TOXICITY, EXPOSURE, AND RISK OF INSECTICIDES USED FOR MOSQUITO MANAGEMENT ON THE ALFALFA LEAFCUTTING BEE, MEGACHILE ROTUNDATA by Alyssa Margaret Piccolomini A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Entomology MONTANA STATE UNIVERSITY Bozeman, Montana July 2017 ©COPYRIGHT by Alyssa Margaret Piccolomini 2017 All Rights Reserved ii DEDICATION I would like to dedicate this thesis to my sister, Jenny, whose wedding I nearly missed in order to see this through completion. Thank you for your continued support and for being one of my biggest cheerleaders. I go down to the shore in the morning and depending on the hour the waves are rolling in or moving out, and I say, oh, I am miserable, what shall what should I do? And the sea says in its lovely voice: Excuse me, I have work to do. -Mary Oliver, I Go Down to the Shore iii ACKNOWLEDGEMENTS First and foremost, I would like to thank my major advisor, Dr. Bob Peterson for the continuous support and guidance. You have given me the tools to become successful in the science field and for that, I am eternally grateful for my time spent here at MSU in your lab. Additionally, I thank my committee members, Dr. Michelle Flenniken and Dr. Kevin O’Neill for their support and guidance as well as Dr. Casey Delphia and Ruth O’Neill for their continued support throughout this project. I am grateful to the Mosquito Research Foundation and the Montana Agricultural Experiment Station for funding my graduate studies. Special thanks to the Department of Land Resources and Environmental Sciences for providing a positive learning environment. I would also like to thank past and present members of the CoBRA Lab, especially Dr. Collin Preftakes, Dr. Chris Brown, and Claire Donahoo. I can’t thank you enough for the words of encouragement, after work beers, and laughable moments that helped keep me sane throughout this process. I deeply appreciate everything you have helped me with and feel very thankful I was able to work alongside each of you. I would also like to thank my family and friends for all of their support and understanding through this experience; especially Tess, John, and my dog Reed, who were always up for an outdoor adventure when I needed it most, as well as my parents, who always offered words of encouragement. Finally, I would like to thank Jan Hunter, the first person to give me the strength and confidence to pursue this degree. You have taught me so much, but the most important thing was to work hard and love what you do. iv TABLE OF CONTENTS 1. PROJECT BACKGROUND AND OBJECTIVES .........................................................1 Introduction ......................................................................................................................1 Pyrethroid Insecticides .....................................................................................................2 Exposure of Non-Target Insects to ULV Insecticides .....................................................4 Shift from One Surrogate Species to Another .................................................................6 Why leafcutting bees? ..............................................................................................7 The Life Cycle of Megachile rotundata ..........................................................................9 Objectives and Rationale ...............................................................................................11 2. ACUTE TOXICITY OF PERMETHRIN, DELTAMETHRIN, AND ETOFENPROX TO THE ALFALFA LEAFCUTTING BEE, MEGACHILE ROTUNDATA (HYMENOPTERA: MEGACHILIDAE) ......................12 Contribution of Authors and Co-Authors ......................................................................12 Manuscript Information Page ........................................................................................13 Abstract ..........................................................................................................................14 Introduction ....................................................................................................................15 Materials and Methods ...................................................................................................17 Insects ....................................................................................................................17 Chemicals ...............................................................................................................17 LD50 Bioassay ........................................................................................................18 Respiration .............................................................................................................19 Statistical Analysis .................................................................................................20 Results and Discussion ..................................................................................................21 Acknowledgements ........................................................................................................26 3. LEAF RESIDUE TOXICITY AND RISK OF MOSQUITO INSECTICIDES TO THE BEES, MEGACHILE ROTUNDATA AND APIS MELLIFERA ...............................................................................................32 Contribution of Authors and Co-Authors ......................................................................32 Manuscript Information Page ........................................................................................33 Abstract ..........................................................................................................................34 Introduction ....................................................................................................................35 Materials and Methods ...................................................................................................37 Insects ....................................................................................................................37 Megachile rotundata ..................................................................................37 Apis mellifera .............................................................................................37 v TABLE OF CONTENTS CONTINUED Ultra-low-volume Applicator and Formulations ...................................................38 Experimental Design ..............................................................................................39 Statistical Analysis .................................................................................................41 Results and Discussion ..................................................................................................41 Acknowledgements ........................................................................................................45 4. THE EFFECTS OF AN ULTRA-LOW-VOLUME APPLICATION OF ETOFENPROX FOR MOSQUITO MANAGEMENT ON MEGACHILE ROTUNDATA (HYMENOPTERA: MEGACHILIDAE) LARVAE AND ADULTS IN AN AGRICULTURAL SETTING ...............................51 Contribution of Authors and Co-Authors ......................................................................51 Manuscript Information Page ........................................................................................52 Abstract ..........................................................................................................................53 Introduction ....................................................................................................................54 Materials and Methods ...................................................................................................57 Insects ....................................................................................................................57 Experimental Design ..............................................................................................58 Statistical Analysis .................................................................................................63 Results and Discussion ..................................................................................................63 Acknowledgements ........................................................................................................67 5. CONCLUSION ..............................................................................................................74 REFERENCES CITED ......................................................................................................78 vi LIST OF TABLES Table Page 1. Estimated LD50 and LD90 values for Megachile rotundata ...............................27 2. Droplet density and abundance for each insecticide formulation ......................50 3. Mean droplet density (± SE) of Zenivex® E20 (etofenprox) and abundance near each insecticide-treated nest shelter. .................................70 4. Cumulative number of completed nest tubes by female Megachile rotundata in 2016 .............................................................................73 vii LIST OF FIGURES Figure Page 1. Log changes in respiration as a function of time after dosing at the LD50 value for permethrin (blue) compared to the control, acetone (orange) ......................................................................28 2. Log changes in respiration as a function of time after dosing at the LD50 value for etofenprox (red) compared to the control, acetone (orange) .......................................................................29