Sensitivity of some Australian animals to sodium fluoroacetate (1080): additional species and populations, and some ecological considerations

The sensitivity to fluoroacetate ( 1080) of a number of species of rodents and dasyurids with and without evolutionary exposure to fluoroacetate-bearing vegetation was determined. Rattus fuscipes, and species of Pseudomys from populations with exposure to this vegetation, were particularly tolerant to fluoroacetate. However, the level of tolerance varied among the different populations of each species, depending on the degree to which the toxic plants were present in their microhabitat. The tolerance of the F1 offspring of sensitive R. fuscipes ( South Australia) crossed with tolerant conspecifics from Western Australia was mid-range between those of the parental populations. The sensitivity of introduced R. rattus and Mus domesticus from areas with fluoroacetate-producing plants in Western Australia was similar to that reported elsewhere for these rodents. This suggests that their relatively short coexistence with the toxic plants has had little obvious impact on their level of sensitivity to fluoroacetate. The dibbler, Parantechinus apicalis, which coexists with the toxic vegetation, was exceptionally tolerant for a native carnivore/insectivore (LD50 similar to35 mg 1080 kg(-1)). In contrast, however, Phascogale tapoatafa from southern Western Australia was more sensitive to 1080 than was expected, with an estimated LD50 of 7 mg 1080 kg(-1). Although the level of tolerance to fluoroacetate was seen to vary depending on the level of exposure of each species/ population to fluoroacetate-bearing vegetation, our findings provide further evidence of the evolutionary impact that fluoroacetate-producing plants appear to have had on the genetic composition of indigenous Australian fauna.