University of Southampton Research Repository
Total Page:16
File Type:pdf, Size:1020Kb
University of Southampton Research Repository Copyright © and Moral Rights for this thesis and, where applicable, any accompanying data are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. This thesis and the accompanying data cannot be reproduced or quoted extensively from without first obtaining permission in writing from the copyright holder/s. The content of the thesis and accompanying research data (where applicable) must not be changed in any way or sold commercially in any format or medium without the formal permission of the copyright holder/s. When referring to this thesis and any accompanying data, full bibliographic details must be given, e.g. Thesis: Author (Year of Submission) "Full thesis title", University of Southampton, name of the University Faculty or School or Department, PhD Thesis, pagination. Data: Author (Year) Title. URI [dataset] University of Southampton Faculty of Natural and Environmental Sciences Biological Sciences Perimeter Land Management for Pollination and Pest Control Services in Apple Orchards by Emma Joslin Thesis for the degree of Doctor of Philosophy June 2019 University of Southampton Abstract Faculty of Natural and Environmental Sciences Biological Sciences Thesis for the degree of Doctor of Philosophy Perimeter Land Management for Pollination and Pest Control Services in Apple Orchards by Emma Joslin Dessert apple orchards in the UK have successfully intensified their growing systems to enable a higher yield output per unit area. This agricultural intensification has allowed for more efficient crop management. However, this intensification has come at the detriment to space for non-crop vegetation in the orchards, attributed to sustaining invertebrate populations of pollinators and natural pest enemies with alternative resources and refuge. Therefore, the remaining populations of beneficial invertebrates in these systems might not be able to deliver sufficient or stable regulating ecosystem services such as pollination and pest control to the crop system. To address this concern, I firstly carried out a survey with a select group of top-fruit growers in my study region to understand the practices and perceptions surrounding existing non-crop vegetation in orchards. Non-crop trees were already in place on farms as hedgerow or windbreak structures; however, these had rarely been designed to support beneficial invertebrates. Furthermore, various blockers for annual wildflower adoption were identified. Therefore, this knowledge contributed to the design of a novel ecological experiment to enhance apple orchard edges with perennial lavender and thyme plants. The aim was for these plants to provide successional floral resources in close vicinity to the crops to sustain pollinator populations after the mass apple bloom, whilst not deterring natural enemy populations to thrive on-site during the apple-growing season. Orchard edges with either a mixed lavender and thyme treatment, or a lavender treatment, successfully sustained wild pollinators, such as bumblebees, in the orchards over the late summer months. The wild bee visitation rate to apple flowers in the spring also increased in orchards with a mixed orchard edge treatment. Although no repellent effects of lavender and thymes on natural enemies were found; the effects on ground or tree dwelling natural enemy populations remain uncertain due to sampling methods and agrochemical use. Aerial hoverfly abundances were higher in the orchards with a mixed lavender and thyme edge however, it would need to be confirmed that these were aphidophagous species before concluding that natural enemies with an aerial life stage, which relies on floral nectar or pollen provision, could benefit from this orchard edge enhancement. Apple yield and quality were both unaffected by orchard edge treatments in the first two years after establishment. However, pollinator exclusion experiments confirmed the necessity of pollinators to the apples to achieve good yields and quality. Therefore, any increase to wild bee abundances from the orchard edge treatments could potentially contribute stability to the pollination service delivery by buffering the natural fluctuations in pollinator populations and the potentially inconsistent pollination services from managed honeybees. This research shows how collaborating with the select group of growers that are responsible for non-crop habitat provision and management on farms in the study region can enable the development of novel alternatives to ensure that floral resource provision is available on-site for beneficial invertebrate populations. Table of Contents Table of Contents Table of Contents .......................................................................................................... i Table of Tables ............................................................................................................ vii Table of Figures ............................................................................................................ix Research Thesis: Declaration of Authorship ................................................................ xiii Acknowledgements ..................................................................................................... xv Definitions and Abbreviations .................................................................................... xvii Chapter 1 Literature Review ....................................................................................... 1 1.1 Intensive Agriculture and Biodiversity Loss ............................................................... 1 1.2 Ecosystem Services ..................................................................................................... 1 1.2.1 What are ‘ecosystem services’? ......................................................................... 1 1.2.2 Biodiversity and ecosystem services .................................................................. 2 1.2.3 Valuing ecosystem services for an ‘ecosystem services approach’ ................... 3 1.3 Pollination and Pollination Services ........................................................................... 3 1.3.1 Importance to agriculture .................................................................................. 3 1.3.2 Pollinator declines and suggested strategies ..................................................... 4 1.4 Pests, Natural Enemies and Biological Control Services ............................................ 6 1.4.1 Importance to agriculture and suggested strategies ......................................... 6 1.5 Ecological Intensification ............................................................................................ 8 1.6 Non-crop vegetation in agro-ecosystems ................................................................ 10 1.6.1 European agri-environment schemes .............................................................. 10 1.6.2 ‘Hedgerows’ ..................................................................................................... 11 1.6.3 ‘Windbreaks’ .................................................................................................... 11 1.6.3.1 The many benefits of hedgerows and windbreaks: .............................. 12 1.6.3.2 How hedgerows and windbreaks can affect beneficial species populations: ........................................................................................... 12 1.6.4 Wildflower provision ........................................................................................ 13 1.7 UK Apple Production ................................................................................................ 14 i Table of Contents 1.8 Growers’ decisions and opinions on non-crop vegetation in apple and pear orchards for pest control and pollination services .................................................. 18 1.8.1 The importance of incorporating farmers views into ecological research ...... 18 1.8.2 Top-fruit grower survey and interview implementation ................................. 20 1.8.3 Findings from the trop-fruit grower surveys and interviews .......................... 23 1.8.3.1 Top fruit production on the respondents’ farms .................................. 23 1.8.3.2 Drivers of crop loss ................................................................................ 26 1.8.3.3 Invertebrate pest damage and pest management strategies .............. 28 1.8.3.4 Non-crop vegetation in orchards – current practices and perceptions 33 1.8.4 Conclusions about current provisions, decisions and opinions on non-crop vegetation in top-fruit orchards for pest control and pollination services ..... 42 1.9 Thesis Aims and Objectives ...................................................................................... 43 Chapter 2 Planting aromatic herbs along apple orchard edges can increase wild pollinator abundance ................................................................................ 47 2.1 Abstract .................................................................................................................... 47 2.2 Introduction ............................................................................................................. 48 2.3 Methods ................................................................................................................... 51 2.3.1 Study area .......................................................................................................