Effects of Excess Insecticide Application on Cowpea (Vigna unguiculata) Seeds by responses of Colonized Cowpea Weevil (Callosobruchus maculatus)

This study was designed to determine the effect of excess insecticide application on stored cowpea (Vigna unguiculata) seeds sourced from Lapai market, Niger State, Nigeria using appropriate standard techniques. The effect quantum was using cowpea weevil (Callosobruchus maculatus) as Biomarker. Result obtained show that lethal concentration of insecticide significantly (P < 0.05) affected duration of immature development, with highest concentration increasing the duration of larval development significantly. Larval and pupal mortality (11.20±1.24 and 67.20±4.65; 8.04±0.44 and 36.20±2.11 for negative control and highest treated concentration respectively) were significantly (P < 0.05) affected by increase in insecticide concentration. Mean temperature and relative humidity (28.77±1.2 and 35.88±5.14 respectively) of the immediate stored cowpea environment were within the ambient condition. Protein and Carbohydrate were the two proximate composition that varied significantly as a result of insecticide application. Cowpea weevil have shown a great potential of serving as a potential bio-markers of insecticide contamination of stored cowpea seeds in storage. Further research on similar and other biological effects of abused insecticide on colonizing weevil should be carried out in and outside laboratory condition.