Scientists studying honey bee stingers have identified how the barbed weapons continue injecting venom after the bee detaches and flies away. A research team used high-speed videography and 3D-printed models to reveal the biomechanics behind this autonomous venom delivery.
The study, published in the Proceedings of the National Academy of Sciences, focused on the stinger's internal architecture. Honey bee stingers contain three main interlocking parts that form a venom canal: a central stylet that widens into a pumping chamber, and two lancets with sharp tips that slide back and forth. Attached to each lancet are valves that control venom flow.
By partially inserting removed stingers into artificial gel blocks and recording with stereomicroscopy and high-speed color videography, researchers tracked the valves' movement frame by frame. The analysis revealed a double-piston mechanism. During the downstroke, the valves inflate like parachutes, creating a seal that applies downward pressure to expel venom. On the upstroke, the valves deflate. When the valves meet in the middle, they change shape to pass each other without blocking the channel. This opposing motion delivers continuous venom flow while minimizing backflow.
Fiorella Ramirez-Esquivel of Macquarie University, a co-author, explained: "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." She added that "the double piston design adds complexity, but it's the key to the stinger being able to deliver venom continuously in a compact, autonomous unit."
The team verified findings using micro-CT scans to build a 3D-printed scaled prototype that mimicked the pumping behavior. Frame-by-frame analysis of the artificial model showed the same kinematics as biological stingers. Future work may examine the material properties of the valves, particularly their elasticity and low friction, and investigate whether capillary action aids venom transport. Prior research has adapted bee stinger structures for microneedles and drilling devices. The authors anticipate their work will inform medical applications and microfluidic pump design.