Scientists create new way to predict where locusts will next destroy crops

Weather data and state-of the-art computational models have enabled researchers at the University of Cambridge in England to discover a new method to predict where swarms of locusts will strike next, so they can be dealt with before the problem gets out of hand.

Desert locusts typically lead solitary lives until extreme forms of weather – such as intense rainfall – prompts them to swarm in vast numbers, often with devastating consequences.

The migratory pest can reach plague proportions and a swarm covering 1 sq km can consume enough food in only a day to feed 35,000 people. This extensive crop destruction pushes up food prices and can lead to riots and mass starvation.

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This new model predicts where swarms will go as they search for new feeding and breeding grounds. It takes into account the insects’ life cycle and can forecast locust swarm movements short and long term. The areas likely to be affected can then be sprayed with pesticides.

'Hit and miss'

Until now, predicting and controlling locust swarms has been ‘hit and miss’, the researchers said. The model, published on Thursday in the journal PLOS Computational Biology, will enable a quick response to a developing threat.

Desert locust control is a top priority for food security as it is the biggest migratory pest for smallholder farmers in many regions of Africa and Asia, capable of long-distance travel across national boundaries.

Climate change is expected to drive more frequent desert locust swarms, by causing trigger events such as cyclones and intense rain. These bring moisture to desert regions that allows plants to thrive, providing food for locusts that prompts breeding.

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“During a desert locust outbreak we can now predict where swarms will go several days in advance, so we can control them at particular sites,” said Dr Renata Retkute, researcher in the University of Cambridge’s department of plant sciences and first author of the paper. "And if they’re not controlled at those sites, we can predict where they’ll go next so preparations can be made there."

Prof Chris Gilligan, of the same department and senior author of the paper, added: “The important thing is to respond quickly if there’s likely to be a big locust upsurge before it causes a major crop loss. Huge swarms can lead to really desperate situations where people could starve.

“Our model will allow us to hit the ground running in future, rather than starting from scratch as has historically been the case."

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Kenya to India

The team noticed the need for a comprehensive model of desert locust behaviour during the response to a an upsurge over 2019-2021, which extended from Kenya to India and put huge strain on wheat production in these regions. Infestations destroyed sugar cane, sorghum, maize and root crops. The researchers say the scientific response was hampered by the need to gather and integrate information from disparate sources.

“The response to the last locust upsurge was very ad hoc and less efficient than it could have been,” said Dr Retkute. "We’ve created a comprehensive model that can be used next time to control this devastating pest."

The new model will inform surveillance, early warning, and management of desert locust swarms by national governments and international organisations such as the UN's Food and Agriculture Organisation.

The researchers say countries that have not experienced a locust upsurge in many years are often ill-prepared to respond, lacking the necessary surveillance teams, aircraft and pesticides.

As climate change alters the movement and spread of major swarms, better planning is needed, making the new model a timely development, they added.