Development of a Degree Day Model and Economic Thresholds for Cerotoma trifurcata (Coleoptera: Chrysomelidae) in Ontario by Cara M. McCreary A Thesis presented to The University of Guelph In partial fulfilment of requirements for the degree of Master of Science in Environmental Biology Guelph, Ontario, Canada © Cara M. McCreary, August, 2013 ABSTRACT DEVELOPMENT OF A DEGREE DAY MODEL AND ECONOMIC THRESHOLDS FOR CEROTOMA TRIFURCATA (COLEOPTERA: CHRYSOMELIDAE) IN ONTARIO Cara Michele McCreary Advisors: University of Guelph, 2013 Rebecca H. Hallett Art W. Schaafsma Bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), is an economic pest of soybean in Ontario. Field cage studies were conducted in 2010-2011 to determine voltinism in southern Ontario and the effect of C. trifurcata feeding during soybean reproductive stages on soybean yield and quality. Thermal requirements for C. trifurcata development were determined in a laboratory study. Results of field and laboratory studies support the occurrence of one generation of C. trifurcata in southern Ontario. Pod-feeding increased with both number of beetles and soybean reproductive stage. An increase in defoliation and a reduction in seed quality were observed with increasing number of beetles. Monitoring programs for late-season pod-feeding should begin when degree days approach 500 (base 9.31°C). Economic thresholds for C. trifurcata during soybean reproductive stages range from 0.27 to 2.00 beetles per plant or 8 to 60 beetles per m of row. Acknowledgements It is with immense gratitude that I acknowledge my co-advisors Drs. Rebecca Hallett and Art Schaafsma for their support and guidance throughout my thesis research. Rebecca was instrumental in my career development by providing me with a background in graduate research as I worked in her lab before beginning my own studies. Rebecca’s encouragement and confidence in me throughout my research helped me develop invaluable skills allowing me to continue a career in research. Art’s irreplaceable knowledge and enthusiasm was an inspiration for my own work. Art was willing to take time to advise me on unforeseen obstacles as they arose and help me focus on my research goals. I am truly indebted and thankful to Jocelyn Smith for her dedication and contributions. Jocelyn’s expertise and preliminary work on C. trifurcata was a valuable contribution to the success of my own research. Special thanks also goes to Christie Bahlai for her motherly guidance and her late-night statistical counseling. I would like to thank Tracey Baute from the Ontario Ministry of Agriculture and Food, for helping to locate C. trifurcata in southern Ontario and offering field assistance. I owe sincere thankfulness to my third advisory committee member, Dr. Greg Boland, for his timely advice and support. This thesis would not have been possible without the technical and field assistance of Todd Phibbs, Jen Bruggeman, Erin LeClair, Heather Cumming, David Makynen, Braden Evans, Mike Schmidt, Kaitlyn Madge, Scott Lewis, Adam Brunke and Dave Cheung. Additional thanks to the technical staff at Ridgetown Campus for their treasured advice and moral support from Bryan Stirling, Dennis Fisher, Mike Zink and Scott Jay. I would also like to thank the co- operators that allowed access and use of their soybean fields for beetle collection and cage iii studies. Finally, I am eternally grateful to my friends, family and present colleagues for their ongoing support and encouragement. Great thanks to the late Peggy Buck, my beloved honorary Great Aunt. Peggy was the greatest motivation for my pursuit of graduate studies and was looking forward to attending my defense, but left this world too soon. I owe sincere and earnest thankfulness to my boyfriend Jeremy Pfaff, my parents and step-parents, Jim and Karen McCreary, Jackie McCreary and Barry Ashby, my in-laws Harold and Sharon Pfaff, as well as my brother and sister in-law, James and Maggy McCreary. Finally, I would like to thank my current supervisor in my position as a Research Technician in the Edible Bean Program at Ridgetown Campus, Chris Gillard, and the Edible Bean Lab, Lindsey Goudis and Ally Friesen. Funding for this thesis was provided by the Ontario Ministry of Agriculture and Food – University of Guelph Sustainable Production (Plants) Program, and by the Grain Farmers of Ontario through the Farm Innovation Program. iv Table of Contents Acknowledgements ................................................................................................................... iii Table of Contents ....................................................................................................................... v List of Tables .......................................................................................................................... vii List of Figures ............................................................................................................................ix Table of Acronyms................................................................................................................... xii CHAPTER ONE: Literature Review 1.1 Introduction ........................................................................................................................... 1 1.2 Classification and Distribution of Bean Leaf Beatle, Cerotoma trifurcata .............................. 2 1.3 Identification ......................................................................................................................... 3 1.4 Life History and Biology ....................................................................................................... 4 1.4.1 Phenology ................................................................................................................. 4 1.4.2 Feeding Behaviour .................................................................................................... 7 1.4.3 Overwintering Behaviour and Diapause .................................................................... 9 1.4.4 Abundance, Dispersion and Migration..................................................................... 10 1.5 Degree Day Models ............................................................................................................. 11 1.6 Soybean Pathogens Associated with Cerotoma trifurcata .................................................... 13 1.6.1 Bean Pod Mottle Virus Acquisition, Transmission and Symptomology ................... 13 1.6.2 Bean Pod Mottle Virus and Soybean Mosaic Virus ................................................. 14 1.6.3 Fungal Pathogens .................................................................................................... 15 1.7 Economic Importance .......................................................................................................... 16 1.7.1 Soybean Production ................................................................................................ 16 1.7.2 Economic Impact of Feeding Damage ..................................................................... 17 1.7.3 Economic Impact of Pathogens ............................................................................... 18 1.7.4 Economic Injury Level ............................................................................................ 19 1.8 Management ........................................................................................................................ 21 1.8.1 Monitoring .............................................................................................................. 21 1.8.2 Cultural Management .............................................................................................. 22 1.8.3 Chemical Management ............................................................................................ 23 1.8.4 Host Plant Resistance .............................................................................................. 24 1.8.5 Biological Control ................................................................................................... 24 1.8.6 Pathogen Vector Management ................................................................................. 25 1.9 Research Objectives ............................................................................................................ 26 CHAPTER TWO: Temperature-Dependent Development and Degree Day Requirements of Bean Leaf Beetle, Cerotoma trifurcata, under Constant Temperature Regimes. 2.1 Abstract ............................................................................................................................... 27 2.2 Introduction ......................................................................................................................... 28 2.3 Materials and Methods ........................................................................................................ 29 2.3.1 Rearing Methods ..................................................................................................... 32 2.3.2 Statistical Analysis .................................................................................................. 33 2.3.3 Degree Day Model .................................................................................................. 34 2.4 Results ................................................................................................................................ 35 v 2.4.1 Survivorship ...........................................................................................................