Extraction and Evaluation of the Effectiveness of Chitosan as Insecticides on the Immature Stages of the Saw-Toothed Grain Beetle Oryzaephilus Surinamensis L. (Coleoptera: Silvanidae)

Abstract

This study aimed to collect samples of amber rice infected with the saw-toothed grain beetle from local markets in Kirkuk city during 13 December 2023 to 25 April 2024, and the experiments were conducted in the laboratories of the College of Education for Pure Sciences at Kirkuk University from February to April 2024. The toxic effects of chitosan were studied at three different concentrations: 0.5, 1.0, and 1.5 ppm on the immature stages of the saw-toothed grain beetle. The substance exhibited significant effects on the immature stages of the insect , recording the shortest egg incubation period with an average of 8.17 days, while chitosan treatment showed a significantly longer periods of 9.66, 11.69, and 14.00 days for concentrations of 0.5, 1.0, and 1.5 ppm respectively. The larval stage duration had a direct proportionality with the chitosan concentrations, where the 1.5 ppm concentration registered the longest larval period of 22.00 days, as opposed to the control which recorded the shortest period of 13.56 days, and the 0.5 and 1.0 ppm concentrations recorded durations of 17.19 and 19.66 days respectively. In the pupal stage, significant differences were found when the chitosan concentration was increased, with the control treatment having the shortest pupal stage duration of 4.33 days; a direct correlation was found between the concentrations and the pupal stage duration, which decreased to 6.00, 7.59, and 9.07 days for the 0.5, 1.0, and 1.5 ppm concentrations, respectively.