Genetic Distribution of the Cowpea (Vigna Unguiculata (L.) Walp) Bruchid (Callosobruchus Maculatus F., Coleoptera, Bruchidae) Populations in Different Agro-Ecological Areas of West Africa

Cowpea [(Vigna unguiculata L.) Walp. (Fabaceae)] is the most important food legume grown throughout West Africa. The seeds of this legume protein source are the least expensive for most African populations. However, cowpea production is severely limited by the losses (60-70%) caused by Callosobruchus maculatus F. (Coleoptera: Bruchidae). Whereas many studies have been devoted to the ecology of these bruchids and allowed to distinguish physiotypes and morphotypes, few studies have been conducted on the spatial and temporal structuring of populations of the weevil and migration patterns between agro-ecological areas. By using molecular data; (a combined set of a mitochondrial and ribosomal genes), this study aims to identify genetic diversity and phylogenetic affinities of allopatric C. maculatus populations within the West Africa subregion. Climate influence (Agro-ecological conditions) was also tested. The results reveal several ecotypes circulate in the West Africa sub-region. Among samples, the genetic distances measured on the total alignment of CytB + 28S (852 bp) ranged between 0 and 0.047 and show clearly fall in three classes. The phylogenetic reconstructions show clearly that the genetic structure of the C. maculatus populations is strongly influenced by the agro-ecological zone.