Incursion preparedness: anticipating the arrival of an economically important plant pathogen Xylella fastidiosa Wells (Proteobacteria: Xanthomonadaceae) and the insect vector Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) in Australia
The glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), is an important insect vector of the xylem-limited plant pathogen Xylella fastidiosa Wells et al. that causes diseases in numerous plant species including food and feedstock crops, ornamentals and weeds. Both the pathogen and the vector are native to the Americas, and H. vitripennis has demonstrated high invasive ability but to date neither has been detected in Australia. The Australian wine grape, table grape, peach, plum, nectarine and citrus industries are particularly concerned about the arrival of X. fastidiosa and H. vitripennis because of the potential economic impact on these important commodities. Other commodity producers in Australia should also be concerned about this vector-pathogen, in particular the ornamental plant, avocado and olive industries. Past interceptions of H. vitripennis and the potential for X. fastidiosa to be moved in live plant material or within live vectors indicate the need for rapid detection of an incursion in areas considered at high risk. This requires identification of regions that have climatic and environmental conditions conducive to X. fastidiosa and H. vitripennis establishment as well as a detailed knowledge of their respective potential host plant ranges in new areas. These climatic regions and host plant species can then be targeted for monitoring in order to detect an incursion at an early stage. CLIMEX modelling has shown that much of coastal Australia has temperatures suitable for survival of both the vector and pathogen. A range of other requirements in addition to suitable climate must, however, be satisfied for an incursion to lead to establishment, proliferation and spread. This review article provides information that shows that the Australian environment is suitable for the establishment of H. vitripennis and that Australian native plant species are likely to serve as X. fastidiosa hosts and subsequent pathogen sources, and highlights future research directions.