Abstract

Vertebrate pests constitute a wide variety of species, from jawless fish to eutherian mammals, on geographic scales ranging from local to continental. Biological control involves the use of another organism: predators, microparasites (bacteria, viruses, protozoa, fungi) or macroparasites (helminths, arthropods), to control a pest population. The introduction of novel high-order predators as biological control agents for vertebrates has generally been unsuccessful, unless the pest population has first been reduced by other means, and has led to significant unforseen ecological consequences. Biological control using microorganisms has only three successes: myxomatosis and rabbit hemorrhagic disease for European rabbits and a single example of the use of feline panleukopenia to control cats. In each case, initial spectacular success has been tempered by subsequent rebound of the populations, albeit slowly, and to lower levels than before the introduction of the pathogen. The only successes with macroparasites are the introduction of two species of flea into Australia as vectors for the virus causing myxomatosis. A number of other attempts to use biological control and prospective biological controls including biotechnology are briefly reviewed. It is challenging to find safe and effective biological controls for vertebrate pests and even highly successful controls have not replaced the ongoing need for conventional controls as part of an integrated pest management strategy, but they have made it a lot harder for the pest to maintain high populations.