Plants for Pollinators

: Assessing the Ability of "Pollinator Friendly" Annual Seed Mixtures Designed for Gardens and Amenity Space to Support Wild Pollinators

Abstract

Concerns over wild pollinator declines have increased public motivation to purchase pollinator friendly plants and seed mixtures for gardens and amenity space. Ornamental annual seed mixtures are often described by the manufacturers as “pollinator friendly”, yet very few studies have scientifically tested these claims. The overall aim of this thesis was to assess the ability of ornamental annual seed mixtures to support wild pollinators and identify how mixtures could be improved. Pollen metabarcoding has been highlighted as an important methodological tool for assessing patterns of floral resource use and was used in combination with observational surveys and network analysis to explore patterns of floral resource use. In chapter one, four ornamental “pollinator friendly” annual seed mixtures were trialled for their ability to attract a diversity of wild pollinators. Findings revealed that only a small proportion of plant species in mixtures were visited by wild pollinators and none of the mixtures were very attractive to solitary bees. Chapter two explored the overall breadth and composition of floral resources used by wild pollinators across all seed mixtures and within the surrounding landscape. Patterns in floral resource use were investigated at the level of the overall network, species, and individual, using pollen metabarcoding and quantitative network analysis. Previous studies have found that floral constancy is a common trait displayed amongst individuals, though in the present study this was not found to be the case. In the third chapter, an evidence-based plants for pollinators recommendation list were systematically collated from peer-reviewed literature. Plant species that were identified, included species which are not currently used in annual ornamental mixtures and may have the potential to enhance them. Overall, the thesis highlighted the need and potential to enhance ornamental annual mixtures to support a greater diversity of wild pollinators and revealed important insights into the structure of plant-insect interactions within these mixtures.

Date of Award	2021
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Natasha De Vere (Supervisor), Peter Dennis (Supervisor) & Gemma Beatty (Supervisor)