Inhibitory effect of wheat seed cultivars extract s on digestive alpha amylase activity of Colorado potato beetle

Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chyrsomelidae) is a key pest of potato worldwide. Given the adverse effect of the pesticides applied against this pest, alternative method for the pest control is unavoidable. Thus, the aim of the current study was to study the effect of wheat cultivars proteinaceous extract against the beetle α-amylase. The enzyme extraction from the beetle and proteinaceous extract from the wheat seeds were done using distilled water and 0.1 M NaCl, respectively. The results showed that proteinaceous extracts of wheat seeds have great ability to inhibit Colorado potato beetle α-amylase. Enzyme assays in the presence of five concentrations of Aflak and MV-17 wheat seed cultivars showed a dose dependant manner of enzyme inhibition. Remaining activity of the enzyme when concentrations of 17, 8.5, 4.25, 2.125 and 1.06 µg protein of extract were used was 18, 30, 45.74, 48.74, 58.32, and 60.72%, respectively compared to control. The results showed that Aflak cultivar is less effective in the enzyme inhibition than MV-17 cultivar. Studying the effect of pHs on the inhibition showed that the greatest inhibition in the presence of the highest amount of inhibitor was observed at pH 5. Gel assays showed that bands intensity was decreased in the presence of different concentrations of both cultivars extracts and the changes of the bands intensities was dose dependant.