Opening a hive to find it filled with drones can be disappointing sometimes. The colony could be ready to swarm, the queen may have run out of sperm in her spermatheca, or the hive may be queenless with a laying worker. Although these situations may not be ideal, it is important to remember that honey bees need drones to mate with the queens for subsequent brood production.
The Bees Keep Droning On
While workers and queens come from fertilized eggs, drones
come from unfertilized eggs (Rangel & Fisher, 2019). So, in the case of an
old queen running out of sperm or a queenless hive with a laying worker, the
only brood reared would be drones. The development of drones from egg to
emerging adult is approximately 24 days, while it is 16 days for queens and 21
days for workers (Rangel & Fisher, 2019). It takes a drone approximately 16
days to sexually mature, but after 28 days they are less suitable for mating,
and the average life span is 55 days (Rhodes, 2002).
Rearing drones is costly for the colony because drones do
not participate in any aspects of colony maintenance, other than reproduction,
and they depend on the nurse bees to raise them as larva and feed them as
adults (Rangel & Fisher, 2019; Rhodes, 2002). The worker bees are responsible
for cleaning the hive, tending to brood, nourishing the bees, homeostasis of
the hive, producing wax, foraging, and communicating all these tasks with other
workers (Hrassnigg & Crailsheim, 2005). The drones lack hypopharyngeal
glands (brood food glands), wax glands, they have a shorter tongue, smaller
mandibles, smaller mandibular glands, and a slenderer honey stomach compared to
workers (Hrassnigg & Crailsheim, 2005). Therefore, drones do not have the
necessary anatomy for the workers’ jobs, but they have anatomical and
physiological differences to aid in reproduction. A drone must find an airborne
queen at a drone congregation area and compete with hundreds to thousands of
other drones to be successful, which is why they have adaptations for strong flying,
elaborate mating organs, and strong sense organs for locating queens (Hrassnigg
& Crailsheim, 2005). Some examples include the 13,000 facets in a drone's
eyes compared to 400-6300 in worker's eyes and the 30,000 chemoreceptors in
drones compared to 2400 in workers (Sammataro, 2021).
Honey bee mating occurs in a drone congregation area (DCA),
which is an area where sexually mature drones congregate and wait for virgin
queens to arrive. DCAs are in the same place from year to year and do not need
a queen present for their formation (Sorel et al. 2018). They are typically
formed in areas protected from winds, with very few obstacles within the DCA
that could interrupt mating flights. In optimal environmental conditions,
drones will patrol a DCA 100 to 200 meters wide at an altitude of 5 to 40 meters.
More than 96% of drones in a DCA come from apiaries located within 900 meters
(Sorel et al, 2018). When a queen enters the DCA, a swarm of drones pursue her
in a comet shaped formation, until she mates with an average of 12 drones (although
up to 50 have been recorded), but only 0.5% of drones in the DCA successfully
mate with the queen (Sorel et al. 2018).
When there is an overabundance of drones, it is important to make sure that it is not due to an unproductive queen or queenlessness. If there are drones due to one of these issues, they can be fixed by requeening the colony. In temperate climates and under normal conditions, drone rearing only takes place during the part of the season when there is plenty of resources available and a large worker population (Rangel & Fisher, 2019; Rhodes, 2002). When there is a lack of resources and colder ambient temperatures, the drones are starved out by the nurse bees and forcibly removed from the hive (Rhodes, 2002). Although it may be alarming to see many drones in the colony, they may be needed for rearing queens and workers, and if they are not needed, they will be evicted by the existing workers.
Written by John MacDonald, ATTTA Seasonal Apiculturist - johnmacdonald@perennia.ca
Connecting with ATTTA Specialists
References:
Hrassnigg N, Crailsheim K. 2005. Differences in drone and
worker physiology in honeybees (Apis mellifera). Apidologie 36(2005):255-277.
Rangel J, Fisher A. 2019. Factors affecting the reproductive
health of honey bee (Apis mellifera) drones – a review. Apidologie
50(2019):759-778.
Rhodes J. 2002. Drone honey bees – rearing and maintenance.
NSW Agriculture.
Sammataro S. 2021. A beekeeper’s handbook: fifth edition.
Cornell University Press.
Sorel A, Martin G, Houle E, Giovenazzo P. 2018. Finding
DCA’s - Where do we go? Bee Culture: The Magazine of American Beekeeping.