In other, less dramatic and less well-known, cases insects, parasites or diseases have been introduced into Australia to attack and control pests or predators. Introduced parasitic wasps, for example, have successfully limited, although not eliminated, the predations of the green vegetable bug and the cabbage butterfly.

A major program undertaken by CSIRO during the last twenty-five years has sought to encourage the spread of imported dung beetles throughout Australia. Because cow dung fouls pastures and produces rank, unpalatable forage, and because dung pads also constitute breeding grounds for pests such as buffalo fly and bushfly, it was hoped that the beetles would effectively bury or otherwise dispose of concentrations of dung. Although some 55 species and 16 strains of dung beetle were brought to Australia, mainly from Africa, during the period 1968 to 1978, and at least nine species are now firmly established in northern Australia, the results of the program have been variable and its economic impact has been difficult to assess.

Several experimental programs are currently being undertaken to examine the feasibility of biologically controlling many extremely important pests (such as sheep blowflies, lucerne fleas, redlegged earth mites, spotted alfalfa aphids, and cocksfoot grubs) and weeds (such as ragwort and heliotrope). However, the example of biological control which, more than any other, is associated with Australia concerns the control of rabbits.

Myxomatosis and rabbit control

The first (domesticated) European rabbits, Oryctolagus cuniculus, to arrive in Australia came with the First Fleet in 1788 and further batches arrived during the next 50 or 60 years. Although reports from Tasmania had spoken of feral rabbits in alarming numbers as early as 1827, the animals which eventually overran the southern half of mainland Australia were descendants of 24 wild rabbits that Thomas Austin, a Victorian landholder, imported from England on the clipper Lightning in 1859. From the Austin property at Barwon Park, some 30 km west of Geelong, the initial population spread with alarming speed until, by 1880, they had crossed the River Murray into New South Wales. Travelling north at a rate of over 100 km a year they reached Queensland in 1886. At similar speeds they migrated west, through South Australia, to Western Australia, reaching the Indian Ocean north of Geraldton, WA, 16 years after they had first been sighted at Fowler's Bay, South Australia, a distance of more than 1700 km.

At great expense and with much difficulty fences were constructed, one of which stretched for more than 1500 km across Western Australia, in a vain attempt to stop the vermin from spreading even further Despite all such efforts the rabbit became established over more than half the continent, stopping only when the climate became too extreme, the soil too heavy, the forest vegetation too thick, or the available grazing too sparse.

Australian Academy of Technological Sciences and Engineering