THE ROLE OF NATURAL ENEMIES IN PEST MANAGEMENT OF CODLING MOTH (CYDIA POMONELLA [L.]) IN ORGANIC APPLE ORCHARDS IN MICHIGAN

By

Nathaniel James Walton

A DISSERTATION

Submitted to Michigan State University in partial fulfillment of the requirements for the degree of

Entomology - Doctor of Philosophy Ecology, Evolutionary Biology and Behavior - Dual Major

2013

ABSTRACT

THE ROLE OF NATURAL ENEMIES IN PEST MANAGEMENT OF CODLING MOTH (CYDIA POMONELLA [L.]) IN ORGANIC APPLE ORCHARDS IN MICHIGAN

By

Nathaniel James Walton

The codling moth (Cydia Pomonella [L.]) is the number one worldwide pest of apples, pears and other pome fruits. Conservation of natural enemies is one way to reduce the costs of managing this pest by reducing the need for insecticide sprays.

Successful conservation of the codling moth’s natural enemies in Michigan requires 1) identifying them and 2) determining major factors that affect their abundance and effectiveness in the apple agroecosystem. The first chapter of my dissertation presents a literature review of the major natural enemies of codling moth by life stage. The second chapter presents a field study using real time video observation of sentinel prey to identify codling moth’s key natural enemies in Michigan apple orchards. The third chapter provides experimental data and analysis aimed at identifying major factors that may impact the efficacy of natural enemies in Michigan orchards. In chapter 4 I present the results of two laboratory investigations exploring behavioral factors affecting codling moth infection by entomopathogenic nematodes. I identified, ants, lacewings, spiders, and predatory beetles as major natural enemies of codling moth in my experimental apple orchards. Relative abundances of these organisms were very site-specific.

Organically certified orchards had higher natural enemy abundance and attack rate of sentinel fifth instar codling moth compared to non-organic orchards. This was not found for codling moth egg natural enemy abundance or activity. Further investigations revealed that orchard sanitation and orchard floor vegetation management affect natural enemy abundance and effectiveness against fifth instar codling moth larvae and codling moth pupae on the orchard floor. The implications of these findings for organic pest management and for future avenues of research are also discussed in the concluding chapter. ACKNOWLEDGEMENTS

The work contained in this dissertation could not have been completed without the help of innumerable researchers worldwide who provided the groundwork upon which this research was based. In addition to those individuals, I would also like to thank specifically a number of people who were directly involved in helping me to carry out the research studies contained herein. Firstly, my graduate advisor Matthew

Grieshop without whose support none of this would have been possible. I'd also like to thank Jim Koan and Steve Tennes for providing their farms as research sites. Michelle

Brosius assisted in carrying out the majority of the field and laboratory experiments contained in this dissertation and her insight was always invaluable. Other members of the Organic Pest Management team that provided assistance during the course of this research include: Emily Pochubay, Ben Phillips, Krista Buehrer, Joe Riddle, Vianney

Willot, Phil Kavouriaris, Shane Celeste, Kristy Morell, Kristin Deroshia, Michael Kelleher,

Matt Quenado, and many others. I would also like to thank the members of my

Graduate Advisory Committee: Doug Landis, Larry Gut, and Chris Klausmeier. This research was funded primarily by the USDA, Ceres Trust, and Project GREEEN.

Finally, I would like to thank Emily Pochubay, Dave Epstein, Anne Nielsen, Julianna

Wilson, Rufus Isaacs, and Steppin' in it, for providing guidance, advice, moral support, and dancin' music througho