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Insecticidal Potential of Two Indigenious Plant Extracts and Synthetic Dust on Control of Callosobruchus chinensis (L) in Pigeon Pea Seeds
Abstract
Synthetic pesticides have proven to be the most effective control agents against all pests of minor pulses. However, considering the drawbacks of pesticide residues in the seed quality, environmental pollution, and damage to natural enemies associated with synthetic pesticide use, integrated pest management schemes for pulses are being developed. The study evaluated the insecticidal potential of two indigenous plant extracts and synthetic dust on control of callosobruchus chinensis in pigeon pea seeds. Two botanicals: Eugenia aromatic and Piper guineese, were used in combination with synthetic dust at different treatment combinations for the control of Callosobruchus chinensis. The Callosobruchus chinensis used was derived from a colony originating from heavily invested pigeon pea seeds in the laboratory, while clean NSWCC-50 pigeon pea seeds were obtained from Institute of Agricultural Research and Training (IAR&T), Ibadan, Nigeria. The botanical plant extracts were obtained from a herbal store in Owerri. They were oven- dried at 60oC for 48hrs and grounded to a powder form in an electric mill. The synthetic dust (pirimiphos-methyl and permethrin) were used at a fixed application rate of 0.lg, while the botanical were varied at 0.02, 0.04, 0.06, 0.08, 0.10 g/ 20 seeds. Both the synthetic dust and the plant extracts were used singly and in combination. The mortality of Callosobruchus chinensis was monitored within the time intervals of 12, 24, 48 and 72hrs. The result showed that a sub-lethal dose of pirimiphos-metyl produced 100% adult mortality of Callosobruchus chinensis. The study also revealed that there is great potential in reducing the rate of application of synthetic organic insecticides by mixing with a sub-lethal dose of insecticidal materials. It is however, recommended that to maintain the optimum quality of pigeon pea seeds in storage, all possible combinations of low dosages of both the insecticidal plant powders and synthetic organic dusts should be tested so that the best mix can be determined.