New research has revealed how a detached honey bee stinger keeps pumping venom, a natural design that could inspire miniature medical devices.
A honey bee stinger can continue pumping venom and penetrating tissue even after detaching from the bee, according to new UNSW Canberra research that could inspire future micro-pumps, microneedles and drug-delivery devices.
The study, published in Proceedings of the National Academy of Sciences, provides the first detailed observations of the mechanics behind the honey bee stinger’s venom-pumping action.
Using high-speed videography, micro-CT imaging and a physical model, the researchers found that the stinger operates using two flexible pumping elements that move in opposite directions.
Together, they form a double-piston pump that allows venom to be delivered continuously while the stinger moves deeper into tissue.
The design could eventually help engineers develop compact systems capable of delivering small amounts of fluid precisely at a particular location, including in medical devices and drug-delivery technologies.
Dr Sridhar Ravi, research project lead at UNSW Canberra, said the research had revealed an intricate mechanism operating inside the detached stinger.
“The stinger works like a small piston pump, but the unique feature is that it has two deformable pistons working together,” Dr Ravi said.
The two pistons operate in opposite phases, while one moves downwards to push venom through the stinger, the other collapses as it moves upwards, allowing the pumping chamber to refill.
This enables the stinger to continue delivering venom without drawing it back into the chamber, a problem that can occur in a single-piston system.
“Imagine a syringe with a single piston. When the plunger moves forward, it pushes fluid out, but when it is pulled back, it can create suction and draw fluid back in,” Dr Ravi said.
“The bee stinger avoids this problem by using two deformable pistons. While one piston pushes venom forward, the other collapses and allows the chamber to refill.”
The pistons are connected to the lancets, the sharp structures that penetrate the skin, meaning the same mechanism helps the stinger pump venom and move deeper into tissue.
The bee stinger is particularly interesting from an engineering perspective because it combines the functions of a piston and a valve in the same flexible structure.
“The stinger is remarkable because it performs a complex function at a very small size scale. It can deliver a small amount of fluid precisely while also penetrating a material and continuing to operate after becoming detached,” Dr Ravi said.
“What is particularly interesting is that the bee stinger combines the functions of a piston and a valve in the same deformable structure. In many engineered systems, these are separate components, but the stinger performs both functions using one integrated design.”
After a worker honey bee stings, the bee flies away but leaves its stinger lodged in the target. The detached stinger contains muscles, nerves, the venom sac and the pumping structures needed to continue functioning independently.
The researchers found that strong, regular pumping continued for between 15 and 70 seconds, while the stinger continued twitching for several minutes, and smaller movements could continue for up to 10 to 15 minutes after the initial sting.
“The honey bee stinger is much more than a sharp needle. It is a tiny, self-contained machine that combines a venom pump with a micro-penetrating mechanism,” Dr Ravi said.
The researchers from UNSW Canberra and Macquarie University used micro-CT imaging to create a detailed three-dimensional reconstruction of the stinger, including the pumping chamber and venom canal, and high-speed video allowed them to observe the two valves moving, deforming and passing one another during the pumping cycle.
“The pistons are flexible enough to collapse and squeeze past each other, but they are also strong enough to generate pressure and pump venom,” Dr Ravi explained.
“The pistons repeatedly deform, pass one another and then recover their shape without breaking or losing their function.”
The research builds on earlier work by the team, which used high-resolution three-dimensional imaging to map the anatomy of the honey bee.
This latest study takes this research further by observing the stinger in action and revealing how its internal structures work together to pump venom and penetrate tissue.
The findings improve scientists’ understanding of how honey bees deliver venom and could also provide insights into related structures found in other insects, including ants, wasps and other bees.
The study also raises new questions about how the stinger’s materials allow it to deform repeatedly without failing, and how the biological design could be reproduced in engineered systems.
“The main message is that piston pumps can operate at an extraordinarily small size,” Dr Ravi said.
“The honey bee stinger provides a possible pathway for designing new types of miniature pumps, but we still need to understand how to reproduce the design and where it could be applied.”