When DNA sequences and microsatellites loci tell the story of field groundnut infestation by Caryedon serratus Ol. (Coleoptera, Chrysomelidae, Bruchinae)

Abstract

The first infestations of stored groundnuts by the seed-beetle Caryedon serratus were reported in this country at the turn of the 20th century. This bruchid has a wide distribution in Africa, from Senegal to South Africa and in southern Asia. Native hosts of C. serratus in Senegal include Bauhinia rufescens, Cassia sieberiana, Piliostigma reticulatum and Tamarindus indica, all of which belong to the legume subfamily Caesalpinioideae. Molecular marker, DNA sequences and microsatellites loci polymorphism were used to investigate the mechanisms of first groundnut infestation by C. serratus. Sequence analysis of ribosomal DNA nuclear (ITS1) and mitochondrial coding DNA (Cytochrome b) reveal several biotypes in Senegal, with restricted past and/or present gene flow between each other. Samples typically clustered according to host plant, except for groundnut and P. reticulatum, which clustered together. Polymorphic microsatellites loci confirm the allelic proximity between P. reticulatum and groundnut C. serratus. These strains, genetically very close, begin however to diverge but the number of migrants between them keeps relatively important. Historical hypothesis of the first groundnut infestation in West Africa is also debated in this study. Key words: Groundnut, Caryedon serratus, Piliostigma reticulatum, groundnut, infestation, ITS, Cyt. B, DNA sequences, microsatellite loci.