2 April 1999

Call to use indoor rat baits outdoors

CONTROLLED outdoor use of baits currently approved for indoor use only may be the best way to keep rats at bay, minimise resistance and protect other wildlife.

Previously safe products were effectively being rendered unsafe by resistance, Robert Smith of Leics University told a seminar organised by Pest-Ventures in Derbyshire.

New trials suggest that rats gorging themselves on ineffective rodenticides are not only a nuisance on farms but also a significant threat to predators such as owls and the red kite. "They become parcels of poison with four legs and a tail."

Resistance to bromodialone (Endorats, Slaymor, Tomcat) and difenacoum (Rataway, Neokil, Neosorexa, Ratak, Killgerm Rat Rods and Wax Bait), two second generation anticoagulants, which have widely replaced resistance-prone warfarin, is well documented in Berkshire. Newbury District Council no longer undertakes rat control contracts on pig and poultry farms because of it, said the councils Mick Qwelch.

So far that type of resistance is still confined to a relatively small area, the CSLs Roger Quy noted. But how best to ensure it stays that way is not clear.

No coherent strategy

"MAFF appears to have no coherent strategy to deal with it," said chairman, Adrian Meyer of PV.

Easing the restrictions on the more effective anticoagulants brodifacoum (Klerat) and flocoumafen is one way forward, Prof Smith argued. Oxon farmer Stephen Hart backed that view. "The situation is fast getting out of control. We are sitting on a time-bomb."

David Richardson of the Pesticides Safety Directorate said outdoor use of brodifacoum had been considered by the Advisory Committee on Pesticides in 1992, but deemed too risky.

The Leics University data might trigger a fresh assessment but would need widespread evidence before any change of approval. &#42

RESISTANT RATS

&#8226 Few rodenticides.

&#8226 Wildlife concerns.

&#8226 Approval change?

&#8226 Uniform strategy need.