If a honey bee stings a person, its stinger usually breaks off in the person's body and the bee usually dies within a few minutes. The ancestors of bees were parasitic wasps, and they needed an ovipositor (their egg-laying organ) that could pierce the hard outer exoskeleton of an insect in order to lay their eggs inside its body, using it as a host for the developing eggs. Stingers and their associated poison glands evolved to protect the colony against invading insects, especially bees from different hives. Interestingly, most wasp and bee stingers are straight, like a sewing needle, but the stinger of a honey bee is barbed.
The barbed stinger can penetrate another insect's exoskeleton and retract safely, leaving the bee intact and able to sting again; but it breaks off in soft flesh, so a honey bee worker can only sting a person once, whereas other types of bees and wasps can sting people multiple times. Queen honey bees can sting, but they very rarely use their stinger for defense, probably because it could risk damaging their ovipositor, which is central to their role in the colony.
Meliponid or stingless bees have vestigial or atrophied stingers and are not capable of stinging. Although most species of stingless bees are generally mild-mannered, a few species will defend themselves by biting fiercely when they are threatened, and Dylan Voeller and James Nieh have filmed Trigona spinipes and Melipona rufiventris fighting viciously over food. David Roubik, Brian Smith, and R. G. Carlson described at least two species within the Oxytrigona genus that secrete caustic salivary substances made up of formic acids and other defensive chemicals, making their bite extremely uncomfortable. The stingless bee Trigona fulviventris marks potential predators with a chemical secretion that elicits additional bees to react defensively by buzzing, biting, and hair pulling.
Another species enters the eyes, ears, and nose of the threatening animal or person and then buzzes its wings loudly; this strategy is an effective way to make a predator run away from the bee nest. Other species will attack a potential nest intruder with sticky nest substances, like resins or honey. Being covered in gooey materials discourages further nest intrusions. Alexandros Papachristoforou studied Cyprian honey bees Apis mellifera cypria that have an interesting way of defending themselves against the local Oriental hornets Vespa orientalis. Hornets, like all insects, breathe through spiracles, which are holes in their exoskeleton. They contract their abdominal muscles to exhale and relax the muscles to inhale, and these muscle movements open and close plates in the exoskeleton that protect the holes. The researchers found that bees cluster around the hornet to defend against it, and they actually suffocate the hornet by making it impossible for it to open its spiracles to take in air. This form of asphyxiation has not been documented as a defense against other invaders, but it is a strategy that could work against many other insects.
Japanese honey bees, Apis cerana japonica, guard against their local, predatory hornets, Vespa simillima xanthoptera, in a different way. Both the bees and the hornets are accustomed to a relatively cool climate, and Masato Ono and colleagues found that when bees are threatened by a hornet, a huge group of bees thermoballs it, surrounding the predatory hornet in a cluster and vibrating their muscles until they heat the hornet to a temperature that kills it (113 degrees Fahrenheit, 45 degrees Celsius). This form of thermal strategy seems to be a rare type of colony defense, and it is not commonly seen against other intruders.
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Note: This article was sent to us by: Bernard C. Monoud at 08192010
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