Bee-Lines, the magazine of the NBKA distributed quarterly to members.
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Intelligence v chemical responses in honey bees
When considering the complex organisation of a honey bee colony, the bees appear
to be showing intelligent behaviour.
However, much behaviour is governed not by intelligence, i.e. the ability to acquire
and apply knowledge and skills, but by
chemical responses. These chemical responses are produced by pheromones: a chemical
or mixture of chemicals released by a bee that affects the behaviour or physiology
of other bees. They may cause rapid changes in behaviour e.g. The alarm pheromone
quickly engages other bees to defend, or long-term changes in both behaviour and
physiology e.g. the brood pheromone suppresses worker’s ovary development.
Examples of honey bee pheromones:
Alarm pheromones. The Koschevnikov gland near the sting shaft releases an alarm pheromone
containing more than 40 components including iso-pentyl acetate. They are highly
volatile and smell like bananas. They attract other bees to
sting. The solvent in aftershave or perfume is similar to iso-pentyl acetate and
will elicit the same response.
It was thought that another alarm pheromone was 2-heptanone released by the mandibular
glands. However, it has been determined that bees use it to anaesthetise and paralyze
intruders – bees sink their mandibles into their opponents and emit 2-heptanone into
the lesion to numb the area. The bees are then able to remove the intruders from
the hive, which gives protection from their main enemies, wax moth larvae and varroa.¹
Beeswax pheromone affects intensity of hoarding behaviour.
Brood recognition pheromone is produced by larvae and pupae and helps nurse bees
distinguish between worker and drone larvae and pupae. It also inhibits development
of ovaries in workers.
Diploid drone cannibalism pheromone, produced by diploid drone larvae, causes workers
to eat diploid drone larvae preventing the colony rearing diploid drones.⁴
Drone pheromone enables drones to form a congregation area.
Dufour’s gland pheromone (‘alkaline gland’) only occurs in females i.e. Queens and
workers. It is not clearly understood. It is said to be responsible for retinue formation
around the queen³ and allows worker bees to distinguish between eggs laid by a queen
and those laid by workers. The composition of the pheromone changes as a worker evolves
into a laying worker.
Egg marking pheromone allows worker bees to distinguish between queen-laid and worker-laid
Faecal pheromone is produced by virgin queens. Fights between virgin queens or virgin
queens and workers are sometimes resolved when virgin queens squirt faeces on the
opponents. Workers covered in pheromone-laced faeces retire to groom; virgin queens
covered in faeces are ignored by the workers.
Footprint pheromone is secreted from the workers’ feet and is attractive to other
bees. It may help foragers locate a good food source and aid finding the hive entrance.
Forager pheromone (worker pheromone). Ethyl oleate is released by older forager bees
to slow the maturing of nurse bees to keep the ratio of nurse bees to forager bees
in the balance that is most beneficial to the hive.
Nasanov gland pheromone. Workers expose the gland located between the sixth and seventh
abdominal tergites and by fanning send the scent into the air. It is used to attract
nest mates to the hive entrance, a clustering swarm or a food source and attracting
a swarm to a nesting site. The smell of the Nasonov pheromone, including geraniol,
citral, nerolic acid and geranic acid, can often be detected in the air.
Tarsal (Arnhart gland) pheromone is similar to the footprint pheromone but is secreted
by the queen. It is deposited on the surface of the comb and is believed to delay
or prevent queen cell construction – it diminishes as the queen ages.
Tergite pheromone is produced by all the bees in the hive, but the composition and
amount varies with the type of bee. Virgin queen’s tergite pheromone is believed
to be related to fighting among virgin queens.
Queen mandibular pheromone (‘Queen substance’) regulates social behaviour, swarming,
mating and suppression of laying workers. It is spread throughout the hive by the
workers alerting colony members that the colony is queen-right and operating normally.
The most important components are:
9-oxodec-2-enoic acid (9-ODA) inhibits queen rearing as well as ovarian development
in worker bees, strong sexual attractant for drones when on a nuptial flight, critical
to worker recognition of the presence of a queen in the hive.
9-hydroxy-2-enoic acid (9-HDA) promotes stability of a swarm.
Queen retinue pheromone encourages workers to groom and feed the queen and causes
a retinue of attendants to surround and care for her.
A pheromone affects the behaviour of another individual of the same species. A pheromone
that affects the behaviour of individuals of a different species is called a kairomone,
used by parasitic or predatory insects to locate their hosts or prey. Varroa destructor
and Apis mellifera are different species. Varroa uses the odour produced by the honey
bee to find a host.
Rusty Burlew, Honey Bee Suite for permission to use her article on pheromones.
1. Honeybee Bites Can Act As Anesthetics: Medical News Today, 17 Oct. 2012. 2. www.honeybee.drawwing.org/book/dufour’s-gland