Food for thought: could the queen's egg-laying rate in the BEEHAVE honey bee model emerge from the effects of brood pheromones, weather conditions, and pollen availability?

The BEEHAVE honey bee model is widely recognised for its ability to analyse the impact of local land use, including pesticide use, weather conditions, mite infestations, and beekeeping practices, on the risk of colony loss. However, it is based on an imposed egg-laying rate that represents only average conditions in Central Europe while also being the main driving factor in colony dynamics. A modified version of the model, called BEEHAVE-PPE (Pollen Pheromone Egg-laying), was developed, in which positive feedback between pollen foraging and the egg-laying rate was implemented. It was assumed that daily pollen foraging depends not only on weather conditions but also on brood size, brood pheromones, and temperature. The six parameters of the new BEEHAVE-PPE module were calibrated using demographic and weather data from a bee colony monitoring area in France. This produced realistic colony dynamics under average weather conditions but not under prolonged periods of adverse weather that prevented foraging. Although the model is based on unverified heuristic assumptions regarding brood pheromone production and dynamics, the results suggest that it is plausible that the egg-laying rate in honey bee colonies is influenced by local weather conditions and feedback from the brood. The new version, BEEHAVE-PPE, is not intended for direct use but rather to stimulate empirical research on queen egg-laying, brood pheromone signalling, and theoretical work on colony feedback dynamics.