Enhanced conservation biological control of light brown apple moth in vineyards Hieu Trung Bui A thesis submitted for the Degree of Doctor of Philosophy in the School of Agriculture, Food and Wine Faculty of Sciences University of Adelaide, Australia May 2018 TABLES OF CONTENS ABSTRACT .......................................................................................................... i DECLARATION .................................................................................................. iii ACKNOWLEDGEMENT ..................................................................................... iv CHAPTER ONE ................................................................................................. 1 General introduction and literature review .......................................................... 1 CHAPTER TWO ........................................................................................ ….33 Behavioural responses of Dolichogenidea tasmanica to alternative hosts are aligned with a conservation biological strategy against light brown apple moth .................... 33 CHAPTER THREE ........................................................................................... 68 Host selections of Dolichogenidea tasmanica and the implications for the conservation biological control of light brown apple moth, Epiphyas postvittana ........................................................................................................ 68 CHAPTER FOUR ........................................................................................... 100 Towards conservation biological control of Epiphyas postvittana (Lepidoptera: Tortricidae) in vineyards: potential value of native plants ............................... 100 CHAPTER FIVE ............................................................................................. 137 General discussion and synthesis .................................................................. 137 ABSTRACT The light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), is the most damaging insect pest of wine grapes in Australia. Biological control contributes to the management of LBAM. This project aims to enhance the conservation biological control of LBAM by examining how the provision of alternative hosts and native flowering plants can sustain parasitoids like Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae). Native plants and alternative host insects that could support conservation biological control of LBAM in South Australian vineyards are evaluated. The contribution that D. tasmanica makes to biological control of LBAM would be more reliable if this wasp parasitises common alternative hosts, maintains populations on them when the grapevines are dormant, and then moves to attack LBAM when it reinvades vineyards. This study examined the foraging behaviour of D. tasmanica on LBAM and two tortricid species that are associated with vineyards, Acropolitis rudisana (Walker) and Merophyas divulsana (Walker). The reciprocal responses of these insect hosts were also studied to determine their susceptibility to wasp attack. During behavioural assays, all hosts were accepted by D. tasmanica with high parasitism rates. The parasitoid responded differently to different host species. These experiments indicate that populations of D. tasmanica should be conserved, and LBAM more reliably suppressed, if the alternative hosts, M. divulsana and A. rudisana, are present. Host choice between E. postvittana and M. dilvusana by D. tasmanica was also studied in a wind tunnel, where the wasp could express its natural searching behaviour. Choices tests were conducted to examine how natal hosts, host i stages and the wasp’s experiences could affect the landing selections of D. tasmanica. Developmental outcomes of parasitoids on different host species were also examined. D. tasmanica exhibited no clear preference for either host. Host species did not affect the body size of the wasp, but did influence its developmental time, probably as a result of differences in the host’s body sizes. The sex ratio of the wasp did not vary between these host species. These results suggest that M. divulsana is a promising alternative host species to support parasitoid populations in vineyards. A field study was conducted to evaluate the potential impacts of candidate plants on biological control of leafrollers, especially LBAM. Five species were planted beside vineyards to provide shelter, nectar and alternative hosts for beneficial insects. The plants were Bursaria spinosa, Leptospermum lanigerum, Hakea mitchellii, Melaleuca lanceolata and Myoporum petiolatum. Similar leafroller abundances and parasitism rates were found between vineyard rows adjacent to the native plants compared to rows furthest from them. The absence of a difference was possibly due to the proximity of the experimental treatment areas and the movement of parasitoids. The results, including increasing parasitoid diversity over time, imply potential benefits of the plants for better leafroller management. The results from my studies suggest that selected supplementary resources can benefit parasitoids and thereby stabilise or enhance biological control of LBAM in vineyards. This research provides a foundation to develop strategies to better suppress LBAM by facilitating more stable biological control. ii DECLARATION I certify that this work contains no material which has been accepted for the award of any other degree or diploma in my name, in any university or other tertiary institution and, to the best of my knowledge and belief, contains no material previously published or written by another person, except where due reference has been made in the text. In addition, I certify that no part of this work will, in the future, be used in a submission in my name, for any other degree or diploma in any university or other tertiary institution without the prior approval of the University of Adelaide and where applicable, any partner institution responsible for the joint-award of this degree. I give permission for the digital version of my thesis to be made available on the web, via the University’s digital research repository, the Library Search and also through web search engines, unless permission has been granted by the University to restrict access for a period of time. Signed Date 8 June 2018 e iii ACKNOWLEDGEMENT First and foremost, my heartfelt gratitude goes to my principle supervisor, Professor Michael A. Keller, for accepting me as his student to pursue my professional development in the field of entomology. His inspiration, mentorship and invaluable advice have significantly improved my confidence and broaden my academic and career visions. I am also grateful to my co-supervisors, Dr Michael Nash and Dr Maryam Yazdani. Thank you all very much for your encouragement, patience, continued support and insightful feedback throughout the entire PhD candidature. I would like to thank the Vietnamese Government and the University of Adelaide for provide me a joint PhD scholarship. Thanks also give to the Australian Grape and Wine Authority for the financial support for my field work through a supplementary scholarship. I would also like to thank my home employer, the Vietnam National University of Forestry, for the continued support me during my PhD process. I am grateful to the entire staff of the School of Agriculture, Food and Wine, Adelaide Graduate Centre, International Student Centre and The South Australian Research and Development Institute (SARDI) for their assistance and support. Also, thanks to Professor Eileen Scott for her encouragement during difficult times when I started my PhD, to Olena Kravchuk for statistical support, to Maarten van Helden for the help with field experiment designs, and to Phillip John Earl for teaching me how to propagate vines. A special thanks to the following viticulturists, grape growers and vineyard managers for their advice, support, access to resources and to their vineyards: Ben Lacey, Matt Hatwell, James Hooks and Nick Dry. iv A big thank you to all of my lab-mates and friends for their friendship, encouragement and support, especially Feng Yi and Mary Joy Retallack for their invaluable help with the insects and experiment designs, Hue Thi Dang, The Duc Ngo, and Thang Viet Lai for assisting during field work, Trung Quang Do for providing the initial wealth of knowledge on the DNA sequences as well as assisting with field experiments and Tan Thanh Dang and Phuong Thi Nguyen for taking care of my son during time when I was busy with my field experiments. Last, but not least, to my dearest parents, sisters and brothers, my wife, Hang Hoang, and my son, Duy Bui, words would never be enough to express how thankful I am to your love, support and encouragement. v CHAPTER ONE General introduction and literature review 1 1. General introduction Regulation of crop insect pests by their natural enemies is an important ecosystem service that can support sustainable crop production while reducing the need for costly agrochemicals and associated environmental and human health concerns (Bianchi et al., 2006; Wyckhuys et al., 2013). Providing limiting resources to natural enemies through habitat manipulation as a form of conservation biological control can enhance both diversity and the ecosystem service they provide. At the field-scale, provision of floral resource plants is a common tactic to enhance local beneficial arthropods by providing them with plant-provided