Molecular differentiation of Bathyplectes anurus and Bathyplectes curculionis, parasitoids of alfalfa weevil (Hypera postica) in Virginia

Bathyplectes anurus and B. curculionis (Hymenoptera: Ichneumonidae) are specialist parasitoids introduced to the United States for classical biological control of alfalfa weevil, Hypera postica (Coleoptera: Curculionidae).  Both species of Bathyplectes are established throughout much of the United States, including in Virginia, and often coexist within fields and regions.  Adults of the two species are nearly identical morphologically and thus difficult to differentiate.  Identification to species is usually achieved by sight recognition of the parasitoid cocoons, which evince characteristics unique to each species.  Molecular taxonomy provides another means of identifying and differentiating these two species of Bathyplectes.  The purpose of this study was to derive sequences of one or more gene regions by which B. anurus and B. curculionis specimens can be molecularly identified.  Genomic DNA was extracted from Bathyplectes cocoons and adults collected from seven counties in three geographic regions of Virginia and from specimens collected in Boulder County and Pueblo County, Colorado.  Sequences were derived for a portion of the 28S rDNA gene (approximately 625 base pairs) and a portion of the mitochondrial CO1 gene (approximately 620 base pairs).  Sequences obtained from Colorado specimens of each species matched 99% to 100% to sequences obtained from Virginia specimens of the same species, providing species-level consensus.  Alignment of the species-level consensus sequences using SeqMan Pro resulted in a 96% match for the 28S rDNA gene and an 89% match for the CO1 gene, which indicates that B. anurus and B. curculionis can be differentiated by these gene sequences.