A re-evaluation of potential rodenticides for aerial control of rodents

Abstract

Rodent control is carried out extensively in New Zealand to protect the native fauna and flora. This review outlines the advantages and disadvantages of different rodenticides as alternatives to sodium fluoroacetate (1080), and their suitability for aerial application. It includes existing rodenticides and those in the registration ‘pipeline’, as well as those that are not currently available in New Zealand. In the short to medium term, the focus for aerial baits should be on those compounds already registered in New Zealand or other countries. Aerial brodifacoum baiting is appropriate in isolated situations, but is not suitable for repeated use on the mainland, as brodifacoum is highly persistent and will bioaccumulate. Diphacinone has been registered for field use in New Zealand and the US Environmental Protection Agency has recently registered it for aerial control of rodents for conservation purposes; therefore, this is a logical first choice for control in New Zealand. Cholecalciferol is the next best option, as there is no secondary poisoning and thus there would be lower risk to non-target bird species; this is currently registered for field use as a rodenticide in bait stations. The third option is cholecalciferol in combination with coumatetralyl, which should be more effective than cholecalciferol alone, and the fourth is zinc phosphide. In the longer term, the preferred alternative to 1080 would be a novel, humane red blood cell toxin, related to para-aminopropiophenone (PAPP). PAPP is an attractive new pesticide that is being developed for stoat (Mustela erminea) and feral cat (Felis catus) control; however, the rodenticidal potential of this class of compounds still remains to be determined. Availability and registration status could influence this priority list in the future. A strategy to manage mice (Mus musculus) and sustain rat (Rattus spp.) control needs to be flexible and integrate non-anticoagulant and anticoagulant use.