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Title: Perimeter land management for pollination and pest control services in apple orchards
Author: Joslin, Emma
ISNI:       0000 0004 8509 9977
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2019
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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.
Supervisor: Poppy, Guy Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available