and Opportunities. PO Box 39063, Nairobi, Kenya: International Crops Research Institute for the Semi- Arid Tropics. 112 pp.

Bartomeus et al. (2014). Contribution of insect pollinators to crop yield and quality varies with agricultural intensification. PeerJ 2:e328

Belmain et al. (2013). Managing legume pests in sub‐Saharan Africa: Challenges and prospects for improving food security and nutrition through agroecological intensification. Chatham Maritime (United Kingdom): Natural Resources Institute, University of Greenwich. 34p

Gurr et al. (2004). Ecological Engineering for Pest Management. CSIRO, Australia.

Stevenson et al. (2014). Pesticidal plants for stored product pest in small holder farming in Africa. In: Advances in Plant Biopesticides,  ed. D. Singh. Springer Verlag. pp 159

United Republic of Tanzania. NATIONAL STRATEGY FOR GROWTH AND REDUCTION OF POVERTY II. Available as a pdf


Mkenda, P., Mwanauta, R., Stevenson, P.C., Ndakidemi, P., Mtei, K. & Belmain, S.R. (2015). Field margin weeds provide economically viable and environmentally benign pest control compared to synthetic pesticides. PLoS One 10 (11): e0143530

Bartomeus, I., Potts, S.G., Steffan-Dewenter, I., Vaissière, B.E., Woyciechowski, M., Krewenka, K.M., Tscheulin, T., Roberts, S.P.M., Szentgyörgyi, H. & Bommarco, R. (2014). Contribution of insect pollinators to crop yield and quality varies with agricultural intensification. PeerJ 2:e328. Available online 

Amoabeng, B.W., Gurr, G.M., Gitau, C.W., Nicol, H.I., Munyakazi, L. & Stevenson, P. C. (2013). Tri-trophic insecticidal effects of African plants against cabbage pests. PLoS One 8(10): e78651.  doi:10.1371/journal.pone.0078651.

Grzywacz, D., Stevenson, P.C., Belmain, S.R. & Wilson, K. (2014). The use of indigenous ecological resources for pest control in Africa. Food Security 6: 71–86.