It is well known that during the spring months honey bees are starting to swarm. During the early part of the season, honey bees swarm due to overcrowding in the hive. However, did you know that there are other causes for honey bees to swarm? Also, we can recognize the signs of a hive ready to swarm and predict when swarming will occur. This week’s blog will explain how and why swarming occurs, and also how we can predict when this event will occur.
Honey Bee Biology Series: The Natural Conditions of Swarming
Swarming is the natural mechanism of colony reproduction. The colony divides, and leaves daughter queens to hatch and perpetuate the hive. Most often swarming is triggered by hive congestion, low potency of the queen mandibular pheromone, and minimal cell space for a queen to lay eggs. But swarming can also be triggered by a failing queen or a lack of ventilation in the hive (Winston 1987).
Once the hive has been triggered to swarm, worker bees will build swarm cells at the base of comb. Additionally, the queen lays drone eggs to carry on her genes. Next, the existing queen will lay eggs in the swarm cells or worker bees will move fertilized eggs into the cells (Winston 1987). When beekeeping, one way to recognize a hive that is ready to swarm is the presence of swarm cells. Swarm cells are found hanging at the bottom of the frame, whereas cells produced during an emergency requeening or supersedure are typically found in the middle of the frame. There are several other signs that a hive is ready to swarm, including: rapid growth of the worker bee population, drone rearing, bound broodnest, restlessness of existing queen, reduced laying, and field bees are less active (Winston 1987).
Once the hive is ready to swarm (typically when new queens have been reared in swarm cells) queen piping (tooting and quacking) occurs between the new queens and the original queen. Upon piping, workers can decide to protect the responding new queens by feeding them or they can ignore piping and let emerging queens find and kill other queens (Simpson and Cherry 1969). Recent research suggests that piping serves as information to the workers about the number of capped and released queens in order to decrease the rate of competition (Ramsey et al. 2020). Regardless of the signal function, it still indicates the presence of a virgin queen in preparation for a swarm.
When a new queen emerges two different scenarios can occur. The first scenario is that a new queen will take over the original colony, and the original queen will leave with a group of forager bees to find a new hive. The second scenario, known as an ‘afterswarm’, is where the population is still too large and the new queen also leaves the hive with a portion of the colony. This process may repeat until the population is a suitable size for the hive.
Swarming requires a lot of preparation and the signals used can be olfactory as well as acoustic or vibrational (Rangel and Seeley 2008; Schlegel et al. 2012). Vibration signals are indicative of honey bee behaviour and overall health of the colony. They can be caused by honey bees contracting their thoracic wing muscle and pressing their vibrating bodies against the wax of the hive or another bee (Kirchner, 1993).
Automatic monitoring systems are an emerging tool for beekeepers to determine swarming preparation in a colony. The visual analysis of sound emitted by honey bees is a useful method for swarming detection. A study done by Ramsey et al. (2020) was able to successfully find a signal indicative of swarming, and was able to trigger accurate pre-swarming alarms. This work was originally done by Bencsik et al. (2011) where the honey bee swarming process was identified by analyzing the time course of hive vibrations.
Overall, swarming is an important way for honey bees to spread to new locations and increase in numbers. Additionally, for a swarm to be successful requeening must occur. Next week’s blog will be exploring a different requeening scenario known as a supersedure.
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Ramsey, M.T., Bencsik, M., Newton, M.I. et al. 2020. The prediction of swarming in honeybee colonies using vibrational spectra. Sci Rep.
Rangel, J., Seeley, T. 2012. Colony fissioning in honey bees: size and significance of the swarm fraction. Insectes Sociaux. 59 (4): 453 – 462.
Schlegel et al. 2012. Beeping and piping: characterization of two mechano-acoustic signals used by honey bees in swarming. Naturwissenschaften.
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Simpson, J., Cherry, S.M. 1969. Queen confinement, queen piping and swarming in Apis mellifera colonies. Anim. Behav. 17: 271 – 278.
Winston, M.L., 1987. The biology of the honey bee. harvard university press.