New toxin delivery systems for small mammal pests

Abstract

Introduced rats continue to have a major impact on biodiversity around the world, and improved control techniques are required to avoid further extinctions. We are trialing resetting toxin-delivery systems (Spitfires) targeting a range of predators, including rats. The Spitfire works by firing a paste containing a toxin on to the belly of rats as they pass through a tunnel. The device then resets. When the rats groom the paste from their fur, they ingest the toxin. Each Spitfire is capable of approximately 100 doses and is fitted with a counter and a delay mechanism. Sodium fluoroacetate (1080), zinc phosphide and brodifacoum have been successfully pen trialed in Spitfires on both wild Norway rats (Rattus norvegicus) and black rats (R. rattus). A 4-week field trial was undertaken in summer using 35 Spitfires containing 1080, spaced on a 100-m grid covering 24 ha. Rat tracking rates in the non-treatment area were 55% before the trial and 80% after. In the treatment area, they were 33% before and 7%after. Gas leakage was a problem in a number of the Spitfires, causing them to malfunction and this fault is currently being rectified.