Global warming could mean crop losses from insect damage double in ‘breadbasket of Europe’ by 2050

Rising global temperatures make insects 'even hungrier and more numerous'

Harry Cockburn
Friday 31 August 2018 00:41 BST
Crop damage by insects could rise by as much as 75 per cent in the UK
Crop damage by insects could rise by as much as 75 per cent in the UK (Getty)

Crops lost to insect damage in northern Europe’s most productive areas could double as global temperatures rise over the next 30 years, new research indicates.

Scientists forecast pestilence to soar in the area known as the “breadbasket of Europe”, resulting in crop damage in 11 countries including the UK, Sweden and Ireland rising by as much as 75 per cent by 2050, even if countries meet their existing commitments to reduce greenhouse gas emissions.

The study, published today in the journal Science, predicts increases in insect populations and in insects’ metabolic rates, as the world warms.

“In some temperate countries, insect pest damage to crops is projected to rise sharply as temperatures continue to climb, putting serious pressure on grain producers,” said Professor Joshua Tewksbury, co-lead author of the study and a research professor at the University of Colorado Boulder.

Insect damage currently reduces crop yields by 2.5 per cent. This means a 75 per cent increase in damage results in 4.4 per cent yield drop from insects. In total this would mean European wheat could see a total annual pest-induced yield losses topping 16 million tons, the study says.

Across wider Europe the study projects a 50 to 100 per cent increase in pest-induced crop losses in wheat, and across North America 30 to 40 per cent increases in losses of maize.

The research is based on estimates of a 1.7C-2C rise in global temperature – a possible scenario even if all countries meet their non-binding targets as agreed under the Paris climate agreement.

But the team warned that models assessing the agricultural effects of climate change rarely consider losses due to changing insect populations and behaviours.

In the near future a warmer climate means we should expect insects “to be even hungrier and more numerous”, the study warns. “Warmer temperatures have been shown to accelerate an individual insect’s metabolic rate, leading it to consume more food during its lifespan.”

And while pest populations may decline in some hotter tropical areas, they are expected to increase elsewhere as temperatures rise and new ecosystems become favourable to the insects.

The study argues that greater understanding of our crops and the ecosystems in which they function is required to ensure our food supplies.

Prof Tewskbury told The Independent: “Biological control of insect pests is successful when we have exceptional knowledge of the natural history of our crops and their relatives: where they grew, what insects ate the crops in the native range, what killed those insects. There is a lot of work to do to build that knowledge, and because our model is general – not specific to the three crops studied – we have reason to do this for all of our agricultural crops.

“That knowledge is out there to be gathered, and our inattention to this knowledge is perhaps the biggest threat to our food security.”

Professor Rob Dunn of North Carolina State University’s department of biological sciences told The Independent some of the main problems facing global food supplies include the narrow range of crops humans have cultivated, and the aggressive pesticides we have used on them.

He said: “The more we rely on relatively few crops (and relatively few pesticides) the faster the race with these pests and pathogens becomes. The better we will need to be at keeping up. Climate change is one more piece of this, it speeds everything up further by moving things around and stressing plants.

“In this light, we have to be really really clever and we have to know these crops and their associates really, really well. We haven't been, and we don't. We tend to know very little about the pests and pathogens of most crops, much less the species that help control them. Our databases are medieval.”

Scientists seeking to resolve the issues are also hobbled by ownership of data and the lack of coherent infrastructure between existing sets of data.

Prof Dunn added: “Where the data exist they have become privatised, such that in the current system we increasingly have to depend on a small handful of companies to keep up with pests and pathogens on our behalf. That is big trouble.

“It is time for a major initiative to rethink agriculture globally, to think about how to slow down evolution, how to keep the pests better at bay, how to rely on all of wild biodiversity's benefits, and how to, at the same time, eat and grow foods, sustainably.”

The study follows research indicating flying insects that crops are dependent on for pollination also face major threats.

Last year scientists warned of “ecological Armageddon” as the number of flying insects has plummeted by 75 per cent in the past 27 years, even in protected reserves in Europe.

Prof Dunn said: “Broad spectrum pesticides tend to kill insects in general, without regard to the their trophic level, but they are sprayed in ways that tend to favour the most rapid evolution in the species that are most abundant and breed most rapidly. In most cases that is the pests.

“The result in such scenarios can be loss of the species we most need and hyperabundance of the species we least want.

“At the same time, we are warming, drying and changing the planet, which again tends to favour species that are abundant and good at getting from place to place – again often the pests.

“A clever society would figure out a way to favour the evolution and persistence of biodiversity overall, and particularly beneficial species, but not of the species that threaten to tear our crops back to the ground. We have not yet proven ourselves, globally, to be such a society.”

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