TOXIC AND REPELLENT EFFECTS OF THREE EDIBLE SPICE OILS ON CALLOSOBRUCHUS MACULATUS (F.) (COLEOPTERA: BRUCHIDAE) INFESTING STORED BAMBARA GROUNDNUT VIGNA SUBTERRANEA (L.) VERDCOURT

The insecticidal and repellent effects of clove (Syzgium aromaticuni), West African black pepper (WABP) (Piper guineense) and ginger (Zingiber officinale) oils were evaluated against the cowpea seed bruchid (Callosobruchus maculatus) infesting stored bambara groundnut under prevailing storage conditions in Ni­ geria. In the toxicity tests C. maculatus adults were exposed to 5 g of bambara groundnut seeds admixed with five dosages of each spice oil while in the repellency tests adult bruchids were introduced onto test arenas (filter paper discs) treated with different dosages o f each of the spice oils. Insecticidal spice oils were ranked in the order of decreasing toxicity as clove oil (LC.O =1.33 rng/5 g seed) > WABP oil (LC.O =1.59 mg/5 g) > ginger oil (LC.O = 7.08 mg/5 g). Significantly higher proportions of C. maculatus adults were repelled from filter paper discs treated with clove or WABP oil than from discs treated with ginger oil. At the dosage of 100-250 mg/ 30cm2, clove oil and WABP oil evoked class V repellency (80.1-100%) while ginger oil evoked classes IV (60.1- 80%) and V repellency.