Identifying the impacts of climate change on key pests and diseases of plant and animal industries

Full text: Full text: Climate change is increasingly recognised as a major threat to natural and agricultural systems. Understanding these threats will enable government and primary industries to better prepare and adapt to climate change. While observations of climate change are well documented, the potential effects on pests, pathogens and their hosts are not clearly understood. To address this, a review of the potential impacts on plant biosecurity was undertaken to determine the effects of climate change on the behaviour and distribution of emergent plant pests and pathogens. The review identified increasing C02 and temperature, decreasing frost events, heavy and unseasonal rains, increased humidity, drought, cyclones and hurricanes, and warmer winter temperatures as influencing the behaviour of plant pests and pathogens. To study the effects of these changes in detail, three key plant biosecurity threats were analysed in case studies; wheat stripe rust, silver leaf whitefly and citrus canker. The predicted distribution of citrus canker was examined with increasing temperature scenarios using the bioclimatic model CLIMEX. The model predicted a southerly shift in the geographic range of the causal organism which would threaten the major southern citrus growing regions in future climates. A similar study on Bluetongue disease of sheep, spread by the Culicoides midge, also predicted a southerly shift in the vector's geographic range. Significant limitations were identified with bioclimatic modelling when examining the effects of climate change on pests and diseases. The model was unable to assess the plant and animal response to increasing temperature in conjunction with the pest. Also the influence of temperature on the life cycle of the organism, pathogenicity of strains, competition with other species, host coverage and the general effect on the biology of the organism could not be assessed. To begin to address this, a dynamic model was constructed using daily temperature data, coupled to plant physiology data and pest growth and population data for the Asian citrus psyllid (Diaphorina citri), vector of citrus greening disease, to determine the potential distribution and abundance of the insect in relation to climate change. This model will be built on to provide a more accurate prediction of the effects of climate change on plant and animal biosecurity and to develop contingency plans for government and industry to respond to and minimise the risks