FARMERS HAVE been asked to collect tail samples from freshly killed rats and mice so that they can be analysed for rodenticide resistance genes.

Issuing this appeal, the Campaign for Responsible Rodenticide Use has asked participants to read the guidelines from the University of Reading's Vertebrate Pests Unit, where the genetic testing is being done. The deadline for sample submissions is May 29 and every sender will be notified of their own results.

The guidelines are available at https://research.reading.ac.uk/resistant-rats/ and a factsheet with the same information can be downloaded from thinkwildlife.org/downloads/.

In the past two years, new hotspots of rats with resistance genes have been found in Northumberland and County Durham, Tyneside and North Yorkshire, Greater Manchester and along the River Severn valley, from north-west Shropshire to Somerset, Devon and East Anglia.

Over a number of years, rodenticide resistance genes have become widespread across central southern England. Leader of CRRU’s Monitoring Work Group, Richard Moseley, said a serious concern was the almost complete lack of data from central England and most parts of Scotland, Wales and Northern Ireland.

"We can only manage the spread of resistance when we know where it is," he said. "Currently we have the worst of both worlds. Farmers, pest control technicians and gamekeepers could be using products that are ineffective in places where rodents are resistant. And where resistance genes are still absent, others may be using resistance-breaking products unnecessarily. Only more samples can solve this."