Communication Without Sound
Ed Erwin
Beekeepers know that pheromones are the key to controlling all activities of the bees in the beehive. In 1959, the word pheromone was suggested in an article in Nature by two German scientists. The word pheromones comes from two Greek words: homan, to carry, and pherin, to excite.
Pheromones of the honey bee are a variety of chemical substance mixtures in varying percentages produced by the individual bee. The array of chemical compounds are released by 15 different glands located in different parts of the body. Each chemical pheromone is different and when excreted or secreted, they trigger responses from other bees.
These discharges are either a releaser pheromone, which have a short term effect with almost immediate behavioral response from the receiving bee, or a primer pheromone with long term effects which change the physiology and behavior of the recipient.
Pheromones are initially produced in a liquid form and transmitted to the other bees in the liquid form or as a vapor. Depending on the pheromone, they are either produced as volatile (evaporates easily at normal temperatures) or non-volatile (does not readily evaporate). The chemical messages are received principally on the bee’s 170 odor receptors (chemoreceptors) located on the antenna and other body parts, such as the feet.
The honey bee pheromone communication is one of the most complex and effective among insects. The worker honey bee is known to transmit over eight pheromones, which include: Alarm, Brood recognition, Drone, Dufour’s gland, Egg marking, Footprint, Forager, Nasonov and a few others. The queen honey bee produces a few of her own pheromones which include the Queen mandibular and Queen retinue.
Pheromones are the key factor in the way the queen, workers and drones communicate and coordinate the complex activities within the hive. They are important to all types of activities including foraging for resources, wax foundation construction, defending the hive, new queen development and swarming. Here are some of the key pheromones.
Alarm pheromone
When a honey bee stings another animal, it releases a chemical known as isopentyl acetate or alarm pheromones, which signals other bees to become defensive and attack the sting location. Two main alarm pheromones have been identified in honey bee workers.
The Koschevnikov gland is located near the sting shaft. It releases an alarm pheromone when a bee stings. This pheromone is made up of over forty highly volatile chemical compounds. When released, this pheromone attracts other bees to the sting location and all the bees begin defending the colony. The isopentyl acetate in the alarm pheromone smells like bananas.
The other alarm pheromone is released by the mandibular glands located on the head and can be a highly volatile substance. When honey bees are in their foraging stage (older worker honey bees) the mandibular glands produce an alarm pheromone. When the worker bees are younger and performing nursing tasks they produce a nutritional secretion called royal jelly from the mandibular gland, which along with pollen and honey is fed to larvae. If a larvae is fed only royal jelly the larvae will develop into a queen.
Smoke can mask the bees’ alarm pheromone. Most beekeepers know that the smoke works on bees by impeding their sense of smell and triggers their not being able to detect the alarm pheromone, their survival response. Second, most literature on the subject suggests that the smoke incites the bees to gorge themselves with honey in preparation of leaving the hive due to fire. However, Dr. Norman Gary, emeritus professor of entomology at the University of California, Davis, who has kept bees for more than seven decades and smoked thousands of hives during his career writes, “Bees react to smoke by fanning, motion, flight and immediately ingesting nectar and honey, and the smoke disrupts their defensive behavior.” In his observations, there was never any indication that bees left the hive area in response to smoke. Additionally, “migration of the colony away from the fire and smoke would be impossible because the queen is full of eggs and much too heavy to fly. Consequently, a colony that migrated from a fire could not survive without their queen.”
Brood Recognition Pheromone
When the bee colony is raising larvae and pupae, they emit a brood recognition pheromone from their larval salivary glands. This pheromone acts both as a primer and releaser. Brood cannot survive without the constant care and feeding of nurse bees. This pheromone also helps nurse bees differentiate between female worker bee and drone larvae and pupae development. When it is time for the developing pupae to develop a cocoon the silk for the cocoon is produced from the salivary glands. This pheromone also hinders worker bees ovarian development and prevents worker bees from bearing offspring.
Drone pheromone
In the Spring, the queen begins the production of drone (male) bees from unfertilized eggs whose purpose is to mate with virgin queens from other hives. Drone bees produce and emit a pheromone from their mandibular gland to attract other drones to the drone congregation area (DCA) to mate with virgin queens. It is also believed that the virgin queens follow this pheromone scent when locating the drone congregation area. The drones are generally concentrated in area between 100 to 770 feet in diameter and 50 to 130 feet above the ground.
Egg Marking and Dufour’s pheromone
The queen produces the egg marking pheromone that has several chemical compounds unique to the queen. Because both the queen and workers can lay eggs these compounds allow workers to differentiate between eggs not deposited by the queen and they will destroy the eggs without the marking pheromone. It is believed that the egg marking pheromone is associated with the Dufour’s gland. The Dufour’s gland opens into the dorsal vaginal wall and is named after the French naturalist Léon Marie Dufour. This pheromone is composed of 24 different alkaline chemicals and lets the workers know when the colony is “queenright” or if the colony is queenless.
Tarsal Pheromone
Also known as the footprint pheromone and trail pheromone, the tarsal pheromone is an oily, colorless, chemical secretion, with a low volatility. It is deposited by queens, workers and drones as they walk on surfaces. The pheromone glands are located on the fifth tarsomere of all six legs. Queens secrete 12 compounds, workers secrete 11 and drones one. This attractive order affects the behavior of other workers, particularly in locating the hive entrance, nectar and other food sources. When bees are standing at the entrance of the hive with their abdomens raised and fanning their wings, they are helping returning foraging bees in orientation and location of the hive. As the queen walks on the comb, she deposits her tarsal pheromone, which inhibits queen cell construction, and therefore less motivation for the bees to swarm.
Queen Signal
The queen honey bee controls the main colony functions by means of a complex chemical blend of pheromones produced by different glands known as “queen signal”. This signal is a primer pheromone causing behavioral modifications in the worker bees and establishes social hierarchy and preserves the queens dominance in producing offspring for the hive. The queen signal is constant and if it decreases, or is absent, the worker bees will begin feeding larvae royal jelly within 24 hours in order to produce a new queen for the hive.
Amazingly, the communication within the hive is conducted by the emittance and receipt of pheromones – all done in the dark.
Ed Erwin
Beeharmony.org
Beeharmonyorg@gmail.com
281-222-0934
Executive Director of Bee Harmony
Certified Master Beekeeper – University of Montana
Director of the Mentee/Mentor Program of the Montgomery County Beekeepers Association
