Conservation Biological Control of Western Bean Cutworm: Molecular
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Dissertations and Student Research in Entomology Entomology, Department of 8-2017 Conservation Biological Control of Western Bean Cutworm: Molecular gut content analysis of arthropod predators, feeding trials for key predators and agricultural surveys for integrated pest management Westen Ray Archibald University of Nebraska-Lincoln Follow this and additional works at: http://digitalcommons.unl.edu/entomologydiss Part of the Entomology Commons Archibald, Westen Ray, "Conservation Biological Control of Western Bean Cutworm: Molecular gut content analysis of arthropod predators, feeding trials for key predators and agricultural surveys for integrated pest management" (2017). Dissertations and Student Research in Entomology. 49. http://digitalcommons.unl.edu/entomologydiss/49 This Article is brought to you for free and open access by the Entomology, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Dissertations and Student Research in Entomology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. i Conservation Biological Control of Western Bean Cutworm: Molecular gut content analysis of arthropod predators, feeding trials for key predators and agricultural surveys for integrated pest management by Westen Ray Archibald A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science Major: Entomology Under the Supervision of Professors Julie Peterson and Robert Wright Lincoln, Nebraska August 2017 ii Conservation Biological Control of Western Bean Cutworm: Molecular gut content analysis of arthropod predators, feeding trials for key predators and agricultural surveys for integrated pest management Westen Ray Archibald, M.S. University of Nebraska, 2017 Advisors: Julie A. Peterson and Robert J. Wright Western bean cutworm (WBC), Striacosta albicosta is a major pest of corn in western Nebraska. In 1999, its range expanded into much of North America causing damage from Nebraska to Canada and Mexico. WBC periodically causes kernel damage as severe as 15 bu/ac for one larva/plant. Control for WBC relies on Bt corn hybrids with Vip3A and Cry1F traits and insecticides. There has been a 5.2-fold decrease in efficacy of Cry1F for WBC. Concerns over management tactics may be creating space for conservation biological control to become part of a WBC integrated pest management (IPM) program. Objective 1, used an online survey to determine Nebraska stakeholder concerns, understanding, and practices for WBC IPM. Respondents self-reported significantly higher yield loss due to WBC in 2016 than in 2015 and 2014. Growers demonstrated low knowledge of WBC identification and management. There were frequent reports (58.45%) of Cry1F Bt corn providing decreased control against WBC. In objective 2, predator surveys for natural enemies of WBC indicated that four generalist predators were ubiquitous in Nebraska corn fields. Some species had population dynamics that were associated with the WBC population dynamics in corn. Lab-based feeding trials indicated that Coleomegilla maculata (De Geer) was a superior predator for WBC eggs and larvae. However, molecular gut content analysis of surveyed predators found in-field predation by multiple generalist predators but not C. maculata. By determining the needs iii of growers and the role of predators for WBC, conservation biological control may be incorporated into a WBC IPM program. iv Acknowledgements I would like to thank my Co-advisors Julie A. Peterson and Robert J. Wright and committee member Jeff Bradshaw for their support, guidance, corrections, and wisdom. Also, thank you for sharing your resources funding this project. Thank you to the USDA-Critical Agricultural Research & Extension Grant #2015-67028- 23519 and USDA-HATCH Multistate Project #NEB-42-113 for funding this project. Thank you to the Entomology Department, especially the many wonderful members of the Agroecosystems Entomology Lab. Kayla Mollet and Grace Hirzel for your excellent help as technicians. Alex Lehmann for helping with collecting predators. Débora Montezano and Camila Oliveira Hofman for your guidance and help in this process. Thanks to Dr. Tony Adesemoye and his lab for sharing their molecular equipment and facilities with me. Thank you to Dr. Brewer, Chief Charles Ragland, the Bruner Club, and the U.S. Navy for teaching me that the military needs entomologists and helping bring so many dreams together in one place. Thank you to the USDA National Agricultural Statistical Service for helping me at the beginning stages of survey design. Thank you to Jason Adams and YouTube for helping me with my statistics. A special thanks to all the friends and family who have helped me through this process of discovery and growth. v Table of Contents Acknowledgements ............................................................................................................ iv Table of Contents ................................................................................................................ v Table of Figure Legends .................................................................................................. vii List of Tables ................................................................................................................... viii Chapter 1 : Review of Literature ....................................................................................... 1 Western bean cutworm ................................................................................................. 1 Biology and ecology ............................................................................................................................... 1 Range and expansion .............................................................................................................................. 4 Surveys for integrated pest management .................................................................... 7 Current western bean cutworm management practices ............................................ 8 Injury ...................................................................................................................................................... 8 Trapping adults ....................................................................................................................................... 9 Scouting ................................................................................................................................................ 10 Foliar insecticides ................................................................................................................................. 11 Cultural methods................................................................................................................................... 12 Transgenic corn .................................................................................................................................... 12 Biological control of western bean cutworm............................................................. 13 Biological control of other lepidopteran pests .......................................................... 15 Spodoptera frugiperda .......................................................................................................................... 15 Helicoverpa zea .................................................................................................................................... 16 Ostrinia nubilalis................................................................................................................................... 17 Coleomegilla maculata ................................................................................................ 17 Biology and ecology ............................................................................................................................. 17 Coleomegilla maculata in biological control ........................................................................................ 19 Chapter 2 : Using an online survey to measure Nebraska stakeholders’ understanding and implementation of western bean cutworm ............................................................... 22 Materials and Methods ............................................................................................... 23 Survey design ....................................................................................................................................... 23 Results .......................................................................................................................... 24 Distribution of responses ...................................................................................................................... 24 WBC damage in 2014- 2016 ................................................................................................................ 27 Scouting practices ................................................................................................................................. 28 Degree day models ............................................................................................................................... 31 Confidence with managing western bean cutworm .............................................................................. 31 Bt corn performance