AN ABSTRACT OF THE DISSERTATION OF Daniel M. McGrath for the degree of Doctor of Philosophyin Entomology presented on February 15, 2000. Title: Conservation ofArthropod Natural Enemies in Broccoli with Relay Strip-Cropping Redacted for privacy Abstract approved: Relay strip-cropping combines two vegetation management tactics,under- sowing and strip-management. In this study conductedfrom 1994 though 1997, a cover crop seed-mixture containing oats (Avena sativa L.var. "Monida"), common vetch ( Vicia sativa L.), red clover (Tr4foliumpratense L.), annual ryegrass (Lolium multflorum Lam.), and buckwheat (Fagopyrum esculentumMoench) was broadcast over established broccoli (Brassica oleracea L.) 32days after planting. The broccoli was planted, under-sown, and harvestedin sections alternated with strips of cover crop. Thecover crop relay provided tillage and pesticide refuges for beneficial insects without taking landout of broccoli production. Relay strip- cropping increased the abundance and diversity of groundbeetles (Coleoptera: Carabidae), spiders (Araneae), harvestmen (Opiliones: Phalangiidae),lady beetles (Coleoptera: Coccinellidae), and damsel bugs (Heteroptera: Nabidae)in the cropping system; however, this did not always result inincreased natural enemies in the broccoli. Arthropod species varied significantly in theirpropensity to leave the non-crop vegetation andmove into the broccoli. Movement of the lady beetle Coccinella septempunctata L. from thecover crop strips into the broccoli may have depressed aphid populations in 1996. Thenon-crop vegetation may have served as a sink rather than a source for Nabis species and appeared to reduce their density in the broccoli growing nearby. Therewas no evidence that background vegetation surrounding the broccoli reduced colonization by winged aphids.The density of the cabbage flea beetle Phyllotreta crucferae Goezewas lower in the broccoli relay compared with the clean-tilled broccoli. The number of thirdinstar imported cabbage worm Pieris rapae (L.) and cabbagelooper Trichoplusia ni (Hubner) was reduced on broccoli leaves and harvested buds inthe relay strip-cropping system compared with the clean-tilled system. The numberof diamondback moth Plutella xylostella (L.) pupae was higher in the clean-tilledbroccoli; percent parasitism of the pupae was similar in thetwo cropping systems. Although reduction in broccoli contamination associated with relay strip-croppingwas significant, the residual insect contamination was unacceptable forcommercial broccoli production. Relay strip-cropping may be useful for preventing soilerosion and protecting water quality. Relay strip-croppingmay be a useful component of an integrated pest management program. ©Copyright by Daniel M. McGrath February 15, 2000 All Rights Reserved Conservation of Arthropod Natural Enemies in Broccoli with Relay Strip-Cropping by Daniel M. McGrath A DISSERTATION submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Presented February 15, 2000 Commencement June 2000 Doctor of Philosophy DISSERTATION of Daniel M. McGrath presented on February 15, 2000. APPROVED: Redacted for privacy Majoy'Pthfessor, reprsning Entomology Redacted for privacy of Departme'T{t o'f Entomology Redacted for privacy Dean of Gtaluate School I understand that my DISSERTATION will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my DISSERTATION to any reader upon request. Redacted for privacy 1 ACKNOWLEDGMENTS I would like to thank my major professor, Dr. Marcos Kogan for his guidance and encouragement. I would also like to thankmy graduate committee members Dr. Arnold P. Appleby, Dr. Ralph E. Berry, Dr. Kenneth B. Johnson, and Dr. Jeffrey C. Miller for their suggestions and comments. My wife Darryla, who gave constant support, made this Ph.D. program possible. Special thanks are offered to Elizabeth Harrison and Carl Pils who provided technical support. I would also like to thank James LaBorite, Dr. Andrew Moldenke, and Dr. Jack Latin for assisting with the identification of carabid beetle, spider, and heteropteran species respectively. I very much appreciate the support and encouragement that I received from the OSU Extension administration and my immediate supervisor, John Burt. To our department chair, Dr. Paul Jepson, our clerical support staff Linda Parks, Deanna Watkins, and Mary Murphy, and the many people who have helped me along the way, thank you very much. It has meanta great deal to me. 11 TABLE OF CONTENTS CHAPTER Page 1 HOST PLANT DEFENSES AND VEGETATION 7 MANAGEMENT VEGETATION MANAGEMENT AND COLONIZATION 12 Early colonizers and crop adapted species 13 Background vegetation, stand purity, and immigration 17 Stand purity, patch tenure time, and emigration 20 Stand purity and natural enemies 30 Structural complexity and patch size 32 TILLAGE AND PESTICIDE REFUGES FOR NATURAL 37 ENEMIES RELAY STRIP CROPPING 46 OBJECTIVES 48 2. IMPACT OF RELAY STRIP CROPPING ON GROUND 51 BEETLES (COLEOPTERA: CARABIDAE) IN BROCCOLI ABSTRACT 52 INTRODUCTION 53 MATERIALS AND METHODS 59 Site description 59 Relay strip cropping experiments 1994-1996 60 Pitfall sampling 65 Mark, release, and recapture experiment 1997 66 Statistical methods 67 RESULTS 68 DISCUSSION 93 111 TABLE OF CONTENTS (Continued) CHAPTER Page 3. IMPACT OF RELAY STRIP CROPPING ON SPIDERS 99 (ARAENEA) AND HARVESTMEN (OPILIONES) IN BROCCOLI ABSTRACT 100 INTRODUCTION 100 MATERIALS AND METHODS 109 Vacuum sampling 110 Statistical methods 111 RESULTS 112 DISCUSSION 151 4. IMPACT OF RELAY STRIP CROPPING ON LADY 159 BEETLES (COLEOPTERA: COCCNIELLIDAE) IN BROCCOLI ABSTRACT 160 INTRODUCTION 161 MATERIALS AND METHODS 170 RESULTS 170 DISCUSSION 186 5. IMPACT OF RELAY STRIP CROPPING ON DAMSEL BUGS 192 (HETEROPTERA: NABIDAE) IN BROCCOLI ABSTRACT 193 1NFRODUCTION 193 MATERIALS AND METHODS 199 RESULTS 200 DISCUSSION 206 lv TABLE OF CONTENTS (Continued) CHAPTER Page 6. SUMMARY: THE IMPACT OF RELAY STRIP CROPPING 210 ON INSECT PESTS OF BROCCOLI ABSTRACT 211 INTRODUCTION 212 Brevicoryne brassicae (L.) 215 Phyllotreta crucferae Goeze 222 Pieris rapae (L.) 225 Plutella xylostella (L.) 230 Trichoplusia ni (Hubner) 235 Relay strip cropping 236 MATERIALS AND METHODS 240 Under-sowing timing experiments 1994 and 1996 240 Leaf sampling 242 Statistical methods 242 RESULTS 242 DISCUSSION 288 BIBLIOGRAPHY 295 APPENDICES 340 APPENDIX A: CARABIDAE LITERATURE REVIEW 341 APPENDIX B: SPIDER AND HARVESTMEN LITERATURE 410 REVIEW APPENDIX C: COCCINELLIDAE LITERATURE REVIEW 452 APPENDIX D: NABIDAE LITERATURE REVIEW 505 APPENDIX E: BROCCOLI INSECT LITERATURE REVIEW 528 V LIST OF FIGURES Figure Page 2.1 Relay Strip-cropping Experiment Winter Cover Crop vs Fallow 61 2.2 Three Phases of the Relay Strip-cropping System for Broccoli 63 2.3 Impact of Relay Strip-cropping on Pterostichus melanarius 77 in BroccoliCorvallis, Oregon 1994 2.4 Response of Pterostichus melanarius to Habitat Choices 77 in a Broccoli Relay- Corvallis, Oregon 1994 2.5 Impact of Relay Strip-cropping on Pterostichus melanarius 78 in BroccoliCorvallis, Oregon 1995 2.6 Response of Pterostichus melanarius to Habitat Choices 78 in a Broccoli Relay Corvallis, Oregon 1995 2.7 Impact of Relay Strip-cropping on Pterostichus melanarius 79 in BroccoliCorvallis, Oregon 1996 2.8 Response of Pterostichus melanarius to Habitat Choices 79 in a Broccoli Relay- Corvallis, Oregon 1996 2.9 Impact of Relay Strip-cropping on Anisodactylus binotatus 82 in Broccoli - Corvallis, Oregon 1994 2.10 Response of Anisodactylus binotatus to Habitat Choices 82 in a Broccoli Relay- Corvallis, Oregon 1994 2.11 Impact of Relay Strip-cropping on Anisodactylus binotatus 83 in Broccoli - Corvallis, Oregon 1995 2.12 Response of Anisodactylus binotatus to Habitat Choices 83 in a Broccoli Relay- Corvallis, Oregon 1995 2.13 Impact of Relay Strip-cropping on Anisodactylus binotatus 84 in Broccoli- Corvallis, Oregon 1996 vi LIST OF FIGURES (Continued) Figure Page 2.14 Response of Anisodactylus binotatus to Habitat Choices 84 in a Broccoli Relay - Corvallis, Oregon 1996 2.15 Impact of Relay Strip-cropping on Bradycellus con gener in BroccoliCorvallis, Oregon 1994 2.16 Response of Bradycellus congener to Habitat Choices in a Broccoli Relay - Corvallis, Oregon 1994 2.17 Impact of Relay Strip-cropping on Bradycellus congener in BroccoliCorvallis, Oregon 1996 2.18 Response of Bradycellus congener to Habitat Choices in a Broccoli Relay - Corvallis, Oregon 1996 2.19 Impact of Relay Strip-cropping on Amara Species 91 in Broccoli - Corvallis, Oregon 1994 2.20 Response of Amara Species to Habitat Choices ;,J] in a Broccoli Relay- Corvallis, Oregon 1994 2.21 Impact of Relay Strip-cropping on Amara Species in Broccoli - Corvallis, Oregon 1996 2.22 Response of Amara Species to Habitat Choices in a Broccoli Relay- Corvallis, Oregon 1996 3.1 Spider and Harvestmen Families in a Broccoli Cover Crop Relay 117 Corvallis, Oregon 1994-1996 3.2 Spider and Harvestmen Species in a Broccoli Cover Crop Relay 118 Corvallis, Oregon 1994-1996 3.3 Spider and Harvestmen Families Ftv in a Broccoli Relay Strip-cropping System Corvallis, Oregon 1994-1996 vi' LIST OF FIGURES (Continued) Figure Page 3.4 Spider and Harvestmen in a Broccoli 120 Relay Strip-cropping System Corvallis, Oregon 1994-1996 3.5 Impact of Relay Strip-cropping on Erigone dentosa in Broccoli 125 (Pitfall Trapping) Corvallis, Oregon 1994 3.6 Response of Erigone dentosa to Habitat Choices in a Broccoli 125 Cover Crop Relay (Pitfall