Chapter 4 Climate Impacts and Responses

Impacts of Climate Change on Australia > Pests and weeds

Australia’s crops, horticulture and forestry are vulnerable to introduced pests that have no local biological controls. Climate change may increase the chance that such pests will become established. Researchers at the CRC for Australian Weed Management Systems have found that the moths, weevils and beetles that play a vital role in biocontrol of weeds are suffering severely in the current drought. The latest bitou biocontrol agent, the leaf rolling moth Tortrix, has not established as well as predicted in the two years since initial release. Bitou bush is a native of southern Africa. It is rated as the worst pest plant in the Australian coastal environment, restricting access to beaches and destroying native bushland. This invasive species is being affected by the dry conditions, in turn affecting the biocontrol agents that attack it. The leaves of bitou bush become tough and lose nutritional value. This makes it very difficult for the young larvae to get a niche amongst the growth tips. Ants and spiders, short of their normal food, are also devastating the control agents. In the north of the state, Agriculture NSW has been rearing and releasing agents.

Researchers at the University of Queensland and CSIRO (White et al. in press) investigated the vulnerability of the Australian beef industry to the cattle tick Boophilus microplus under climate change. Compared to current estimated losses of 6000 tonnes per year, they found potential losses in live weight gain from 7800 tonnes per year by 2030 to 21,600 tonnes per year by 2100. These figures are in the absence of adaptation measures such as changing to tick-resistant breeds or increasing tick control treatment.