Current research aims to help the virus stay ahead in the co-evolutionary arms race with its rabbit host, to protect the gains made by the past successful biocontrol initiatives and to keep rabbit numbers below the damage threshold. Keeping their numbers low over long periods of time is essential for Australia's biodiversity and rural industries. Some rabbits in cool, high-rainfall areas carry a benign virus that gives them partial immunity to the virulent calicivirus.īiological control is by far the most cost effective large-scale control option for rabbits. Within 18 months RHDV2 spread across the entire continent and became the dominant RHDV strain in Australia, leading to an estimated reduction of 60 per cent on average of wild rabbit populations. In 2015 we identified an additional strain of calicivirus, termed RHDV2, in Australia. However, evidence for developing resistance in some Australian wild rabbit populations has now been described, and rabbit numbers are again on the rise. RHDV kept rabbit numbers low for over a decade and, unlike Myxomavirus, a reduction in virulence has so far not been observed. RHDV again reduced rabbit numbers to very low levels, with greatest impact in arid zones and lesser impact in high rainfall areas. In 1996 Rabbit Haemorrhagic Disease Virus (RHDV), a calicivirus, was officially released in Australia. However, by the late 1950s, host-pathogen co-evolution led to a less severe form of the disease, and rabbit numbers increased again, although not to pre-1950 levels. It was the world's first successful biological control program of a mammalian pest, taming a scourge that had threatened Australian agriculture and environment.

Due to their selective grazing habits, less than one rabbit per hectare can completely prevent the regeneration of certain native tree and shrub species that are palatable to rabbits. The damage caused by rabbits ranged from massive grazing pressure and competition with livestock to spreading weeds and accelerating erosion, and many farms were abandoned during the peak of the rabbit plaque.Įven today, with rabbit numbers still at a fraction of pre-Myxomatosis levels, rabbits cause an estimated AUD$200 million per year of economic damage, in addition to countless detrimental effects on biodiversity. Within 70 years they spread to 70 per cent of Australia's landmass, the fastest known invasion by a mammal anywhere in the world. After a fire destroyed the enclosures, rabbits started their campaign to conquer Australia. Rabbits were introduced to Australia in 1859 by a wealthy Victorian grazier keen on the sport of hunting. By 1950 rabbit numbers in Australia reached 600 million.

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