Modelling and manipulation of plant-aphid interactions: A new avenue for sustainable disease management of an important crop in Africa

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Project start: 1 November 2012

Project end: 30 June 2016

Beans are a vital crop in eastern and central Africa, both as an essential part of the diet, rich in protein and micronutrients such as iron, and as a natural fertilizer, enriching the soil with fixed-nitrogen. However, aphid-transmitted viruses pose a serious risk to beans, resulting in large losses for smallholder farmers.

The aphid-transmitted bean viruses, bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV), cause huge yield losses for smallholder farmers in Africa. While beans have been historically bred for resistance to BCMV, the occurrence of BCMNV in Africa has turned these “resistant” varieties into plants that overreact to the virus, causing black root disease with up to 100% yield loss.

The project

Previous work by researchers from the University of Cambridge has demonstrated that virus infection alters the biochemistry of plants to make them smell and taste different to insects, including aphids, which results in insects spreading the virus further. The team surveyed bean growing areas in different ecological zones within Kenya and Uganda to gain an understanding of how virus infection in the plants shapes the distribution of aphids under natural conditions. In addition, the team used a combination of molecular analyses, mathematical models and field observations to identify how to select and deploy plants that could act as decoys for aphids by attracting them.

Findings

The project found that virus particles of BCMV and BCMNV are acquired from infected plants and lost rapidly in uninfected hosts when the aphids feed. Thus, transmission is favored when aphids settle very briefly on an infected plant before moving on to an uninfected plant. The understanding of vector-virus-plant interactions will be used to design epidemiological models based on the push-pull pattern to inhibit virus transmission.

Project partners

  • BecA-ILRI Hub
  • The University of Cambridge
  • Rothamsted Research
  • The Eastern and Central African Bean Research Network (ECABREN) coordinated by the International Center for Tropical Agriculture (CIAT) Uganda

 

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