Honey bees are known to leave their stingers embedded in tender flesh once they sting you and fly away. Scientists have now determined that the stinger is able to continue pumping venom into its unfortunate victim even after the bee flies away, thanks to a unique double-piston pump-like mechanism, according to a new paper published in the Proceedings of the National Academy of Sciences. Different species have evolved different mechanisms for delivering venom, which involves piercing the skin and then pumping venom from a gland or reservoir.
Spiders, for instance, have muscles surrounding their venom glands, which contract and eject venom through hollow fangs. Bees, wasps, and ants deliver venom via their stingers, either by contracting muscles around the venom reservoir or through stiff elements called lancets working together to pump venom. Honey bees (Apis mellifera) add a unique feature: Worker bees fly away after inserting their stingers in the target, leaving the stinger behind.
The stinger continues to penetrate the tissue and pump venom on its own, a rare phenomenon known as autotomy. A honey bee’s stinger has three main interlocking elements that form the venom canal: a stylet that widens to form the main pumping chamber and two sharp-tipped lancets that slide back and forth, piercing the tissue and pumping venom into the target. But the precise mechanism by which the pumping action is achieved has never been directly observed.
The authors of this latest paper sought to capture the venom-pumping kinematics of honey bee stingers in order to identify the underlying biomechanics. They collected live worker bees and removed the stingers with forceps just prior to filming. Then they partially inserted those stingers into blocks of artificial gel and captured the pumping action using stereomicroscopy and high-speed color videography.
This was followed by a frame-by-frame analysis to better track the movement, which is visible because the structures are semi-translucent.
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