Novel Control Strategy for Bagrada Hilaris (Burmeister)
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NOVEL CONTROL STRATEGY FOR BAGRADA HILARIS (BURMEISTER) A Thesis Presented to the Faculty of California State Polytechnic University, Pomona In Partial Fulfillment Of the Requirements for the Degree Master of Science In Plant Science By Tasien L. Somé 2020 SIGNATURE PAGE THESIS: NOVEL CONTROL STRATEGY FOR BAGRADA HILARIS (BURMEISTER) AUTHOR: Tasien L. Somé DATE SUBMITTED: Fall 2020 Department of Plant Science Dr. Aaron Fox _______________________________________ Thesis Committee Chair Plant Science Dr. Anna Soper _______________________________________ Assistant Professor Plant Science Dr. Dawn Calibeo ________________________________________ Pre-Commercial Development Gowan Company, Yuma, AZ ii ACKNOWLEDGEMENTS I would like to present my gratitude to all my advisors, Dr. Aaron Fox, Dr. Anna Soper, and Dr. Dawn Calibeo for their continuous availabilities, knowledge and support for my Master thesis study and research. I am honored to receive the guidance, and benefited from the diverse education background of all these great professors. In addition, I would like express my thanks to Dr. Robert Green for guiding me through all my study trials and sharing all his statistics and data analytical knowledge that contributed to the success of the research. I would also like to thank Dr. Valerie Mellano, the chair of the Plant Science department, Dr. Shelton Murinda, the chair of Animal & Veterinary Sciences department and Dr. Oliver Li, Nutrition & Food Science department for their supports. For, I want to express my gratitude to Dr. David Morgan and all his staffs from CDFA for making a section of the greenhouse and some equipment available for this study. I would like to especially thank Dr. Lisa Kessler, the interim dean and Dr. Peter Kilduff the vice dean of The Don B. Huntley College of Agriculture for their supports. Lastly, I want to thank Dr. Thomas Perring form UCR and all his staffs for rearing the insects throughout the entire research period. iii ABSTRACT California and Arizona farmers are the major growers of cole crops in the United States, and broccoli is considered to be economically one of their most important cash crops. Broccoli is grown organically and conventionally in California and Arizona. In 2008, a new invasive insect, Bagrada hilaris, was discovered in Los Angeles. Bagrada. hilaris quickly became a major pest for California and Arizona cole crop growers. Extensive damage was reported and B. hilaris required innovative pest management strategies. Conventional growers effectively used synthetic pesticides to keep B. hilaris damage levels low. However, there were fewer options for organic growers to control the pest. Naturally, plants use secondary metabolites as a defense mechanism to protect themselves from herbivores. Promoting broccoli secondary metabolites as a defense mechanism could benefit organic broccoli growers and decrease pesticides usage for all growers. There is evidence from the literature that organically managed crops produce higher concentrations of secondary metabolites, such as glucosinolate (GLs). We hypothesized that organically grown brocccoli would be less attractive to B. hilaris due to higher concentrations of secondary metabolites. A greenhouse Choice Study was designed to investigate B. hilaris feeding activities on three treatments of broccoli seedlings (Brassica oleracea var. italica). The three treatments were organically fertilized seedlings (Organic), seedlings fertilized with synthetic fertilizer (Synthetic), and a control treatment where seedlings only received water (Control). The experimental design used was a randomized complete block design with multiple No-choice and Choice trials. In the No-Choice trials, adult B. hilaris were offered only one treatment, either Organic, Synthetic, or Control. In the Choice trials, adults B. hilaris were offered all three iv treatments. Observations of B. hilaris behavior and broccoli conditions were recorded at 30 minutes, and 1, 2, 4, 8, 12, 24 and 48 hours from the time of release of the insects. During each recording time, the following observations were made: the number of B. hilaris on the seedlings, the number of leaves injured per cage, and the number of plants showing injury. At the end of each trial, at 48 hours, the percent leaf area damage and the percentage of dead seedlings were recorded. Photosynthetic activity and temperature inside the cages in the greenhouse were measured and analyzed. Glucosinolate concentrations in the seedlings were tested from one Choice trial. Overall, B. hilaris did not consistently prefer one treatment over the other in our study. Only in one of the Choice trials were the Synthetic seedlings clearly preferred by B. hilaris feeding. While our results may not provide clear guidance for broccoli growers, our results show there is opportunity for further investigation. v TABLE OF CONTENTS Signature Page………………………………………………………………...ii Acknowledgements………………………………………………………......iii Abstract………………………………………………………………………iv 1.Introduction…………………………………………………………………1 1.1 Bagrada hilaris origins and life cycle……...………………………...……3 1.2 Bagrada hilaris feeding activities..……………………………...………...4 1.3 Economic losses……………………………….………………………….4 1.4 Transplant versus direct seeding….……………………………..………..6 1.5 Conventional field management methods of (brassica oleracea var. italic) ………………………………………………………………………………...7 1.6 Organic field management protocol for USDA.……………..…………...7 1.7 Organic field management methods of (brassica oleracea var. italic)……8 1.8 Benefits of organically grown broccoli………………………………...…9 1.9 Brassicaceae defense compounds…………………………………………9 2. Objective and Hypothesis…………………………………………………14 3. Materials and Methods……………………………………………………17 3.1 Glucosinolate analysis…………………………………………………...20 3.2 Temperature and photosynthetically activities radiation analysis (PAR).. ………………………………………………………………………….……21 4. Statistics Analysis…………………………………………………………22 5. Results…………………………………………………………………….24 vi 5.1 Choice study results for season 1 and 2.………………………………..24 5.2 No-Choice study results for season 1 and 2……………….…………....26 5.3 Laboratory analysis of glucosinolate (GLs) concentration results………28 5.4 Temperature and photosynthetically activities radiation results………...28 6. Discussion…………………………………………………………............30 Conclusion…………………………………………………………………...36 References……...............................................................................................38 Appendix A (Tables)………………………………………………...............48 Appendix B (Figures)………………………………………………………..60 vii 1. Introduction Insects from Pentatomidae family (order Hemiptera) are commonly known as stink bugs. Many are phytophagous, but some are predators such as the ones belonging to the subfamily (Asopinae) (Azim, 2011; Raupp et al., 2019). Pentatomidae feeding behaviors are often broad and unpredictable (Torres-Acosta and Sánchez-Peña, 2016) but some are very specific. Bagrada hilaris (Burmeister) is an important pest on agricultural crops (Torres-Acosta and Sánchez-Peña, 2016). Bagrada hilaris origins are thought to be from Africa, Asia (Guarino et al., 2018), and some parts of Europe (Huang et al., 2013; Reed et al., 2015). Bagrada hilaris was discovered in Southern California around the year 2008 as a pest in the Los Angeles area. Since then, it has migrated to different regions of the state (Matsunaga, 2014). In the past decade, B. hilaris has become an invasive pest in California and Arizona, especially on Brassicaceae crops (Palumbo and Carrière, 2015). Bagrada hilaris is not host specific because it feeds on a wide range of other crops including different varieties of wild plants. It was also found to be feeding on grass family and taproot plants (Reed et al., 2013). In general, young seedlings are the most vulnerable to phytophagous insects like B. hilaris, because the insect normally damages the epical meristem and stunts the plant growth (Hodges, and LeVeen, 2018; Azim, 2011). Bagrada hilaris as a stink bug, possesses mouthparts that pierce and suck plants during feeding sessions (Kuhar et al., 2015; Azim, 2011). The insect pest feeds on every part of the Brassicaceae plant such as leaves, stems, seeds and flowers by piercing and sucking (Huang et al., 2013). Bagrada. hilaris feeding damage produces stunting, scorched leaves, wilt, and lesions on plants. As result, the plants either die (Plantwise, 2012), or, if the plants survive, crops produced are often unmarketable (Palumbo and 1 Carriere, 2015). Furthermore, one study has reported that insect damage in fields is concomitant with the pests’ distribution in those fields locations (Lillian et al., 2018). Therefore, damage caused by insect pests in small and large farms worldwide have been a major concern. Numerous research projects have details the life-cycle of B. hilaris. The population of B. hilaris seems to peak in the desert region during Fall, Spring and peak in Coastal regions during the Summer. These are the times when temperature is around twenty-nine degrees Celsius and there is an abundance of food supply (Grettenberger et al., 2016; (Hodges and LeVeen, 2018; Palumbo 2015, Huang et al., 2013). This insect pest prefers undisturbed fields where they can congregate in groups of hundreds (Hodges and LeVeen, 2018). Bagrada hilaris’ population tends to be dense on host plants (Palumbo and Carriere, 2015), because of the overlapping generation. Optimal condition for B. hilaris reproduction are at 29.40C daytime temperature with 82.0% moisture level, and 8.40C nighttime temperature with 24.06%