University of Alberta Mechanisms of cabbage seedpod weevil, Ceutorhynchus obstrictus , resistance associated with novel germplasm derived from Sinapis alba x Brassica napus by James Allen Tansey A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Science Department of Agricultural, Food and Nutritional Sciences ©James Allen Tansey Fall, 2009 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission. University of Alberta Faculty of Graduate Studies and Research The undersigned certify that they have read, and recommend to the Faculty of Graduate Studies and Research for acceptance, a thesis entitled ‘Mechanisms of cabbage seedpod weevil, Ceutorhynchus obstrictus resistance associated with novel germplasm derived from Sinapis alba x Brassica napus ’ submitted by James A. Tansey in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Agricultural, Food and Nutritional Science. Examining Committee Dr. Lloyd M. Dosdall, Agricultural, Food and Nutritional Science Dr. Andrew Keddie, Biological Sciences Dr. Maya Evenden, Biological Sciences Dr. Habibur Rahman, Agricultural, Food and Nutritional Science Dr. Robert J. Lamb, Research Scientist, Cereal Research Centre, Agriculture and Agri-Food Canada. Winnipeg, Manitoba; Adjunct Professor, University of Manitoba, Entomology Abstract Abstract The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae), is an important pest of brassicaceous oilseed crops, especially canola ( Brassica napus L. and Brassica rapa L.) in North America and Europe. Application of foliar insecticide is the only method currently employed to control C. obstrictus populations; because this approach is environmentally unsustainable, alternatives including host plant resistance have been explored. White mustard, Sinapis alba L., is resistant to C. obstrictus and was chosen as a potential source of resistance for B. napus oilseed. Interspecific crosses of S. alba x B. napus have produced several lines that are resistant to C. obstrictus feeding and oviposition and yield fewer, lighter-weight weevil larvae that take longer to develop. I investigated potential mechanisms of this resistance, including assessing differences in visual and olfactory cues among resistant and susceptible genotypes, and antixenosis and antibiosis. Determining effects of visual cues associated with host plant resistance required investigation of weevil vision. Deployment strategies for resistant germplasm were assessed to evaluate incorporation of susceptible refugia to promote long-term durability of resistance traits. Results reported in Chapter 2 indicate that the C. obstrictus visual system is apparently trichromatic and incorporates receptors with response maxima near 350, 450, and 550 nm. Modelling indicated that UV light alone reduced weevil responses but the interaction of yellow and UV light increased responses at a threshold reflectance level of UV. Results reported in Chapter 3 indicated that Abstract differences in yellow and UV reflectance among host plant flowers influence host selection in C. obstrictus . Results described in Chapter 4 determine differential attraction to the odours of S. alba and B. napus and among resistant and susceptible accessions. Inferences of the identities of glucosinolates found in varying amounts among susceptible and resistant genotypes suggested that 2- phenylethyl glucosinolate influenced attractiveness. Results described in Chapter 5 indicate differences in adult feeding and oviposition preferences among resistant and susceptible genotypes. Oocyte development, larval biomass and larval development time varied among weevils feeding on resistant and susceptible genotypes. Based on results of Chapter 4, 1-methoxy-3-indolylmethyl glucosinolate was implicated as contributing to antixenosis and antibiosis resistance. Results reported in Chapter 6 describe effects of mixed plots of resistant and susceptible genotypes on weevil spatial distribution and oviposition. These results are consistent with associational resistance and attributed to reduced apparency of susceptible plants in mixtures and antixenosis resistance associated with resistant germplasm. Acknowledgements Acknowledgements I would like to first thank Drs. Lloyd Dosdall and Andrew Keddie for taking me on as a student and providing an opportunity and resources for me to develop my research skills and further my interest in insect-plant interactions. Dr. Maya Evenden was also a member of my supervisory committee and integral to the successful completion of this project. My interactions with my supervisory committee were always positive and I am most grateful for them. Their expert advice, helpful comments and willingness to let me tap their great knowledge of subjects applicable and peripheral to this project and relevant to my growth as an entomologist and researcher were invaluable. Sincere thanks to Drs. Laima S. Kott, Scott D. Noble and Ron S. Fletcher for their collaborations. Without the hard work of the field and laboratory crews in Lethbridge and Edmonton, the scale of this project would have been greatly diminished. I must thank (in alphabetical order) Ross Adams, Nancy Cowle, Matt Fisher, Brett Hoffman, Jordana Hudak, Christina Gretzinger, Michael Gretzinger, Analea Mauro, Cameron Stevenson, Crystal Tebbie, Matt Treadwell and Nate Vos for their capable technical assistance at all times and for their patience with occasional long hours in harsh conditions. I would also like to sincerely thank Dr. Héctor Cárcamo of Agriculture and Agri-Food Canada, Lethbridge Research Centre for allowing us access to his lab and to exceptional facilities within the Centre. Other notable members of Agriculture and Agri-Food Canada, Lethbridge who have provided indispensible advice and assistance include Dr. Kevin Floate, Mr. Tom Kveder and Mr. Daniel Ethier. Acknowledgements My parents, Richard ‘Dick’ Tansey and Suzanne Lavallée are ultimately responsible for my participation in this project and they, and my brother Paul Tansey and extended family and friends deserve great credit for their support of this and all of my endeavours. Special thanks go to Jennifer Kranabetter. Long summers away from home made for good work but were never my favourite part of this project. Thanks for your patience, interest, support and sense of humour. Thanks to Rollie, Mary, Jeff and Paul Lavallée, Carmen Hankinson, Dale Hrdlicka, Judy Tansey, Joanne Nordmark Tansey, Yolande Lavallée and Monty Schneider, Mitch, Laura and Mark Lavallée, Leslie Hankinson and Susanne Schultz, Jennifer Hankinson Owen and Darren Owen, Rob and Liz Kranabetter, Donna Tansey (and the jars of grasshoppers), and Terry Sargent. Thanks too to Roy B. Malloy, Ethel Savard, and Tika and Oscar Kranabetter. I would also like to thank the University of Alberta and, in particular, the Department of Agricultural, Food and Nutritional Sciences for providing a stimulating workplace and professional home for myself and this project. I learned much from casual interactions and enjoyed them immensely. My time at the University of Alberta has also allowed me to interact with several remarkable individuals including members of my candidacy examining committee: Drs. Edward Bork and Steven Strelkov. Notables also include several graduate students of this department and the Department of Biological Sciences. Thanks to Jeremy Hummel, Ravindran Subramaniam, Adam Blake, Amanda Van Haga, Artem Abdukakharov, Caroline Whitehouse, Jason Dombroskie, Joelle Lemmen, Kelley Dunfield, Lisa Lumley, Marla Schwarzfeld, Rana Sarfraz , Tyler Wist, Acknowledgements Wes Hunting, Dr. Thomas Simonsen, Chris Miluch, Mark McPherson and Philip Batista for their contributions to this experience. Also, thanks to Freddie Brent Young, Michael Cripps and Dr. James ‘Ding’ Johnson for their contributions to another related experience. Funding for this project was provided by the University of Alberta, the Canola Council of Canada and grants to LMD from the Natural Sciences and Engineering Research Council of Canada and the Alberta Agricultural Research Institute and I am grateful for their support of this project. Table of Contents Chapter 1. Introduction 1 Ceutorhynchus obstrictus (Marsham), the cabbage seedpod weevil 2 Life history 2 Ceutorhynchus obstrictus : Taxonomic status 5 Diagnostic characters 8 Origins, distribution and predicted spread of North American 10 populations Economic importance of C. obstrictus 13 Control strategies 17 Chemical control 17 Trap crops 19 Natural enemies 20 Development of resistant germplasm 24 Interactions with host plants 26 Glucosinolates 26 Chemical differences among S. alba x B. napus genotypes 30 Vision in C. obstrictus 31 Visual cues and host selection 33 Olfactory cues 36 Antixenosis resistance