The toxicity of brodifacoum to susceptible and warfarin-resistant Rattus tiomanicus (Miller)

C.H. Lee and K.A. Kamarudin

Abstract

The toxicity of brodifacoum was evaluated by oral intubation with wild (susceptible) R. tiomanicus. No-choice feeding studies with warfarin-resistant  and susceptible rats of the same species were undertaken to determine the efficacy of the compound. The single oral dose (LD56) for brodifacoum was 0.31( 0.26-0.36)mg/kg and the mean lethal feeding period (LFP50)w as0 .68 (0.05-0.98) day. The LFP₅₀ for the warfarin-resistant rats was twice more than that of susceptible rats' All the rats died between a mean of 5 days and 9 days. Total death of warfarin-resistant rats was achieved in a 4-day feeding period. The LFP₉₉ determined with susceptible rats gave a 3-day feeding period and this was used as the baseline for monitoring rat resistance to brodifacoum. The warfarin-resistant rats exhibited tolerance to brodifacoum with a certain degree of cross resistance. Brodifacoum was found to be an effective rodenticide against warfarin-resistant  and susceptible rats. Its favourable properties include good bait acceptance, a single dose poison and short duration to death.

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