Genetic diversity of Callosobruchus maculatus Fabricus (Cowpea weevil) populations in various agro‐ecological areas of five countries in West African sub‐region

Abstract

The cowpea (Vigna unguiculata (L) Walp) is a legume of African origin. It is source of very important nutritional needs like protein and vitamins for the developing countries especially countries of West Africa. The attack by the Bruchinae seedâ€beetle Callosobruchus maculatus (Fab) whose larvae develop in seeds causes losses ranging from 30 to over 80% of the harvest between 6 â€7months of storage. The objectives of this study were to identify the different haplotypes of the weevils’ West African subâ€region, to study genetic diversity in different agroâ€ecological zones and then highlight the phylogenetic affinities between the weevils from these different areas. In this study, we have analysed the sequences of the mitochondrial gene cytochrome b and 28S ribosomal gene in 75 individuals. 42 haplotypes for cytochrome b have been identified in three clades against 30 for the 28S divided into two clades. Individual haplotypes were mainly from the Guinean zone. Genetic distance and nucleotide diversity showed a trend of population structure of weevils between the different agroâ€ecological zones. This work is corroborated by low values of diversity within the zones and highly significant between them. Although Sudanian’ zone seemed not to confirm this view because of a relatively small percentage of alignment for individuals from Tenkodogo (Burkina Faso). The phylogenetic reconstructions have thus shown that gene flow was maintained even if it remained within narrow zones between agroâ€ecological zones for the populations of West African C. maculatus.