Using the Beehave Honey Bee Model Across Climates: Emerging Instead of Imposed Queen Egg-Laying Rate and the Influence of Weather Conditions, Pollen Storage and Brood Size

Abstract

Multiple stressors threaten honey bees and increase the risk of colony mortality. Empirical studies to determine the relative importance of stressors and critical stress levels are not feasible because most stressors and colony characteristics cannot be controlled. Modelling of honey bee colonies can help to fill this gap. The BEEHAVE model is well acknowledged to analysis the impacts of local land use, including pesticide use, weather, mite infestation and beekeeping practices on the risk of colony mortality. However, it is based on an imposed egg-laying rate which is only representative of average central European conditions and at the same time the main driving factor for the colony dynamics. We developed a modified version, BEEHAVE-PPE (Pollen Pheromone Egg laying), where the maximum egg-laying rate depends on pollen storage and intake. We assumed that daily pollen foraging, and thus pollen uptake, depends not only on the weather, but also on brood size, brood pheromones, and temperature. BEEHAVE-PPE was successfully calibrated using demographic and weather data from a bee colony monitoring area in France. While our model is based on yet unverified assumptions concerning brood pheromone production and dynamics and therefore needs further empirical confirmation, the results indicate that it is possible to let the egg-laying rate in honey bee colonies emerge from the local climate and the feedbacks from the brood.

Keywords: honey bees, multiple stressors, egg-laying, brood pheromones, emergence, BEEHAVE