Toxicity and Sub-lethal effect of essential oils of Eugenia aromatica and Piper guineense on cowpea seed beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae)

Abstract

Under laboratory conditions (28 ± 3 oC and 65 ± 5% relative humidity) in Akure, Nigeria, essential oils of Eugenia aromatica and Piper guineense were evaluated for their toxicity and sub-lethal effect on cowpea seed beetle Callosobruchus maculatus (F.). The rate of application 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5ml per 20g of seed was tested. The mating propensity of males and females of C. maculatus after exposure to 0.05 and 0.4ml of the essential oils of both plants were also investigated. The results showed that the lowest dose of application of 0.05ml of the essential oils of P. guineense and E. aromatica was observed to cause significant increase in oviposition with up to 370 eggs laid and eclosion of 273 adults in C. maculatus. The lowest dose of the essential oils of P. guineense and E. aromatica was also observed to cause significant increased propensity to mate in males and females C. maculatus.