Honey Bee - Defense

Defense

All honey bees live in colonies where the workers will sting intruders as a form of defense, and alarmed bees will release a pheromone that stimulates the attack response in other bees. The different species of honey bees are distinguished from all other bee species (and virtually all other Hymenoptera) by the possession of small barbs on the sting, but these barbs are found only in the worker bees. The sting and associated venom sac of honey bees are also modified so as to pull free of the body once lodged (autotomy), and the sting apparatus has its own musculature and ganglion which allow it to keep delivering venom once detached. The worker dies after the sting is torn from its body. Despite common belief, it is the only species of bee to die after stinging.

It is presumed that this complex apparatus, including the barbs on the sting, evolved specifically in response to predation by vertebrates, as the barbs do not usually function (and the sting apparatus does not detach) unless the sting is embedded in fleshy tissue. While the sting can also penetrate the flexible exoskeletal joints in appendages of other insects (and is used in fights between queens), in the case of Apis cerana defense against other insects such as predatory wasps is usually performed by surrounding the intruder with a mass of defending worker bees, who vibrate their muscles so vigorously that it raises the temperature of the intruder to a lethal level. It was previously thought that the heat alone was responsible for killing intruding wasps, but recent experiments have demonstrated that it is the increased temperature in combination with increased carbon dioxide levels within the ball that produces the lethal effect. This phenomenon is also used to kill a queen perceived as intruding or defective, an action known to beekeepers as balling the queen, named for the ball of bees formed.

In the case of those honey bee species with open combs (e.g., A. dorsata), would-be predators are given a warning signal that takes the form of a 'Mexican wave' which spreads as a ripple across a layer of bees densely packed on the surface of the comb when a threat is perceived, and consists of bees momentarily arching their bodies and flicking their wings.