Sugar crop yield vs cane toads

In 1935, cane toads (Rhinella marina) were brought to Australia to control
insect pests. The devastating ecological impacts of that introduction have
attracted extensive research, but the toads’ impact on their original
targets has never been evaluated. Our analyses confirm that sugar
production did not increase significantly after the anurans were released,
possibly because toads reduced rates of predation on beetle pests by
consuming some of the native predators of those beetles (ants), fatally
poisoning others (varanid lizards) and increasing abundances of
crop-eating rodents (that can consume toads without ill-effect). In short,
any direct benefit of toads on agricultural production (via consumption of
insect pests) likely was outweighed by negative effects that were mediated
via the toads’ impacts on other taxa. Like the toad’s impacts on native
wildlife, indirect ecological effects of the invader may have outweighed
direct effects of toads on crop production.