A recent study published in the Proceedings of the National Academy of Sciences details how honey bee stingers continue to pump venom after the bee has flown away. The research highlights a unique double-piston pump-like mechanism that allows the stinger to deliver venom autonomously.
Honey bees (Apis mellifera) are known for leaving their stingers embedded in skin, which then continue to inject venom. The study's authors aimed to observe the venom-pumping kinematics of honey bee stingers to understand the biomechanics involved. They collected live worker bees and removed the stingers just before filming. The stingers were partially inserted into artificial gel blocks, and the pumping action was captured using high-speed videography and stereomicroscopy.
The analysis revealed that the valves attached to each lancet within the venom pumping chamber change shape during the pumping cycle. They inflate on the downstroke to create a seal and apply pressure to expel venom, then deflate on the upstroke. Co-author Fiorella Ramirez-Esquivel from Macquarie University stated, "The unique geometry of the valves is the key; they act as collapsible pistons and—by pumping in opposite directions—they’re able to deliver a continuous flow of venom."
The research team also created a 3D-printed model to mimic the observed pumping behavior, which confirmed the initial findings. Future studies may investigate the material properties of the valves and the potential role of capillary action in venom delivery. The authors suggest that their findings could inform the design of medical devices and microfluidic applications.