Biological control of the cane toad in Australia: a review

Abstract

The marine toad Bufo marinus is native to northern South America, parts of Central America and Southern Texas. It was deliberately introduced into Australia's tropical north-east in 1935 in an unsuccessful attempt to control the cane beetle, a damaging insect pest of sugarcane crops. The toads quickly established in the new environment and began to spread. Today, they inhabit most of the Australian tropics and sub-tropics and have reached Western Australia. Models predict that global warming will enable the toads to extend their range further south. They cause severe environmental impacts, as all life stages of B. marinus contain bufadienolides, alkaloid substances toxic to vertebrates, resulting in death of the predators ingesting it. The continental scale of this biological invasion in combination with the remoteness of the areas affected, poses a specific set of challenges to potential control approaches for cane toads. This review covers different biocontrol strategies pursued over the past 8 years, with particular focus on an immunological approach aiming at the disruption of toad metamorphosis. So far, research efforts have failed to produce a tool for large-scale reduction of toad populations. Considerations of future research priorities and efforts are also discussed.