INSECTICIDAL EFFICACY OF THREE EDIBLE PLANT PRODUCT OILS AGAINST THE COWPEA BRUCHID, Callosobruchus maculatus (FAB.)
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Abstract
Three edible plant product oils, West African Black Pepper (WABP) Piper guineense Schum and Thonn; Clov* Syzgium aromaticum (L) Merril and Percy; Ethiopian pepper oil, Xylopia aethiopica (Dum) A. Rich, were studie_ for their effectiveness in suppressing or deterring oviposition, egg mortality and progeny emergence against ths cowpea bruchid, Callosobruchus maculatus (F) in the laboratory under ambient temperature and relative humidity The experiment was carried out as treatment before infestation CTBI) and treatment after infestation (TAI) on cowp^ seeds infested with cowpea bruchids. The edible plant product oil (EPPO) was used at the rate of0.25,0.5,0.75 aru 1.00 mg/10 g of cowpea seeds against cowpea bruchid C. maculatus. The TBI experiment showed that the entire plan product oil significantly (P<0.05) reduced oviposition by C. maculatus when compared with oviposition in the control treatments. Clove and WABP oil at the highest dosage rate of 1.00 mg completely deterred oviposition by Or adult C. maculatus and hence no adults emerged in the treatments. WABP oil completely deterred F2 adui emergence ai the dosage rates of 0.5 and 0.75; and clove oil deterred adult emergence of the F2 generation at the dosagrate of 0.75 mg. Ethiopian pepper oil was generally found to be less effective than clove and WABP when applied a. treatment before infestation. In the TAI the three essential oils significantly (P<0.05) reduced the percentage ofC maculatus adults that emerged. Egg mortalities were highest in all the treatments when compared with the contro and were statistically significant. No adult emerged in cowpea seeds treated with WABP and Ethiopian pepper oils a the rate of 1.00 mg/10 g seeds. The potential effectiveness of all the three edible plant product oil implied that store t cow pea seeds could be adequately protected against Callosobruchus maculatus; thus reducing their infestation am damage on cow pea seeds.