Causes and Consequences of Egg Size Variation in the Honey Bee

: Apis mellifera

Abstract

Honey bee (Apis mellifera) eggs show variation in size and queens are known to increase egg size during times of nutritional stress. Humans are changing the nutritional landscape available to bees, yet how exactly this affects the relationship between land-use and honey bee egg size is unknown. It is also unknown whether this change in egg size has downstream consequences for the worker. Here, we test if egg size varies between rural vs. urban areas in southwest England. Egg size in rural areas was significantly larger than in urban areas indicating that honey bees are more nutritionally stressed in rural areas and experience better conditions in urban areas. Accordingly, the percentage cover of suburban land had a positive impact on colony weight change, which in turn predicted egg size negatively. Experimentally inducing queens to lay larger eggs showed only a weak association between egg size and worker size. However, RFID data suggested that bees from larger eggs were more active and performed 23.8% more foraging trips, leading to a greater time spent foraging overall. There was no significant effect of egg size on lifespan.
Our data indicate that egg size manipulations are an adaptive trait used by the queen to increase colony foraging activity during periods of colony stress. Our work provides
valuable information on how A. mellifera bees may use egg size to cope with fluctuations in floral resources and anthropogenic land-use change.

Date of Award	21 Oct 2024
Original language	English
Awarding Institution	University of Bristol
Sponsors	The British Beekeepers Association
Supervisor	Christoph Grueter (Supervisor) & Rajbir Kaur (Supervisor)