Evaluation of Insecticidal Potential of Capsicum chinense Jacq. and Aframomum melegueta K. Schum. Against Trogoderma granarium Everts (Coleoptera: Dermestidae) in Groundnut

Abstract

The insecticidal potential of seed powders of Capsicum chinense Jacq. (Solanaceae) and Aframomum melegueta K. Schum. (Zingiberaceae) was tested against Trogoderma granarium (Coleoptera: Dermestidae) in the laboratory at (28±2)°C and 70%±5% relative humidity. The seed powders were tested at the rates of 0.0%, 0.5%, 1.0% and 1.5% (w/w) of groundnut seeds replicated three times. At the highest rate of treatment, C. chinense caused 56.7% and 76.8% larval mortality at 3 and 7 days post treatment (DPT) respectively while A. melegueta exerted 53.4% and 73.8% larval mortality at 3 and 7 DPT, respectively. Results showed that insecticidal potential of the seed powders against adult mortality of T. granarium and seed damage followed similar trend. The various rates of C. chinense seed powder performed better than A. melegueta seed powder in causing larval and adult mortality and in reducing seed damage. The activity of the seed powders on mortality of the insect, seed weight loss and seed damage were exposure time and rate dependent. A significant reduction (p<0.05) in seed weight loss and seed damage was recorded among the treatments and maximum reduction was observed in the seeds treated with the highest rate of C. chinense seed powder. Percentage seed damage significantly (p<0.05) decreased with increase in the rate of treatment while the highest seed weight loss and seed damage were obtained in the control. The study showed that C. chinense seed powder had higher activity against the test insect pest than A. melegueta seed powder. The two seed powders had high bio-activity against the insect and therefore could be used in formulating environment friendly plant-derived insecticide.