Queen temperature stress decreases sperm viability, queen performance, and colony productivity

The health and performance of honey bee queens is an important factor determining colony productivity and survival. The aim of this project was to evaluate whether exposing queens to high and low temperatures affected the viability of queen's sperm, queen performance, and colony productivity.
Objectives:
a) to monitor temperature in honey bee queen shipments, b) to evaluate the effect of temperature treatment on queen's sperm viability, queen performance, colony productivity and colony survival.
Methods: We monitored temperature of queen shipments using data-loggers. We then exposed queens to the observed temperatures and evaluated the viability of the sperm by fluorescent microscopy. Finally, in a 60 colony field experiment, we compared the performance of temperature-treated queens and controls and evaluated colony productivity and wintering survival of colonies headed by temperature-treated queens and controls.
Results and conclusions: Queens can be exposed to both high and low temperatures during shipment which reduces sperm viability. These temperature treated queens, however, were otherwise indistinguishable physically or behaviorally from non-treated queens.
In a field study of 60 colonies, we observed a dramatic decrease in queen performance and colony productivity in colonies headed by temperature-treated queens. These colonies had poor brood patterns, only half of the adult population, and only one-third of the honey production compared with control colonies. In addition, while no overwintering losses were observed in colonies headed by control queens, 61% of the colonies headed by temperature-treated queens perished over the winter.
These striking results are of importance to the beekeeping industry as they can guide future efforts to improve shipping conditions as well as guide management decisions to improve queen performance and colony productivity.