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Global warming linked with spread of crop-killing pests

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Fruit trees in mid-latitudes could face more pressure as global warming drives the spread of pests. bberwyn photo.

Trend poses food security threat

By Summit Voice

FRISCO — As global temperatures continue to rise, plant-killing pests are spreading toward the poles at the rate of almost two miles per year, posing a potential threat to food production in the world’s temperate crop–producing areas.

“If crop pests continue to march polewards as the Earth warms, the combined effects of a growing world population and the increased loss of crops to pests will pose a serious threat to global food security,” said Dr, Dan Bebber, of the University of Exeter.

Bebber and his colleagues carefully studied insect populations and climate trends, finding a strong relationship between increased global temperatures over the past 50 years and the expanding range of crop pests. The research was published Sept. 1 in Nature Climate Change.

Currently, about 10-16 percent of global crop production is lost to fungi, bacteria, viruses, insects, nematodes, viroids and oomycetes. The diversity of crop pests continues to expand and new strains are continually evolving. Losses of major crops to fungi, and fungi-like microorganisms, amount to enough to feed nearly nine percent of today’s global population. The study suggests that these figures will increase further if global temperatures continue to rise as predicted.

The spread of pests is caused by both human activities and natural processes but is thought to be primarily the result of international freight transportation. The study suggests that the warming climate is allowing pests to become established in previously unsuitable regions.

For example, warming generally stimulates insect herbivory at higher latitudes as seen in outbreaks of the mountain pine beetle that has destroyed large areas of pine forest in the western U.S.. In addition, the rice blast fungus which is present in over 80 countries, and has a dramatic effect both on the agricultural economy and ecosystem health, has now moved to wheat. Considered a new disease, wheat blast is sharply reducing wheat yields in Brazil.

“Renewed efforts are required to monitor the spread of crop pests and to control their movement from region to region if we are to halt the relentless destruction of crops across the world in the face of climate change,” said Professor Sarah Gurr, of the University of Exeter.

The study used published observations of the distribution of 612 crop pests collected over the past 50 years. It showed that the movement of pests north and south towards the poles, and into new previously un-colonized regions, corresponds to increased temperatures during that period.

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