Synthesis of N alkyl chitosan and their impact on biology and physiology of fall armyworm, Spodoptera frugiperda

Abstract

Abstract A chitosan derivative, N-alkyl chitosan, was synthesized from crude chitosan, a marine waste product, by an alkylation process and it was characterized in FTIR and standardized its solubility, degree of deacetylation, and water binding capacity. It was evaluated for its toxicity, antifeedant effect, and impact on the growth, development, and physiology of S. frugiperda at different concentrations. N alkyl chitosan 5000 ppm recorded a maximum absolute antifeedant index of 85.96 percent in first instar larvae, after 72 hours of treatment. The highest mortality (Abbott’s corrected) was recorded when fed on N alky chitosan at 5000 ppm (77.44%). The median lethal concentration of N alkyl chitosan derivative was 3702.18 ppm with a median lethal time of 32.28 hours. The larval weight was reduced by 47.56 and 40.97 percent over the untreated check when S. frugiperda larvae fed on leaf treated with N alkyl chitosan at 5000 and 4000 ppm, respectively, throughout the larval period and also showed significant weight loss in pupal (15.83%) and adult (16.66%) stages, over the untreated check.