Yields of maize, wheat and rice in northern climates are projected to fall as insects thrive in warmer climates.

Researchers from the University of Colorado at Boulder calculated the potential for crop damage through to 2050, by combining climate projection data, insect metabolic rates, crop yield statistics, and other demographic information.

The researchers modelled an increase in the number of insects in a warmer world, predicting a 50 to 100 per cent increase in pest-induced crop losses in European wheat, with 30 to 40 per cent increases in North American maize. The researchers predict this will occur even if countries meet existing commitments to reduce greenhouse emissions.

Insect pestilence already reduces the net yields of three staple grains; wheat, maize and rice. These grains combined provide 42 per cent of the total calorie consumption worldwide. Current models assessing the agricultural effects of climate change rarely take insects into consideration.

Researchers found that European yields are likely to be hit the hardest. As Europe is currently the most productive wheat producing region, pest impacts could create losses amounting to 16 million tons. Denmark, Sweden, Ireland and the UK are expected to see an increase of 75 per cent in insect-induced crop losses.

Major losses are also expected in North America and Asia, with the US seeing a 40 per cent increase in insect-induced maize losses – a reduction of 20 million tons annually, while China may see losses of 27 million tons of rice annually.

“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-leader of the research.

The researchers mention that future insects in a warmer environment are expected to be even hungrier and more numerous. Warmer temperatures have previously shown to accelerate an insect’s metabolic rate, leading to the consumption of more food during its lifespan.

“On average, the impacts from insects add up to about a 2.5 percent reduction in crop yield for every degree Celsius increase in temperature,” said Prof Tewksbury. “For context, this is about half the estimated direct impact of temperature change on crop yields, but in north temperate areas, the impact of increases insect damage will likely be greater than the direct impact of climate on crop yields.”

The researchers suggest changes to agricultural practices, including an increase in the selection of pest- and heat-resistant crops, and new crop rotation patterns.

The study was published in the journal Science.

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