Next-generation colony weight monitoring: a review and prospectus

Healthy honey bee colonies follow predictable patterns of weight change through the season, gaining weight when resources are abundant and losing weight during periods of scarcity. Divergence from this pattern can indicate trouble in the colony, necessitating beekeeper intervention. While colony weight monitoring has long been used to evaluate colony progress and diagnose potential problems, research has been limited by the labor associated with manual weight measurements. The introduction of next generation colony weight monitoring permits the collection of hive weight data continuously and remotely, enhancing the range of questions that can be answered with these data. However, there is currently no central guide for researchers aiming to use hive scales in their research. Here, we review the literature and describe current methods used to process and analyze within-day, or diel, and seasonal colony weight changes. Diel weight dynamics are based around the circadian rhythm of the colony, resulting from the departure and arrival of foragers and the intake, consumption, and dehydration of food stores. Seasonal weight dynamics can be used to assess colony survival and productivity, often in relation to large-scale patterns of climate, landscape, and floral resource phenology. In addition to describing methods, we highlight future applications of hive weight monitoring, including monitoring weight across ecological gradients and physiological time, coupling of weight monitoring with other colony monitoring techniques, and the practical use of weight monitoring in commercial beekeeping operations. This paper serves as a tool for those wishing to conduct research using colony weight monitoring, and guides the future of remote weight monitoring in honey bee research.