1 September 2013
Crop pests relentless in their march polewards
by Will Parker
A new study has revealed that our warming climate is pushing crop pests such as fungi, bacteria, viruses, insects, and nematodes, towards the North and South Poles at a rate of nearly 3 km a year. The study, published in the journal Nature Climate Change, shows a strong correlation between increased global temperatures over the past 50 years and the expansion of crop pest territories.
Currently, around 13 percent of global crop production is lost to pests. The study suggests that these figures will increase further if global temperatures continue to rise as predicted. While the spread of pests is caused mainly by human activities such as international freight transportation, the warming climate is allowing transported pests to become established in previously unsuitable regions.
The study was based on published observations of the distribution of 612 crop pests collected over the past 50 years. It revealed 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.
Study author Dan Bebber, from the University of Exeter, said that warming generally stimulates insect herbivory at higher latitudes; as seen in outbreaks of the Mountain pine beetle (Dendroctonus ponderosae) that have destroyed large areas of pine forest in the US Pacific Northwest. "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," he added. "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."
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Source: University of Exeter