Can the Bumps on a Beetle Wing Solve our Water Problems?

Newswise — Climate change, pollution, and a multitude of threats are putting our freshwater supplies at risk. Water collection and purification technologies are becoming increasingly important, especially in major urban areas. In places such as the San Francisco Bay area, access to freshwater is limited. There, fog collection technologies have piqued the interest of many engineers looking to mediate the shortage of freshwater. For further inspiration, some researchers have begun exploring how animals harvest fog for a source of freshwater. Dr. Hunter King, who classifies himself as more of a physicist than a biologist, is studying Namib desert beetles for clues about how these otherwise water-starved creatures collect water from fog. This remarkable survival feature lies in the tiny bumps on the beetle’s wings. King describes his finding at the annual meeting for the Society for Integrative and Comparative Biology meeting being held in Tampa this week.

The unique water harvesting attributes of this beetle’s wings was first described about ten years ago. This technology even inspired a “self-filling” water bottle. Challenges persist if we hope to capitalize on this technology to solve human problems on a larger scale. This is where King steps in. The early work of Kings’ colleagues focused on the “wettability” of the wing bumps–the surface’s ability to collect water from fog. However, King was inspired to approach the problem from a different angle. He addressed whether surface texture could also play a role in water harvesting efficiency.

Despite his inspiration arising from desert beetles, King has never experimented with the beetles themselves. He remarked, “As far as I’m concerned, it’s all physics. It’s just the biological context has got so much richness and interesting things to look at.” Instead of beetles, King is armed with a tunnel where he can manipulate fog and air flow. In this tunnel he places spherical targets that are either smooth or rough. The rough targets were modified to resemble the bumps found on the wings of the Namib desert beetles. With the use of his wind fog chamber King compared how effective each target was at capturing water. His preliminary findings are that rough targets are more efficient at collecting fog because they intercept the water molecules and subsequently contain them between the bumps. Evidently, whether the surface is water-fearing or water-loving, fluid dynamics may play an important role in water collecting efficiency. “Just putting a little obstruction will get you a long way in terms of actually catching fog.” Changing the surface chemistry of water collecting technologies can be pricey, though adding modified “bumps” is relatively cheap and easily increase efficiency.

King’s findings do not stop at his fog tunnel. A surprising realization is that some desert beetle species who have bumpy wings may be better suited for collecting fog, but actually do not do so. The behavior of these species remains a mystery to biologists. Perhaps these other species hold further clues to developing tools that can solve human challenges.

The integration of biology and physics allows King to understand both the mechanisms and functions behind behaviors in organisms. There are many lessons we can learn from studying the behaviors of organisms that have succumbed to millions of years of evolution. Evolution has worked out many kinks behind fog collection behavior in these beetles, and engineers may benefit from learning from Mother Nature’s tricks.