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Crop Pests, Diseases Move to Higher Latitudes

Warmer conditions brought on by climate change are producing more hospitable environments for pests such as the emerald ash borer (seen here).

Warmer conditions brought on by climate change are producing more hospitable environments for pests such as the emerald ash borer (seen here).

Insects and diseases that attack food crops are moving to higher latitudes as climate change alters their habitats, according to a new study published in Nature Climate Change.

With the bulk of the world’s agricultural production today taking place in the temperate zones, the study raises questions about future food security in a warming world.

Plant diseases alone claim an estimated 10 to 16 percent of the world’s crops in the field, experts say, and destroy another 6 to 12 percent after harvest.

Meanwhile, research has shown wild plants and animals are moving toward the poles as the planet gets warmer.

And the U.S. Department of Agriculture is adjusting northward its map of zones suitable for growing certain crops.

“That got us thinking,” said biologist Dan Bebber at the University of Exeter in Britain. “Is a similar process occurring with pests and pathogens that attack our agricultural crops?”

Hundreds of pests

To find out, Bebber turned to reports of first sightings of new insects and diseases around the world. The data came from the agriculture research organization CABI, which began collecting the information from developing and industrialized countries about a century ago and now tracks hundreds of pests and pathogens around the world.

Bebber and his colleagues studied 612 of them - from viruses and bacteria to beetles and butterflies - and found that since 1960, they had shifted toward the poles at an average rate of about 3 kilometers per year.

That puts some of the most productive farmland in the world in danger.

“As new species of pests and diseases evolve and potentially the environment for them becomes more amenable at higher latitudes, the pressure on the breadbaskets of the world is going to increase,” Bebber said.

Invasive hospitality

Farmers have other emerging threats to deal with, as well. Invasive species introduced through global trade and mobility also are a threat to crops. Entomologist Gene Kritsky at Ohio's College of Mount St. Joseph said climate change may make the environment more hospitable for some invasive species.

“It means that species in other parts of the world that might do well in warmer temperatures can now do well in the breadbasket of America.”

Kritsky was not involved in the research, but said it confirms what he’s seen in the field. He added that more species will be able to survive the winters at higher latitudes as temperatures increase.

'We should do something'

Entomologist Christian Krupke at Purdue University in Indiana pointed out that the effects of these shifts will depend very much on the crop, the pest and the disease.

But he said that the research is another warning sign of what may be in store for the future.

“I think a lot of these papers are all pointing in the same direction that are all saying, ‘OK, we should care about climate change. We should do something other than zero,’” he said.
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    Steve Baragona

    Steve Baragona is an award-winning multimedia journalist covering science, environment and health.

    He spent eight years in molecular biology and infectious disease research before deciding that writing about science was more fun than doing it. He graduated from the University of North Carolina at Chapel Hill with a master’s degree in journalism in 2002.

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