Determining damage levels in wheat caused by Sunn pest (Eurygaster integriceps) using visible and near-infrared spectroscopy

Abstract

A commercial near-infrared (NIR) instrument for bulk samples and a modified Single Kernel Near-Infrared (SKNIR) instrument equipped with a visible or NIR spectrometer were studied as a way to measure damage levels caused by Sunn pest (SP) in wheat. Sunn pest causes damage by feeding on wheat berries and injecting a salivary enzyme damaging the gluten. For measurement of SP damage in bulk wheat, NIR calibration models developed for mixtures containing 0–10% and 0–100% sound and SP damaged wheat resulted in R2 of 0.25 and 0.89 and SECVs of 2.75 and 10.9, respectively. The 0–100% model was considered a qualitative measure of damage, but predictions were poor over 0–10% which is a critical range for commercial applications. Discrimination between single kernels of Sound and SP-damaged was typically good, with classification accuracy averaging ∼75% for both visible and NIR although some were poor, which greatly affected the average. Average classification accuracy was ∼85% for spectral data that contained kernels from all samples. While the potential for using visible or NIR spectroscopy was shown, results highlighted the need to develop a more robust SP classification model to further evaluate the single kernel model.