High-speed footage shows detached honeybee stinger pumps venom with double-piston valves

Left · 1High-speed video has captured how a honeybee's roughly two-millimetre stinger keeps pumping venom after it detaches from the insect's body, a process the Guardian described as previously unknown. 1 Left · 1Researchers from Macquarie University detached the stingers and filmed them pumping venom into a clear gel that mimics human skin. 1 Left · 1According to Ars Technica, the work appears in a new paper in the Proceedings of the National Academy of Sciences (PNAS, DOI 10.1073/pnas.2603916123). 2

Left · 1Worker honey bees (Apis mellifera) leave the stinger in the target and fly away. The stinger keeps penetrating tissue and pumping venom on its own, a phenomenon known as autotomy, but the exact pumping mechanism had never been directly observed. 2 Left · 1The stinger has three interlocking elements forming the venom canal: a stylet that widens into the main pumping chamber, and two sharp-tipped lancets that slide back and forth. 2 Left · 1The team removed stingers from live worker bees with forceps just before filming, partly inserted them into blocks of artificial gel, and recorded them with stereomicroscopy and high-speed colour video, followed by frame-by-frame analysis. The structures are semi-translucent, so their movement is visible. 2

Left · 1The footage showed that valves attached to each lancet change shape as they slide. They inflate like a parachute on the downstroke, sealing the chamber and pushing venom out, deflate on the upstroke, and change shape again to slip past each other in the middle. 2 Left · 1Co-author Fiorella Ramirez-Esquivel of Macquarie University said the valves act as collapsible pistons that, by pumping in opposite directions, deliver a continuous flow of venom. She said the double-piston design lets the stinger work as a compact, autonomous unit, and the dual motion also minimizes backflow. 2 Left · 1To check the findings, the team used micro-CT scans to build a 3D-printed scaled model, which showed the same pumping kinematics as the biological stingers. 2

Left · 1Future work may examine the valves' material properties, since high elasticity and low friction appear key to replicating the motion, and whether capillary action plays a role. The authors expect eventual medical and microfluidic uses, such as artificial pumps. 2