Natural Pest Regulation on Orphan Crop Legumes in Africa (NaPROCLA)

Population growth and associated rising food demands places increasing pressure on global food production, and by 2050 the world will need 60% more food than is available today with pressure on limited land area to produce adequate food sustainably while reducing chemical inputs. Severe pest damage of crops is one of the major challenges to food and nutritional security and disproportionately affects poor farmers and low-input orphan crop grain legumes such as beans, pigeon pea, cowpea and lablab. Pest control is often overlooked on orphan crop legumes, but any management of the pests is dependent on high agrochemical inputs which have negative impacts from exposure of users and consumers and where pesticides severely impact non-target invertebrates that can be beneficial to food production through pollination or natural pest regulation. Agricultural systems are ecologically complex and must function with natural habitats rather than deplete them. More resilient agriculture and focussed investments for smallholder farmers can deliver transformative change and enhance prospects and livelihoods of the world's poorest while safeguarding against future risks.

In Tanzania, Kenya and Malawi, legumes are grown and consumed by millions of farmers and their families providing protein, micronutrients and vitamins so represent one of the most important means to enhance nutritional security. East African poverty reduction strategy papers highlight that food poverty exceeds 18% in these countries and agriculture is central to reducing this livelihood gap. Yields of key legumes such as beans and cowpea are presently very low (500-700 kg/ha) but potential yields are >3000 kg/ha. Consequently, millions of farmers, particularly women (the primary growers of orphan legume crops in Kenya, Malawi and Tanzania), and their households have great potential to increase nutritional and food insecurity by improving production of legumes.

Biodiversity underpins agricultural ecosystem services and food security, livelihoods and economic development by provisioning natural enemies of crop pests. Natural enemies reduce populations of pest insects thereby reducing reliance on synthetic insecticide application. Through this saving their contribution in the US alone is reported to be $13.6 billion annually so the benefits of natural pest regulation can be measured in environmental and economic terms. Non-crop habitats such as field margins provide the environment with diverse food resources required to support arthropod predators and parasitoids. Management or manipulation of this non-crop habitat can help to support natural pest regulation and can even be augmented and sustained in better managed natural or manipulated agro-ecosystems. The occurrence, density and impacts of most beneficial insects in smallholder ecosystems, however, are poorly understood, particularly in Africa.

The research proposed here will take forward recent findings by our partnership and identify the key taxa that support and deliver natural pest regulation. We will develop approaches that support and augment natural pest regulation through improved agroecosystems management with reduced pesticide use. The proposed research will provide key evidence for benefits of natural pest regulation and establish how this can be optimised through better landscape management or manipulation and how natural pest regulation can function alongside other management practises including natural pest resistance, botanical insecticides and intercropping.

Natural pest regulation provided by wild invertebrates in agriculture is dependent on flowering plants in field margins because these plants provide food as nectar or pollen or alternative insect hosts. There is surprisingly little information on the role of natural enemies in controlling pests on orphan legume species. We will evaluate how the diversity of beneficial insects for orphan crop legumes in East Africa (beans, cowpea, pigeon pea and lablab) is influenced by different management strategies (natural and biodiverse field margins, or engineered with key plant taxa). By manipulating field margins and implementing field trials of single and combined pest management strategies, we will build an evidence base for optimisation of natural pest regulation services. We will evaluate how they can integrate with other pest management approaches including host plant resistance and application of botanical insecticides.
Using field, station and laboratory experiments we will:
1. Identify the key natural enemy taxa specifically to black bean aphids (Aphis fabae) and legume pod borer (Maruca vitrata) using field surveys, cage trials and metabarcoding.
2. Evaluate impact of field margin management on abundance and diversity of natural enemies of the black bean aphid and legume pod borer and measure relationships between beneficial insect populations and crop damage/yield.
3. Map relationships between natural enemies and wild plants.
4. Evaluate the impact of integrating ecological engineering for natural enemies with other environmentally benign pest management (resistance/plant based pesticides) and yield boosting (e.g., inter-cropping legumes) management practices.
Evaluate whether these approaches differ in their efficacy when implemented in plant diverse versus depauperate landscapes.

The project outcomes will benefit smallholder farmers in sub-Saharan Africa growing orphan crop legumes, extension services, policy makers and scientists worldwide, and ultimately the wider public. Specifically, smallholder farmers in East Africa will benefit from i) a greater understanding of the value of agricultural ecosystems and knowledge about why reducing reliance on chemical inputs can benefit their farming system through lower impacts on beneficial insects; ii) novel and low-input low-cost approaches to manage pests sustainably; iii) greater nutritional and food security and iv) higher quality food products that will be healthier for consumers and potentially of higher market value. Extension services including government and non-government organisations will benefit from new and locally relevant knowledge that will inform extension and outreach programmes to better support farmers to grow food sustainably and reliably. Through training programmes and training tools we will provide extension services with all the information they require to disseminate information and evidence about the value of field margins for sustainable food security. We will engage with policy makers to ensure that they participate and are informed of progress from the project outset. We will provide the evidence and robust data required to be able to make informed decisions about government support for and investment in extension that supports sustainable intensification of agriculture by augmenting and managing agricultural ecosystems to deliver natural pest regulation. Through current interactions including engagement with IPBES and Defra's National Pollinator Strategy under PASG, NRI has experience producing publications tailored to impact policy at the international level: Gill et al. (2015) Adv Ecol Res, Vanbergen et al. (2013) Frontiers in Ecology and the Environment. NRI produces a regular newsletter, the Resource, with global subscription from a range of academic, NGO and governmental sectors, disseminating details about the ongoing research work. NRI has a member of staff permanently seconded to the office of the APPG for Agriculture and Food for Development, allowing greater access to policymakers. The scientific community will benefit from the agricultural innovations and research outputs from this project that will include new information about ecosystem services of wider relevance to the field. All NRI project staff regularly attend and speak at conferences, and give invited lectures at other institutions; we will use these opportunities to share findings from this project with interested parties. The public will learn about the work on this project through outreach events both in the UK and in East Africa including through agricultural fairs. NRI staff regularly engage with the public in a variety of contexts as do our partners in East Africa to help improve awareness among farmers and the wider UK and African public about the importance of beneficial insects in sustainable food production and the global nature of food production and the importance of environmental issues regardless of origin. Project team members will inspire and influence young people through various outreach vehicles including the Inspiring the Future and Future First schemes connecting STEMM and business professionals with young people, and will speak to students in local schools about the results of this project and their importance as part of wider events to increase students' understanding of science careers. Research students at NRI and at our partner institutes will benefit from research-led teaching, including use of case studies in their course delivery. Findings from this project will serve as engaging examples for courses such as Integrated Pest Management and Ecology and Ecosystems. More sustainable management of farms in eastern Africa will support improved biodiversity in human influenced landscapes making agriculture more sustainable.