John Craven: Climate change could create a new army of pests

The Countryfile presenter examines how climate change could affect Britain's crops

Farming rape field

It is an arable farmer’s nightmare: vast armies of ravenous insects chomping their way through Britain’s wheat fields as the world gets warmer. But that is the pestilential prediction for the middle of this century in a new study warning pest damage to crops could double. It claims that in the “bread-basket of Europe”, which consists of the UK and 10 other countries, up to 14.5 million tonnes of wheat a year could be lost.

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The study, by the University of Colorado and reported in the journal Science, is based on an estimated rise of between 1.7°C and 2°C in global temperatures by 2050, which is within the bounds of the Paris accord on climate change agreed by all world leaders, apart from Donald Trump. Its authors expect insects to be hungrier and more numerous, because “warmer temperatures have been shown to accelerate an individual insect’s metabolic rate, leading it to consume more food during its lifetime”.

So just how worried should we be? “There will be a new set of challenges for farmers to deal with, in particular the speed of change,” Dr Ceris Jones, climate change advisor to the National Farmers’ Union, tells me. “Insects are cold-blooded, so even small changes in temperature can make a big difference to population size.”

Tractor working in field of wheat
Tractor working in field of wheat (Getty)

Insect monitoring 

“We have often relied on cold winters to kill off bugs,” she adds. “If winters get warmer, that won’t be the case, and already the average temperature in central England has increased by almost 1°C. But it’s not just rising temperatures that affect plants and insects; there are other complex considerations, such as humidity, rainfall, droughts, and the impact of other creatures, such as predators in the same habitats,” she explains. “I believe much more emphasis needs to be placed on monitoring what’s happening out in the fields if we are to avoid serious problems.”

We have often relied on cold winters to kill off bugs. If winters get warmer, that won’t be the case, and already the average temperature in central England has increased by almost 1°C.

Matt Shadlow, of the charity Buglife, agrees. “It’s difficult to find information about the status and distribution of pest species, knowledge that could be vital in years to come. When you look on the National Biodiversity Network Atlas (the UK’s largest collection of freely available data) for details of common agricultural pests, for some there just aren’t any records, which is bonkers. It would make sense to have a scheme that monitors all invertebrates flying around our countryside to give us a much better picture.”

He says one pest that has plagued arable farmers, the orange blossom midge, is in almost every wheat field, but there is no mention of it in the atlas. It can now be controlled, but a new threat emerged this summer in the form of the lemon blossom midge. The hot weather enabled its larvae to hatch at just the right time to eat like gangs into wheat seeds. A control method for this latest menace will be urgently needed.

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“But clever techniques that combat pests could be out of the window if the temperature rises by half a degree,” says Matt. “We are good, though, at adapting and we will find ways to mitigate the worst effects of climate change. My fear is that before we get good solutions we might see more frequent use of harmful insecticides.” If the researchers are right and the UK faces future invasions of hungry bugs, it would seem to be in the national interest that we are properly forewarned and forearmed.