Piper guineense(Thonn.) as a Protectant of Melon (Citrullus vulgaris Schard) against Merchant beetle (Oryzaephilus mercator (Fauvel) (Coleoptera : Silvanidae): A Laboratory Evaluation
ABSTRACT: Laboratory experiments were conducted to assess the effectiveness of black pepper, Piper guineense (Thonn.) as a protectant of melon, Citrullus vulgaris Schard against fourth instar larvae of the Merchant beetle, Oryzaephilus mercator (Fauvel) in each of two
environments (aerated and airtight). In the aerated environment, the means of O. mercator emergence, were 19.84 +0.46, 9.49 + 0.90, 6.40 + 0.34, 3.46 + 1.25, 1.49 + 0.90, 0.00 + 0.00, and 0.00 +0.00, for the control, 0.25g, 0.5g, 0.75g, 1g, 2g, and 3g pepper 120g melon, respectively, while the corresponding means in the airtight environment were 18.42 + 1.06, 8.86 ±3.88, 4.93 ± 0.26, 2.78 ± 2.82, 1.09 ± 0.58, 0.00 ± 0.00, and 0.00 ±0.00.
Student-Newman-Keuls Procedure indicated that in both environments, all the six rates of black pepper significantly reduced O. mercator emergence compared with the control treatment. Total control was obtained at 2g pepper/20g melon and 3g pepper/20g melon
treatments in both environments. The LC50 and LC90 of black pepper against O. mercator were 0.27g and 0.9~g pepper 120g melon, respectively, in the aerated
environment and 0.30g and 0.93g pepper/20g melon, respectively, in the airtight environment. Thus the black pepper, which is readily available throughout the year in the West African region, relatively cheap, non-toxic, and amenable to safe handling by illiterate peasant farmers, provides a good alternative to synthetic insecticides in the control of O. mercator since resistance to most of these chemicals had been reported.