Effects of some plants seed extracts on Helicoverpa armigera H�bner (Lepidoptera: Noctuidae) midgut protease activity

Abstract : 

Helicoverpa armigera is one of the most important pests of crops, such as cotton, cereals and vegetables. Using plant derived enzyme inhibitors in transgenic plants is one of the safe methods in IPM programs. In this study protease inhibitory activity of some plants seed extracts from poaceae and fabaceae family were studied. Insects reared in controlled condition and the last larval instars alimentary canal were used in enzymatic assays. The crude seed extracts were subjected for ammonium sulfate precipitation. The seed extracts of six plants were fractionated into four fractions (0-30 %, 30-50, 50-70 and 70-80%). The percentage of inhibition to cotton bollworm midgut protease activity obtained in crude and each protein fraction of ammonium sulfate. Proteolytic activity of midgut enzyme extracts was evaluated using the azocasein as substrate. The results revealed that seed extracts of Phasaeolus vulgaris and Cicer arietinum are potentially effective in inhibiting the proteolytic activity of cotton bollworm (54.5 and 53.2% respectively). Also total extracts of Triticum aestivum, Hordeum vuIgare, Zea mays, and sophora alopecuroides inhibited HGP activity by 17.7, 18.74, 20.62 and 29.31% respectively. Results revealed that the F1 fraction protein of all studied plants showed less than 20% inhibitory activity against HGP, and the F2 and F3 fraction exhibited the same inhibitory activity in the range of 10-20% in poaceae species. The legume plants especially in F1, F2 and F3 fractions exhibited near 15-50% inhibitory activity on HGP. In over all, among studied plants, Z. mays, P. vulgaris and C. arietinum have strong inhibitory activity in compare with others

Keyword : 

Inhibitory activity, poacea, fabacea, azocasein, ammonium sulfate, cotton bollworm

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