Comparative effectiveness of some plant materials on the mortality of cowpea weevil, Callosobruchus maculatus (Fab.) (COLEOPTERA: BRUCHIDAE) in stored cowpea

Abstract

Studies were carried out in the laboratory to evaluate the potential insecticidal efficiency of the powdered form of some locally available plant materials relative to a conventional storage chemical, Actellic 2% dust (Pirimiphos-methyl) on stored cowpea against the cowpea bruchid. Ten plant materials selected based on their reported active ingredients or one form of folk medical use or the other were used. Each of the materials were tested at four rates (2.5g, 5.0g, 10.0g/100g seed including the control, i.e., 0.0g). Actellic dust was applied at the rate of 1.0g, 2.0g and 3.0g/100g seed. Data on the effects of the materials on mortality of C. maculatus were collected at 24 hours, 48 hours and 7 days over a seven-month period. The ten plant materials generally performed better than the control. The interactive effect of the plant materials was found to be dose-related. However, only Piper guineense, Moringa oleifera and Ocimun gratissimum, in that order, performed comparably well with Actellic dust. Actellic dust at the lowest rate inflicted adult mortality of 90-100% in the first 48 hours after treatment whereas Piper guineense at the lowest rate (2.5g/100g seed) inflicted mortality of up to 90.0% in 48 hours. Moringa oleifera at the medium rate (5.0g/100g seed) and Ocimum gratissimum at the highest rate (10.0g/100.0g seed) gave mortality of 76.7% and 60.0% in 48 hours, respectively.