New biological control opportunities for prickly acacia: exploration in India.

Prickly acacia (Acacia nilotica subsp. indica), a multipurpose tree in its native range, is a Weed of National Significance in Australia. It is widespread throughout the grazing areas of western Queensland and has the potential to spread throughout northern Australia. Biological control research has been in progress since the 1980s, but with limited success to date. Climatic modelling and genetic studies have indicated that the search for biological control agents should be concentrated in India, the source of the prickly acacia populations in Australia. Hence, a project was initiated in India to conduct surveys in Tamil Nadu and Karnataka States in southern India, and Rajasthan and Gujarat States in northwest India. Surveys in India commenced in July 2008, and the survey sites include both natural groves and forestry plantations. So far, 77 insect species and 14 diseases have been recorded in Tamil Nadu and Karnataka, while 14 insect species and 11 diseases have been documented in Rajasthan and Gujarat. Among them, a leaf-webbing caterpillar, a scale insect, two species of leaf-feeding weevils and a rust fungus infecting leaves and inducing galls on rachis and pods have been prioritised for host specificity studies