Nutritional ecology of farmland bee larvae under a changing climate

Bagnall, Toby Euan

Abstract

1. Bees are a major component of a healthy ecosystem, pollinating almost all globally important crops and flowering plants. Pollinator numbers are dropping drastically however, with human-induced landscape change and an enhanced greenhouse effect partially at fault. Effects of a changing nutritional landscape are evident in adults of pollinating species but information about their offspring respond is limited. The larval stages of social species are difficult to monitor however, solitary bees both outnumber and outperform social bees as pollinators.
2. Osmia bicornis is a species of mass-provisioning solitary bee that construct tube like nests with individual cells meaning larval nutrition can be manipulated and monitored. With this study I aimed to understand; (1) whether bees detect and respond to changes in the nutritional composition of food and (2) does a changing climate affect their ability to do so? I reared O.bicornis larvae under different ambient temperatures (15°C, 20°C, or 25°C), providing one of 6 fixed artificial diets (3 Protein:Carbohydrate ratios at 2 concentrations). Larvae could only control how much of the diet they consumed so I assessed macronutrient consumption, and fitness across groups under the Geometric Framework for Nutrition.
3. Larvae controlled carbohydrate consumption to meet an intake target while tolerating unmonitored protein consumption unless developing in 25°C where the opposite is true. Larval weight gain and time to death were maximised with high protein intake even while controlling carbohydrate intake and this effect was stronger with high diet concentration.
4. My study shows O.bicornis larvae carefully control carbohydrate intake in natural conditions but under predicted temperature rise protein consumption was linked to their time to death. High carbohydrate intake is linked to overwintering success however, beyond optimal temperatures larvae may be delaying diapause in favour of consuming protein to deal with the new nutritional requirements.

Citation

Bagnall, T. E. (2019). Nutritional ecology of farmland bee larvae under a changing climate. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4222825

• Thesis Type: Thesis
• Deposit Date: Feb 22, 2021
• Publicly Available Date: Feb 23, 2023
• Keywords: Biological sciences
• Public URL: https://hull-repository.worktribe.com/output/4222825
• Additional Information: Faculty of Science and Engineering, The University of Hull
• Award Date: Sep 1, 2019