Pests and diseases that attack crops are spreading with climate change, according to a study.
Researchers from the universities of Exeter and Oxford say the climate change is helping crop pests to move at an average of two miles (3km) a year.
According to the team, the pests were heading towards the north and south poles, and were increasingly populating areas that were at one time too cold for them to live in.
The research report was published in the journal Nature Climate Change.
According to estimates, currently between 10 per cent and 16 per cent of the world's crops are lost to outbreak of diseases. The problem could be getting worse due to increasing global temperatures.
According to Dan Bebber, the lead author of the study from the University of Exeter, global food security was one of the major challenges that the world would face over the next few decades.
There should be no further loss of crops to pests and pathogens than was absolutely necessary, he said.
To investigate the problem, the research team studied the records of 612 crop pests and pathogens from around the world that had been collected over the past 50 years.
Included in these were fungi, such as wheat rust, which was devastating harvests in Africa, the Middle East and Asia. The study also included insects like the mountain pine beetle responsible for destroying trees in the US; as also bacteria, viruses and microscopic nematode worms.
According to the researchers, crop pests were moving into new areas at a quicker rate than their predators, meaning they could inflict more damage to crops.
It might be harder for wild species to move due to the fragmentation of their habitats due to deforestation, farms, roads or cities. Bebber said pest species were constantly being shifted around the world by trade.
Gary Yohe, a professor at Wesleyan University in the US said he was not surprised at the spread of pests, which is faster than that of wild animals and plants. Yohe was co-author of the 2003 study, which estimated the average poleward shift at 6.1 km.
A tiny pest was more likely than the average animal or plant to be inadvertently carried, taken on a train, truck or airplane to a new area, he said, adding that the 2003 study was conservative.
According to Michael Singer, a professor at both Plymouth University in England and the University of Texas, another possibility was that the rate of movement by wildlife had really speeded up.