Rising temperatures around the world are forcing hundreds of crop pests from the tropics towards the North and South poles at a rate of nearly two miles a year, according to a study carried out by researchers at the University of Exeter and the University of Oxford in England and published in the journal Nature Climate Change.

The team stated that they are moving to locations that were once found to be too cold.

"The most convincing hypothesis is that global warming has caused this shift. One example is the Colorado potato beetle. Warming appears to have allowed it to move northwards through Europe to into Finland and Norway where the cold winters would normally knock the beetle back," study author Dr. Dan Bebber from the University of Exeter said.

"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," Bebber said.

Researchers arrived at the conclusion, after studying 612 crop pests and pathogens collected over the past 50 years that have threatened the food resources in Africa, the Middle East and Asia.

They found that, on an average, species were shifting towards the north and south poles at about 1.7 miles (2.7km) per year.

"We detect a shift in their distribution away from the Equator and towards the poles," Bebber said.

Climate change has driven a serious weather-sensitive pest, mountain pine beetle, Denroctonus ponderosae northward, which is destroying large areas of pine forest in the US Pacific north-west.

The scientists wrote: "Observed changes in pest distributions accord with observations of wild species, direct responses of pests to warming, and with expectations for expanding pest ranges under climate change."

Another example is the rice blast fungus, a dangerous pest affecting more than 80 countries. It is usually known for destroying rice crops and is attacking wheat too. Now named wheat blast, this pest is destroying crops in Brazil and is expected to spread further north to the U.S.

"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," Co-author Professor Sarah Gurr, from University of Exeter, said.