Monitoring sugarcane moth borers in Indonesia: towards better preparedness for exotic incursions.
Sugarcane moth borers were surveyed on 931 farms across Java, Indonesia in 2008-09. Five moth borer species caused varying levels of damage to sugarcane plantations: Chilo auricilius, C. sacchariphagus, Scirpophaga excerptalis, Sesamia inferens and Tetramoera schistaceana. The first three were the most abundant. All five species caused 'dead hearts' in sugarcane, with S. excerptalis (top borer) being responsible for the majority of dead heart symptoms in both young and mature cane. Chilo species (stalk borers) cause dead hearts only in young cane and later tunnel inside cane stalks and damage the internodes. Farms managed by sugar factories suffered more S. excerptalis dead hearts than those managed by individual growers. This may be the result of crop diversification and shorter crop cycles practiced by individual farmers. In addition, S. excerptalis dead heart symptoms were more common in older ratoons, indicating progressive build up of infestation in older crops. C. sacchariphagus was more widespread in Java than C. auricilius, with the former species preferring irrigated areas while C. auricilius was more abundant in drier areas. S. excerptalis was equally abundant in both irrigated and rainfall areas. Parasitoid species recovered were Cotesia flavipes from C. sacchariphagus, Diatraeophaga striatalis from both Chilo species, and Rhaconotus roslinensis, R. scirpophagae, Stenobracon sp., Elasmus sp. and Isotima sp. from S. excerptalis. All moth borers have a high potential of colonising sugarcane in Australia, especially in central and north Queensland where climatic conditions are similar to conditions in their area of origin. Knowledge of the distribution and dynamics of these pests is essential to the development of sound Incursion Management Plans to ensure better preparedness for any incursion into Australia.