Effect of some plant seeds protein extract on α-amylase activity and some biological parameters of cotton bollworm

In the present study, effect of seed protein extracts of Robinia pseudoacacia, Medicago sativa, Lens culinaris and Vica villosa were studied (in vitro and in vivo) on alpha-amylase activity of boll worm, Helicoverpa armigera (Hübner). Effect of 4 concentrations (14, 13.15, 10.05 and 9.7 μg) of protein extract of the mentioned plants showed the greatest inhibitory effect. The highest inhibition of the enzyme was observed under the influence of all four inhibitors at pH value equal to 9. Zymogram analysis in confirmation of enzyme quantification showed inhibition of alpha-amylase in reducing band thickness. At the highest concentration of alfalfa seed protein extract, 49% enzyme inhibition was observed. In the presence of acacia inhibitor at a concentration of 41 μg / ml, 76% of alpha-amylase activity was reduced. Alpha-amylase was assayed at different concentrations of lentil protein extract and a concentration-dependent inhibitory process was obtained at the highest concentration of 51% enzyme inhibition. Also, four different concentrations of hairy vetch inhibitor were measured with enzymatic extract and in the highest concentration of hairy vetch, 61% of enzyme inhibition was observed. Amylase activity in digestive lumen after the second larval instar in acacia treatment showed significant reduction. Total larval longevity in acacia treatment (49.03±1.12) had significantly longer life time in comparison with other treatments. Thus, the seed extract of R. pseudoacacia had high inhibitory activity for the α-amylase of this pest.