Distribution of three weevil species in the various growth stages and residues of plantains (<i>Musa</i>spp) in Littoral Region of Cameroon

Abstract

Many people in the rural and semi-urban areas in the tropics depend on plantains and bananas as a staple food and as source of income. Bio-ecological studies such as quantifying insect pest numbers within-plants and with-in residues will help to reduce the amount of insecticides applied in plantations or farms. The distribution of three weevil species with respect to plantain growth stages and pre-/postharvest residues was studied in a researcher-managed and a farmer-managed farm. Adult weevil species were counted from the following growth stages; suckers, pre-flowered, flowered, and bunched plants; as well as from these residues; desuckers, pseudo stem stumps, and cut pseudostems lying horizontally on the ground. Although Cosmopolites sordidus is widely reported as the most economically important insect on bananas/plantains, there were significantly more Polytusmellerborgi compared to C. sordidus and Metamasiushemipterus (very rare). In both farms, highest numbers of C. sordidus were found on pseudostemstumps as well as on bunched plants. In all the growth stages, numbers of the different weevil species were not significantly different in both farms. Also, for the residues, except for desuckers, all weevil species were similar in both farms. We proposed therefore that for any effective management of C. sordidus, application of management techniques that will significantly reduce adult numbers should focus on harvested stumps and bunched plants.

Keywords: Coleoptera, Cucurlionidae, Insect, Pest management