Study of relative susceptibility and amino acid species losses resulting from Sitophilus oryzae L. (Coleoptera: Curculionidae) infestation to various rice varieties

Abstract

Among the stored grain pests of rice, the Sitophilus oryzae is the most devastating one having the destructive potential of fouling about 50 gm of rice in just a span of three generations. It causes not only quantitative losses but also qualitative ones. The former can be ascertained by taking pre and post-infestation rates of a fixed number of rice grains infested by a fixed number of weevils and comparing it with the control. Qualitative changes one which involves loss of amino acid species could be ascertained by scanning the amino acid content of pre and post-infestation samples by double dimension paper chromatography. Different rice variety subjected to infestation underwent different degree of losses while in Shaktiman the weight loss was most pronounced (35.72%), the Pusa 2-21 suffered the least (23.72%). Kanak underwent moderate losses (27.84%). As far as loss of amino acid is concerned post infestation Shaktiman lost 6 amino acids of which one was the essential amino acid. Both kanak and Pusa 2-21 have had 13 amino acid before infestation but after infestation Pusa 2-21 losses four amino acid out of which three is essential where as Kanak losses three amino acids all are essential one.