The toxicity and repellent effects of steam distilled oils of Ocimum suave, Piper guineese, Syzgium aromaticum and Xylopia aethiopica were evaluated against the cowpea bruchid (Callosobrochus maculatus) infesting stored cowpea seeds under prevailing storage conditions in middle belt of Nigeria. In toxicity test C. maculatus adults were exposed to 10 g of cowpea seeds (Vigna unguiculate) admixed with five dosages of each oil. While in the repellency tests adult bruchids were introduced onto test arenas (filter paper discs) treated with different dosages of each of the oil. Insecticidal oil were ranked in the order of decreasing toxicity as Syzgium aromaticum oil (LC50 = < 0.1 mg/10 g seed) > Xylopia aethopica oil (LC50 = 0.485 mg/10 g seed > Piper guineese oil (LC50 = 0.510 mg/100 g seed) > Ocimum shave oil (LC50 0.660 mg/10 g seed). Significantly higher proportion of C. maculates adults were repelled from filter paper discs treated with all plant oils with average means repellent order of 60.24, 77.87, 80.23 and 86.66% for Xylopia aethiopica, Piper guineese, Syzguim aromaticum and Ocimum suare, respectively.
A. Olonisakin, M.O. Oladimeji and L. Lajide , 2006. Bioactivity of Steam Distilled Oils Against the Cowpea Bruchid, Callosobrochusmaculates (F) Infesting Stored Cowpea Seeds. Pakistan Journal of Biological Sciences, 9: 1271-1275.