The Campaign for Responsible Rodenticide Use (CRRU) has published a new continuing professional development (CPD) guide to help rodent control professionals tackle the spread of rats that can survive high-potency rodenticides. Dr Alan Buckle, chair of the CRRU, suggests that all professionals and their suppliers can play a part in combatting the issue.

A University of Reading study last November found resistant rats in new locations. Researchers found the L120Q gene, which is responsible for the most severe form of resistance, for the first time in East Anglia and West Yorkshire. This gene renders first generation anticoagulant rodenticides and two of the second generation group virtually ineffective.

Rodenticide resistance is already widespread in central southern England and is now found increasingly outside that area. The Reading study also identified three different types of resistant rats in West Yorkshire and along the Anglo-Welsh border. Although resistance-breaking second generation anticoagulant rodenticides are available, Dr Buckle warns that they should be used very carefully, “because their effectiveness will be jeopardised by indiscriminate use, and they pose greater risk to the environment.”

A CRRU recommendation, if people are unsure of resistance, is to send a 2 to 3cm rat tail tip to the Vertebrate Pests Unit at Reading University for resistance testing. The service is free of charge, and detailed submission instructions are available. High priority areas where little is known about resistance include central England, Scotland and Northern Ireland, but tail samples are welcomed from all UK locations.

Dr Buckle says that, along with testing, rodenticide users should follow the CRRU Code of Best Practice, which includes monitoring the results of control treatments. “If this suggests rats are surviving well-implemented control programmes, it may indicate the presence of resistance,” he suggests.

The CPD guide can be downloaded via More information from Dr Alan Buckle, CRRU UK chairman, at email