Submitted to: Molecular Ecology Notes
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2002
Publication Date: 10/14/2002
Citation: BON, M.C., HURARD, C., HOELMER, K.A., SHANOWER, T.G., MORRILL, W. GENETIC DEMARCATION OF THE NORTH AMERICAN WHEAT STEM SAWFLY POPULATIONS CEPHUS CINCTUS NORTON, (HYMENOPTERA: CEPHIDAE)N REVEALED BY MOLECULAR MARKERS. Molecular Ecology Notes. 2002. v. 5. p. 397-409. Interpretive Summary:
Technical Abstract: In North America, the wheat stem sawfly, Cephus cinctus Norton, and associated parasitoids were originally recovered from wild grasses ranging from California to Manitoba.This sawfly rapidly adapted to wheat, (Triticum aestivum L.), and is currently a chronic pest of economic importance in the northern Great Plains.Two species of parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck Hymenoptera: Braconidae), have followed sawflies from wild grasses into wheat.Parasitism levels vary significantly for unknown factors. Understanding the geographic structure of this species in the wheat growing regions may substantially enhance the monitoring of the biological control program. Wheat stem sawfly adults were collected at several sites across the Northern Great Plains (Montana, Idaho, North Dakota). Intraspecific variation in the species was examined using the mitochondrial cytochrome oxidase I gene. Sequence divergence of the 805 bp COI amplicon between wheat stem sawfly from North Dakota and Idaho, Southern Montana and Northern Montana populations is 0.99%. A phylogeographic pattern of genetic diversity appears to be emerging with a genetic demarcation zone that might be in Montana. Complete congruence observed between previous results obtained using RAPD markers and our results reinforces the hypothesis that wheat stem sawfly has evolved toward different developmental behaviours according to the locations that likely coincide with the susceptible phenological stages of winter wheat. This study will be expanded to include more individuals per population and also to investigate more populations in the northern Great Plains.