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Most beekeepers have seen trophallaxis in action. Commonly, two or three bees stand head to head with their tongues extended. Sometimes their antennae are active too, probing and examining the mandibles of another bee.
What is trophallaxis?
Trophallaxis is the transfer of food and other substances between colony members. The process of transfer varies with the substance. For example, information exchange with pheromones can move like traffic on a two-way, flowing in both directions. In other cases, the information flow may be in one direction only.
Food exchange can go two ways when bees are trying to communicate the need for supplies, or it may go only one way, as when a forager with a full honey stomach (or crop) regurgitates her load of nectar and passes it to a house bee for processing.
How many types of trophallaxis do honey bees use?
Honey bees use several types of trophallaxis, each with a specific purpose. Some of the most important types of trophallaxis include:
- Worker-to-worker: This is the primary form of trophallaxis in a colony. It is an exchange of liquid food, such as nectar or water, between worker bees. This process helps to disseminate information about the location, availability, and quality of food resources. Pheromones passed between bees are also important for social bonding and bee health.
- Unloading: This is the transfer of nectar or water from foraging bees to house bees through regurgitation. It is the form of trophallaxis used to ripen nectar into honey before it is stored in the cells of the honeycomb.
- Queen-worker trophallaxis: This is the exchange of food and information between the queen bee and worker bees, which occurs during the queen’s egg-laying period. When the queen’s pheromones are distributed throughout the workforce, the bees know their queen is active and healthy.
- Nurse-forager trophallaxis: This is the exchange of food and information between nurse bees and forager bees, which helps foragers understand the level of need in the brood nest.
- Drone-worker trophallaxis: This is the direct provision of food from worker bees to drones. It occurs whenever drones are present in the colony.
Bee-to-bee information transfer
This type of information transfer helps the colony with decision-making and social structure. For example, trophallaxis aids in:
- Acquisitions: Samples of newly discovered food sources can be passed among the bees so they can evaluate them firsthand, much like we examine a sample of food from a vendor’s table. “Oh, delicious!” we say. “Let’s buy some.” Or, “No, I’ll pass.”
- Queen health: Levels of queen pheromone tell the workers about queen health. When levels drop, the worker may build supersedure cells.
- Social bonding: The exchange of food and pheromones helps to strengthen the social bonds within the colony. These bonds are essential to maintain a cohesive workforce.
- Maintenance of colony health: Trophallaxis helps to ensure that all members of the colony have access to the nutrients and information they need to stay healthy. In times of dearth, food can be shared equally among all the bees. In addition, sick or weak bees can be eliminated from the colony.
- Colony sanitation: Word can be passed around that debris or other contaminants and parasites need to be removed from the hive.
How food is transferred within the hive
Food transfer can occur when bees are hungry or when nectar needs to be processed. It usually begins with a house bee asking for a load of food. She does this by protruding her proboscis (tongue) toward a nectar-laden bee. The donor bee regurgitates a drop of food from her honey stomach and cradles it between her mandibles so the receiving bee can slurp it up with her tongue.
During the exchange, which can last either seconds or minutes, the bees communicate by touch with their antennae. Sometimes the donor bee offers the drop of food before another bee asks for it, but the actual transfer works the same way.
Although drones receive both food and water from workers, they do not participate in information exchange the way workers do. Some people separate drone feeding (or one-to-one feeding) from true trophallaxis, while others include it as a subset of trophallaxis.
The same occurs with queen feeding. The queen is fed directly by workers often without queen-to-worker exchange. But separating queen feeding from “true trophallaxis” is murky when you consider that workers can pick up queen pheromones during trophallaxis and distribute them to other colony members. For simplicity, I like to think of any oral bee-to-bee transfer as trophallaxis.
How often does trophallaxis occur within a colony?
The frequency of trophallaxis varies depending on the size and health of the colony, the availability of food, and the time of year. On average, trophallaxis can happen multiple times per minute and may involve many individuals.
During times of plenty, when the colony is strong and there is an abundance of food available, trophallaxis may occur less frequently. But when resources are scarce or the colony is weaker, such as during the winter or during a nectar dearth, trophallaxis may occur more frequently because the bees work hard to share and distribute resources to every bee throughout the colony.
What other insects besides honey bees use trophallaxis?
Trophallaxis is a common behavior among social insects, although the exact method of food transfer can vary between different species. Other insects that use trophallaxis include:
- Ants use trophallaxis to transfer food and information between colony members. They also use it to share food with the queen and her offspring.
- Termites use trophallaxis to transfer food between workers and soldiers, and also to feed the queen and her offspring.
- Some wasp species use trophallaxis to transfer food between colony members, especially to feed the developing larvae.
- Bumble bees also use trophallaxis to transfer food and information between colony members, similar to honey bees.
- Some species of solitary bees use trophallaxis to share food with their offspring.
What is the downside to trophallaxis?
Unfortunately, trophallaxis can also spread disease throughout a colony, especially when pathogenic organisms reside inside the honey bee gut. It has also been implicated in the spread of viral and parasitic diseases. Nevertheless, trophallaxis is a vital part of honey bee biology that they cannot survive without.
Honey Bee Suite