Effect of plant volatile oils in protecting stored cowpea Vigna unguiculata (L.) Walpers against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) infestation.

Adult Callosobruchus maculatus (F.) were introduced into cowpea seeds which were stored in containers with volatile oils derived from Mentha arvensis, M. piperata, M. spicata and Cymbopogon nardus. The numbers of eggs laid, adult mortality, adult emergence and subsequent seed damage were studied for four months. All oils significantly influenced all parameters (P<0.05) and results with different parameters were generally parallel. Significant differences for at least some time/parameters combinations indicated an order of potency of M. spicata>M. piperata>M. arvensis>C. nardus.