Monitoring insect diversity and parasitism levels in alfalfa seed production fields in western Canada

• Author / Creator

  Reid, Michelle

• Alfalfa, Medicago sativa (L.) (Fabales: Fabaceae), is an excellent source of high protein feed for livestock. Canada is the second largest producer of alfalfa seed (4.2 M kg/year) in the world, with the vast majority of production concentrated in the province of Alberta. The productivity of these fields is threatened by an invasive insect, the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) as well as a myriad of other potential insect pests. Recently, insecticide resistance was confirmed in several alfalfa weevil populations in Alberta, and few other management options exist. Many natural enemies of alfalfa insect pests are present in Alberta, including biological control agents of alfalfa weevil, Bathyplectes curculionis (Thomson) (Hymenoptera: Ichneumonidae) and Oomyzus incertus (Ratzeburg) (Hymenoptera: Eulophidae); however, the distribution of these species and their parasitism levels are currently unknown. Here, we assessed the current diversity and distribution of insects in alfalfa seed production fields, with special emphasis on parasitism levels of B. curculionis and O. incertus throughout southern Alberta. A survey was conducted to collect insects, including alfalfa weevil larvae, from seed production fields in 2020 and 2021. During this survey, insect collections were taken from fields at three crop stages: bud, flower and seed, these insects were sorted to guild (pest of alfalfa or natural enemy of pests) and identified to genus and species. In addition, alfalfa weevil larval samples were collected weekly from the end of May to the beginning of July to assess the activity period of these parasitoids, finding parasitism activity throughout the month of June and into July. Parasitism levels based on the multiplex PCR assay were comparable to live rearing and ranged from 0-90% across sites. Assessing when and where these parasitoids occur, as well has how the two guilds interact will allow growers to better utilize these biological control agents and, ultimately, reduce spray applications.

• Subjects / Keywords

  • Agriculture
  • Biodiversity
  • Alfalfa
  • Parasitism

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-k7pt-b371

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.