Towards a rapid near-infrared technique for prediction of resistance to sugarcane borer Eldana saccharina Walker (Lepidoptera: Pyralidae) using stalk surface wax

Multiple regression predictive models based on data acquired by near-infrared (NIR) spectrophotometry suggest that stalk surface wax components contribute towards resistance to Eldana saccharina Walker in sugarcane. At least 35 sugarcane clones of known resistance were required to calibrate a predictive model that accounted for approximately 54% of the variation in resistance to Eldana. Wavelengths chosen in multiple regression models suggest that alcohols and carbonyls are important in the wax contribution. Through the use of wax fractionation and gas chromatography, a high alcohol/aldehyde ratio and shorter carbon chain length appears to be associated with resistance. The use of NIR in the screening of wild germplasm and the early screening of breeding material for resistance, without prior knowledge of the biochemical mechanisms involved, is an exciting prospect. However, cause-and-effect relationships remain to be shown.