Xanthogalerucella luteola (Col.: Chrysomelidae) α-amylase affected by seed proteinaceous extract from datura, wild oat and amaranth seeds

The elm leaf beetle, Xanthogalerucella luteola (Muller) (Col.: Chrysomelidae) is a serious pest of elm trees and it has been distributed all over the world. The current study was undertaken to investigate the inhibitory effects of protein extracts of three weed seeds including datura Datura stramonium L., amaranth Amaranthus retroflexus L. and wild oat Avena fatua L. against X. luteola α-amylase using spectrophotometric assay as well as in gel assays. The effects of five concentrations of each seed proteinaceous extracts were tested on α-amylase activity of the larval gut. The results showed a dose dependent manner in inhibition of the insect enzyme. At the highest concentration of protein extracts (12 μg protein) of all three seed extracts including amaranth, wild oat and datura, the inhibition was 71, 79 and 31%, respectively. Whilst, at low concentration (0.75 μg protein), the inhibition observed was 15, 36 and 5%, respectively. Thus, the greatest inhibition percentage was obtained when proteinaceous extract of wild oat seed was used. These results were confirmed when in gel assays were performed. All three seed proteinaceous extracts had an optimum pH inhibition of 6.0. Thus, it is concluded that wild oat seed proteins are potentially good for detailed investigation in order to get a clear picture of its active compound/s and its structure-function relationship.