title: Effect of Wheat Cultivars and Blends on the Oviposition and Larval Mortality of Cephus cinctus (Hymenoptera: Cephidae) and Parasitism by Bracon cephi (Hymenoptera: Braconidae).
abstract: The wheat stem sawfly (Cephus cinctus Norton) is a major historical pest of wheat in the northern Great Plains of North America. The insect spends most of its life as a larva protected inside grass stems so that its management has relied on strategies other than insecticides. We conducted a study in southern Alberta from 2006-2009 to assess the effects of wheat species, cultivar, seeding rate, and blending a resistant and a vulnerable cultivar, on oviposition, larval infestation, and cutting damage. The mortality caused by its primary parasitoid, Bracon cephi (Gahan), was also assessed to investigate the potential benefit of cultivar blends to enhance sawfly biological control. Sawfly laid fewer eggs on plants of the durum cultivar 'AC Avonlea' and on those of the solid-stemmed cultivar 'Lillian' compared to plants of the hollow-stemmed cultivar 'CDC Go.' Larval establishments (infestation) followed a similar pattern to that of oviposition. At these locations there was low cutting damage in most years and to a large extent this was due to mortality inflicted by the parasitoid Bracon cephi (40-60%). However, the remaining mortality was attributed to other factors and host, particularly the inclusion of the solid-stemmed cultivar. Direct and indirect factors likely affected the success of the parasitoid in the crop monocultures and blends, and these mechanisms require further research.
authors.affiliation: Agriculture and Agri-Food Canada, Science and Technology Branch, 5403-1st Ave., South, Lethbridge, Alberta, Canada T1J 4B1 (hector.carcamo@agr.gc.ca; brian.beres@agr.gc.ca; tracy.larson@agr.gc.ca; cassidy.klima@agr.gc.ca), hector.carcamo@agr.gc.ca.
authors.forename: H A
authors.initials: HA
authors.lastname: Cárcamo
authors.affiliation: Agriculture and Agri-Food Canada, Science and Technology Branch, 5403-1st Ave., South, Lethbridge, Alberta, Canada T1J 4B1 (hector.carcamo@agr.gc.ca; brian.beres@agr.gc.ca; tracy.larson@agr.gc.ca; cassidy.klima@agr.gc.ca).
authors.forename: B L
authors.initials: BL
authors.lastname: Beres
authors.affiliation: Agriculture and Agri-Food Canada, Science and Technology Branch, 5403-1st Ave., South, Lethbridge, Alberta, Canada T1J 4B1 (hector.carcamo@agr.gc.ca; brian.beres@agr.gc.ca; tracy.larson@agr.gc.ca; cassidy.klima@agr.gc.ca).
authors.forename: T R
authors.initials: TR
authors.lastname: Larson
authors.affiliation: Agriculture and Agri-Food Canada, Science and Technology Branch, 5403-1st Ave., South, Lethbridge, Alberta, Canada T1J 4B1 (hector.carcamo@agr.gc.ca; brian.beres@agr.gc.ca; tracy.larson@agr.gc.ca; cassidy.klima@agr.gc.ca).
authors.forename: C L
authors.initials: CL
authors.lastname: Klima
authors.affiliation: Institute of Forest Management and Protection, Inner Mongolia Academy of Forestry, Hohhot, Inner Mongolia 010010, China (wuxiuhua73@hotmail.com).
authors.forename: X-H
authors.initials: XH
authors.lastname: Wu
mesh_terms: D000416:Alberta; D000818:Animals; D060434:Herbivory; D006927:Hymenoptera / Q000254:growth & development / Q000469:parasitology* / Q000502:physiology*; D007814:Larva / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D008136:Longevity; D010058:Oviposition; D014908:Triticum / Q000254:growth & development / Q000502:physiology*
keywords: Cephidae; biological control; host plant resistance; parasitoid population; tritrophic interaction