Submitted to: International Symposium on Biological Control of Arthropods
Publication Type: Abstract only
Publication Acceptance Date: 3/12/2005
Publication Date: 9/12/2005
Citation: Bon, M., Shanower, T.G., Morrill, W., Hoelmer, K.A., Martin, J. 2005. Phylogeography and genetic structure of the invasive wheat stem sawfly, Cephus cinctus Norton, (Hymenoptera: Cephidae) in North America: New insights into the biological control management of this pest. International Symposium on Biological Control of Arthropods. Poster. Interpretive Summary:
Technical Abstract: The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae) was originally recovered from wild grasses but has become a chronic pest of wheat in the northern region of the North American Great Plains. Effective and economical pest management practices remain elusive, therefore biological control options are being investigated. It is important to clarify the geographical history and population structure of this species so that source areas for biological control agents can be more accurately located. In addition, this study may settle a debate about the origin of C. cinctus: is it synonymous with an Asian species and accidentally introduced or is it indigenous to North America? Due to the lack of Asian specimens, we began our study with North American samples, using cytochrome oxidase subunit I mitochondrial DNA genealogies obtained from 57 North American populations to assess the extent of the phylogeographic structure in this morphologically monotypic insect. Mitochondrial sequences uncovered 25 haplotypes, thirteen of which were present in Montana, five in Canada (Alberta and Saskatchewan), and the remaining ones in Wyoming, Nebraska, North Dakota, and Idaho. The results showed highest nucleotide diversity in Montana and absence of structuring of mtDNA variation within the wheat continuum that is represented by these two provinces of Canada and Montana. The phylogeographic pattern observed did not reflect the population bottleneck that likely would have occurred during a single recent colonization event. However, the present analysis is providing multiple inferences on the reconstruction of the invasion routes and origin of the pest which will be discussed, and a further refinement of the biological control program proposed.