Insects rely on chemical signals called pheromones to communicate with one another. These substances are used for a variety of reasons, from attracting mates to warning others of danger. This raises the question of whether bees, known for their social structures, release such chemical warnings when they are threatened or killed.
Understanding Bee Alarm Pheromones
Many social bee species, most notably honeybees, release alarm pheromones when they are seriously injured or crushed. When a honeybee stings, it leaves its barbed stinger embedded in the skin. This act is fatal to the bee and ruptures the venom sac and associated glands, releasing a plume of alarm pheromones.
The primary chemical component released from the bee’s sting apparatus is isopentyl acetate, a compound often described as having a scent similar to bananas or pears. Another alarm chemical is 2-heptanone, which is produced in the bee’s mandibular glands and can be released when a bee is agitated or crushed, even if it doesn’t sting. This defensive strategy is not universal, as many solitary bees do not possess this same complex alarm system.
The release of these pheromones is a direct consequence of a bee defending its colony. Whether through stinging or by being crushed, the release of these chemicals serves as a final warning to its hive mates.
How Bees Respond to Alarm Signals
Nearby bees detect these airborne alarm pheromones almost instantly through specialized receptors on their antennae. The introduction of these chemicals triggers an immediate and noticeable shift in the behavior of other worker bees. They become more alert, agitated, and exhibit defensive postures to confront the source of the danger.
This chemical signal can incite other bees to become aggressive and home in on the location where the pheromone was released. They will investigate the area, targeting the threat that provoked the initial bee. This can lead to a defense cascade, where the first sting encourages more bees to sting, each subsequent sting amplifying the chemical alarm.
The intensity of this defensive reaction can depend on several factors. A higher concentration of alarm pheromone, from multiple crushed bees, will elicit a stronger response than from a single bee. The colony’s temperament and proximity to the hive also play a role; a disturbance at the hive entrance will provoke a faster defense than one further afield.
Practical Tips for Human-Bee Encounters
Understanding the role of alarm pheromones can inform safer interactions with bees. If you kill a bee near a hive, it is wise to calmly and quickly move away from that area. Lingering where alarm pheromones have been released increases the likelihood of attracting other agitated bees.
Aggressively swatting at a bee is more likely to provoke a sting, which guarantees the release of alarm pheromones. A calm and slow retreat is a much better strategy when a bee is uncomfortably close. If you are stung, remove the stinger from your skin as quickly as possible because it can continue to pump venom and release pheromones.
After removing the stinger by scraping it out with a fingernail or a credit card, you should leave the immediate vicinity. This helps to distance yourself from the chemical signal marking you as a threat. Beekeepers often use smokers during hive inspections because the smoke masks the alarm pheromones, helping to keep the bees calm.