By Stephen Beech
A new early warning tool developed by British scientists will help control devastating locust swarms.
Desert locusts typically lead solitary lives until something – such as an intense rainstorm – triggers them to swarm in vast numbers and to wreak havoc, say scientists.
The migratory pest can reach plague proportions, and a swarm covering one square kilometer can eat enough food in one day to feed 35,000 people.
Such extensive levels of crop destruction push up local food prices and can lead to riots and mass starvation.
Now, a team led by University of Cambridge scientists has developed a way to predict when and where desert locusts will swarm, so they can be dealt with before the problem gets out of hand.
It uses weather forecast data from the UK Met Office, along with state-of-the-art computational models of the insects’ movements in the air, to predict where swarms will go as they search for new feeding and breeding grounds.
The areas likely to be affected can then be sprayed with pesticides.
Until now, predicting and controlling locust swarms has been ‘hit and miss’, according to the research team.
Thr new model, described in the journal PLOS Computational Biology, will enable local authorities to respond quickly to a developing locust 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, and capable of long-distance travel across national borders.
The research team says climate change is expected to drive more frequent desert locust swarms, by causing trigger events such as cyclones and intense rainfall.
Such events bring moisture to desert regions that allow plants to thrive, providing food for locusts that trigger their breeding.
Study first author Dr. Renata Retkute, of Cambridge’s Department of Plant Sciences, said: “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.
“And if they’re not controlled at those sites, we can predict where they’ll go next so preparations can be made there.”
Study senior author Professor Chris Gilligan said: “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 the future, rather than starting from scratch as has historically been the case.”
The team noticed the need for a comprehensive model of desert locust behavior during the response to a massive upsurge from 2019 to 2021, which extended from Kenya to India and put a huge strain on wheat production in those regions.
The infestations destroyed sugarcane, sorghum, maize and root crops.
The research team says the scientific response was hampered by the need to gather and integrate information from a range of sources.
Dr Retkute said: “The response to the last locust upsurge was very ad-hoc, and less efficient than it could have been.
“We’ve created a comprehensive model that can be used next time to control this devastating pest.”
Although similar models have been attempted before, she said the new one is the first that can rapidly and reliably predict swarm behavior.
Dr. Retkute added: “It takes into account the insects’ lifecycle and their selection of breeding sites, and can forecast locust swarm movements both short and long-term.”
The new model has been tested using real surveillance and weather data from the last major locust upsurge.
It will inform surveillance, early warning, and management of desert locust swarms by national governments, and international organizations including the Food and Agriculture Organization of the United Nations (FAO).
The researchers say countries that haven’t 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, the team warned that better planning is needed – making the new model a timely development.
