Crop pests and pathogens have shifted polewards by an average of almost three kilometres per year since 1960. These findings, published online this week in Nature Climate Change and based on analysis of past observations of hundreds of pests and pathogens, support the hypothesis of climate-driven pest movement.

The emergence and spread of crop pests - which include fungi, bacteria, viruses and insects - present a significant challenge to food security, with the Irish Potato famine in the 1840s being perhaps the most famous example. Although the spread of pests is known to be facilitated primarily by human transportation, there is increasing concern that climate change could allow for the expansion of pests into previously unsuitable regions.

Sarah Gurr, Dan Beber and colleagues tested this hypothesis using published records of pest occurrence over the past 50 years. Observational bias - where more developed countries at high latitudes are likely to detect pests earlier than developing countries at low latitudes - would be expected to lead to an apparent shift towards the equator, the opposite of what was actually found. This lends support to the strength of the trends detected.