Rosemarie De Clerck-Floate, Ph.D.

Image Rosemarie De Clerck-Floate
Research Scientist - Weed Biological Control

Research on:

- Biological control of weeds

- Plant-insect interactions

- Insect and plant ecology


Current research and/or projects

  • Effects of soil moisture and nitrogen (climate change) on efficacy of weed biological control

  • Development of release strategies for predictable establishment and impact of weed biocontrol agents

  • Development of methods for biocontrol agent mass-production

  • Assessment of biological control safety and efficacy via studies of insect-plant ecological and evolutionary associations, insect and plant behaviour, insect impact on plant individuals and populations

Research and/or project statements

Biological control is a valuable tool in the mitigation of agricultural and environmental impacts from pest threats such as weeds. When effective, the strategy provides a sustainable, long-term and low-cost solution to pest management, especially in areas where chemical control may be unfeasible for economic and/or environmental reasons (e.g., weed control on native rangelands). Canada is seen as a world leader in the discovery, development and safe use of biological control agents for weeds, and since the AAFC program’s initiation in 1951, has produced several notable successes. Our program partners with regional governments, industry (cattle producers), academia, and international experts (e.g. CABI) in the assessment, release, and knowledge development for new biocontrol agents against emerging weed problems in Canada.

Professional activities / interests

  • Adjunct Professor, University of British Columbia - Okanagan

  • Adjunct Professor, University of Lethbridge

  • President, Entomological Society of Canada (2013)

  • Member, AAFC National Containment, Biosafety and Biosecurity Committee

  • Member, AAFC Biological Control Working Group

  • Student training

  • Science and art collaborations

Education and awards

  • Ph.D. (Botany/Entomology) – Northern Arizona University

  • M.Sc. (Biology) - University of Saskatchewan

  • B.Sc. (Biology) – Laurentian University

  • Federal Government 5-NR Science Award for Leaders in Sustainable Development (with R. Bourchier )for Weed Biocontrol Research 2001

International experience and/or work

  • Scientific Advisor – International weed biological control projects (e.g. toadflax, houndstongue, hawkweeds).

  • Transfer of Work (weed biological control)– CSIRO Brisbane, Australia (2004 – 2005)

Key publications

  1. Moffat, C.E., R.S. Bourchier, R.A. De Clerck-Floate, P.G. Mason, and D.J. Ensing. 2021. How do we know biocontrol agents are safe? An overview of the Canadian research and regulatory process for new biocontrol agents. British Columbia Invasive Species Council. Invasives 2021 Conference (virtual). 9 Februrary, 2021.

    2021 - View publication details

  2. Ensing, D.J., R. Bourchier, R. De Clerck-Floate, T.D. Nelson, V. Miller, S. Turner, C.E. Moffat. 2020. Classical biological control leads to long term declines in the rangeland invasive spotted knapweed. Entomological Society of America (virtual), 16-19 November, 2020.

    2020 - View publication details

  3. Ensing, D.J., T.D. Nelson, R. Bourchier, R. De Clerck-Floate, V. Miller, S. Turner, C.E. Moffat. 2020. Contemporary ecology of historical weed biological control programs: Re-evaluating spotted knapweed biocontrol in BC. Entomological Society of British Columbia (virtual), 26-28 October, 2020.

    2020 - View publication details

  4. De Clerck-Floate, R. 2019. Weevils from Serbia show promise in yellow toadflax biological control in Canada. Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada. Catalogue No. A22-631/2019E-PDF, ISBN No.978-0-660-32854-6, AAFC No. 12990E. 4 pp.

    2019 - View publication details

  5. Toševski, I., Sing, S.E., De Clerck-Floate, R., McClay, A., Weaver, D.K., Schwarzländer, M., Krstić, O., Jović, J., Gassmann, A. (2018). Twenty-five years after: post-introduction association of Mecinus janthinus s.l. with invasive host toadflaxes Linaria vulgaris and Linaria dalmatica in North America, 173(1), 16-34.

    2018 - View publication details

  6. Moffat, C.E., Ensing, D.J., Gaskin, J.F., De Clerck-Floate, R.A., Pither, J. (2015). Morphology delimits more species than molecular genetic clusters of invasive Pilosella, 102(7), 1145-1159.

    2015 - View publication details

  7. Catton, H.A., Lalonde, R.G., De Clerck-Floate, R.A. (2014). Differential host-finding abilities by a weed biocontrol insect create within-patch spatial refuges for nontarget plants, 43(5), 1333-1344.

    2014 - View publication details

  8. Gassmann, A., De Clerck-Floate, R., Sing, S., Toševski, I., Mitrović, M., Krstić, O. (2014). Biology and host specificity of Rhinusa pilosa, a recommended biological control agent of Linaria vulgaris, 59(4), 473-483.

    2014 - View publication details

  9. Moffat, C.E., Lalonde, R.G., Ensing, D.J., De Clerck-Floate, R.A., Grosskopf-Lachat, G., Pither, J. (2013). Frequency-dependent host species use by a candidate biological control insect within its native European range, 67(3), 498-508.

    2013 - View publication details

  10. Barnewall, E.C., de Clerck-Floate, R.A. (2012). A preliminary histological investigation of gall induction in an unconventional galling system, 6(3), 449-459.

    2012 - View publication details

  11. De Clerck-Floate, R.A., Saunders, P., Floate, K.D. (2012). Release and recapture of three insect species test the efficacy of trap method and air flow in insect containment, 144(4), 609-616.

    2012 - View publication details

  12. Julien, M.H., Xu, C.Y., Bourne, A., Gellender, M., De Clerck-Floate, R. (2012). Determining the growth responses of Phyla canescens to shoot and root damage as a platform to better-informed weed-management decisions, 60(4), 310-318.

    2012 - View publication details

  13. Van Hezewijk, B.H., Bourchier, R.S., De Clerck-Floate, R.A. (2010). Regional-scale impact of the weed biocontrol agent Mecinus janthinus on Dalmatian toadflax (Linaria dalmatica), 55(3), 197-202.

    2010 - View publication details

  14. Smith, E.G., De Clerck-Floate, R.A., Van Hezewijk, B.H., Moyer, J.R., Pavlik, E. (2009). Costs of mass-producing the root weevil, Mogulones cruciger, a biological control agent for houndstongue (Cynoglossum officinale L.), 48(3), 281-286.

    2009 - View publication details

  15. de Clerck-Floate, R., Wikeem, B. (2009). Influence of release size on establishment and impact of a root weevil for the biocontrol of houndstongue (Cynoglossum officinale), 19(2), 169-183.

    2009 - View publication details

  16. Andreas, J.E., Schwarzländer, M., De Clerck-Floate, R. (2008). The occurrence and potential relevance of post-release, nontarget attack by Mogulones cruciger, a biocontrol agent for Cynoglossum officinale in Canada, 46(3), 304-311.

    2008 - View publication details

  17. Van Hezewijk, B.H., De Clerck-Floate, R.A., Moyer, J.R. (2008). Effect of nitrogen on the preference and performance of a biological control agent for an invasive plant, 46(3), 332-340.

    2008 - View publication details

Research facility

5403 1st Avenue South
Lethbridge, AB T1J 4B1


  • Member, Entomological Society of Canada

  • Member, Entomological Society of Alberta

  • Member, Canadian Botanical Association

  • Member, Entomological Society of America

  • Member, Canadian Society of Ecology and Evolution