Phylogenetic Analyses and a Method for Rapid Molecular Diagnosis of Two Sunflower Seed Weevils (Coleoptera: Curculionidae)

The red sunflower seed weevil, Smicronyx fulvus LeConte, and gray sunflower seed weevil, Smicronyx sordidus LeConte (Coleoptera: Curculionidae), are among the most important seed pests of cultivated sunflowers, Helianthus annuus L., in the northern Great Plains. A portion of 18S ribosomal DNA (18S rDNA) sequence from specimens of 31 populations of the morphologically similar species that were collected across a wide geographic region of the United States showed a consistent separation of the two species. The restriction endonuclease HaeII digests the piece of 18S rDNA in only one of the two species, and this restriction fragment-length polymorphism can be used for species diagnosis. Phylogenetic analysis for species of four tribes of the weevil subfamily Erirhininae showed that the sunflower seed weevil tribe, Smicronychini, is monophyletic.