The nutritional ecology of farmland bees : behavioural and community approach

Austin, Alexander James

Biological sciences
May 2019

Thesis or dissertation


Rights
© 2019 Alexander James Austin. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.
Abstract

Nutritional degradation, attributed to agriculture, is a primary driver of bee declines, yet we know very little about bee larval nutrition. How larvae deal with nutritional variation in their provisions remains relatively unexplored. Additionally, the nutritional requirements of adult and larval bees differ, yet such a distinction is rarely considered when investigating bee-flower communities. Using the Geometric Framework I ask (a) whether solitary bee larvae (Osmia bicornis) regulate their nutrient intake, and (b) whether the importance of macronutrients change across development. Second, I investigate (a) how bee and host plants communities change within a flight season on organic and conventional farms, and (b) how bees’ foraging decisions shape their interaction networks. Specifically, using DNA metabarcoding of pollen, I separate larval- and adult-focussed foraging interactions. I show that larval bees prioritise carbohydrate over protein, but that the importance of individual macronutrients shifts from protein to carbohydrate throughout development. I also demonstrate that larvae regulate lipid intake, a macronutrient often overlooked in bee nutrition. I show that organic farms support higher abundances, but not higher diversity, of plants and bees, and that nutritional resources vary more with season than farming practice. Lastly, I show that bees forage differentially for their offspring, highlighting the need to consider both adult and larval nutrition when managing landscapes for bees. These findings highlight the importance of a holistic view of bee nutrition. Larval bees are able to regulate their nutritional intake, suggesting a capacity to deal with nutritional variation. However, this ability is limited, with bees perhaps being vulnerable to undetectable changes to their nutritional environment. Nutritional resources also differ phenologically across farming practices, highlighting the need to address key nutritional gaps for bees. Finally, understanding that bee parental care shapes the way bees interact with their environment is essential to providing quality floral resources that address both adult and larval needs.

Publisher
Department of Biological & Marine Science, The University of Hull
Supervisor
Gilbert, James; Lawson Handley, Lori
Qualification level
Doctoral
Qualification name
PhD
Language
English
Extent
8 MB
Identifier
hull:17344
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