Controlling Pests

Professor Chris Gilligan, Director of Research in the Department of Plant Sciences, University of Cambridge, has been looking at the problems of controlling pests and diseases which attack crops, particularly in Sub-Saharan Africa. Whilst some of these are familiar, others are new and now appearing for the first time. All of them, however, are major threats to food production and the livelihoods of the farmers who depend on their crops.

These pests and pathogens pose a serious threat in that they ravage boundaries and borders and can sweep across vast swathes of the African continent in weeks, or, in the “right” weather conditions, days. Although some pesticides and fungicides can control and even eradicate these invaders, they are expensive and often not available in the quantities needed at the time when they would be most effective.

Gilligan realised that they needed an “epidemiological toolkit” to account for the varying factors to allow them to predict which diseases are most likely to occur, how they will spread, and how they can best be controlled and halted at a price the farmers can afford.

Having a model which can predict which diseases will affect which crops at what time is one thing, however, unless it can be used to ensure the farmers have the right chemicals in the right quantities at the right time and they know which to use and how to apply it, then the model will be of little more than academic interest.

Currently, Gilligan’s models are being used by governments across the world and they are helping to preserve livelihoods. Some of the applications include forecasting wheat rust in Ethiopia; the cross-continental spread of Cassava brown streak disease (CBSD) and; ash dieback, Ramorum disease (of larch) and Oak processionary moths across UK woodlands.

The early warning system (EWS) using UK Met Office weather forecasts in cooperation with the Ethiopian Agricultural Transformation Agency (EATA) and others, has enabled half a million smallholders in a region of Ethiopia “to take timely action reducing risks to food supplies”. This service has been subsequently implemented across Bangladesh, Nepal, and Kenya.

Around half a billion people across Sub-Saharan Africa rely on Cassava as their staple food crop. CBSD can reduce the yields of Cassava by 50 to 100%. As part of Gilligan’s work, fourteen African countries will soon be working together to control this pest. Oak processionary moths were inadvertently introduced into the London area in 2005 and have been spreading outwards. Gilligan’s team has devised surveillance plans which are starting to show signs of success. Gilligan studied “Agricultural and Forest Sciences” as an undergraduate at Oxford but taught himself statistics and mathematics during his time at Cambridge.