#EBSstories How bees’ nests can help develop eco-friendly materials

09-09-2021

Remarkably strong bee nests are providing scientists with clues about new and eco-friendly renewable materials that could reduce adverse environmental impact. 

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Despite the tremendous progress that has recently been made in materials science, the consideration of the environmental impact of materials production is a recurrent technological challenge. Many materials come from non-renewable resources that are gradually being depleted. This requires the discovery of additional reserves, the development of new materials having comparable properties with less environmental impact, the increasing of recycling efforts, and the development of new recycling technologies. As a result, it becomes increasingly important to consider the “from cradle to grave” lifecycle of materials relative to the overall manufacturing process. With this in mind, Julio Cesar Da Silva, a scientist at the CNRS Institut Néel, started looking for bioinspiration in nature.

He came across a bee species in the Grenoble area, called mason bees or Megachile pyrenaica, which was previously thought to be extinct. These bees had the peculiarity that they make nests “hard as a rock, like a safe house for the future generation of bees, in perfect harmony with nature”, says Da Silva.

Mason bees build their nests from dust and sand clumped together with saliva and nectar. They reinforce this mortar with small pebbles, which makes it very hard as it dries. The nest remains in place for years and it is naturally destroyed without causing pollution if no longer used. The exterior region of the nests resists bad weather and climate conditions, while the inner part resists bacteria, fungus, mould, and lichen. “All this indicates that the bees can manipulate different compositions of materials for their nests and they seem to have ‘architecture skills’ to design their interior with proper ventilation and temperature adjustment”, explains Da Silva.

“The best way to investigate these types of materials is to use high-resolution X-ray imaging at ESRF”, he adds. So together with Kudakwashe Jakata, a post-doctoral researcher on beamline BM05, they are carrying out the characterisation of the 3D microstructure of the nests in high-resolution using the technique of phase-contrast X-ray microtomography. “So far the results are very promising and we can already have clues about the impact of the nest architecture design with regards to CO2 exchange, ventilation, and thermoregulation”, explains Da Silva. The team has also carried out complementary measurements using near-field ptychographic X-ray computed tomography on the ID16A beamline to understand the microstructure of the nests at the nanometre length scale.

Along with entomologists Philippe Bullet, a scientist at the platform BioPARK, and Cyril Botte, a scientist at CNRS UGA, as well as the architect Pierre-Yves Jorcin, the ultimate goal for the team is to develop a new ecological natural cement that is non-polluting, easy to use, and recyclable. And as a side effect of this research, the scientists hope to contribute to the raise awareness around this endangered bee species.

Text by Montserrat Capellas Espuny

Video by Montserrat Capellas Espuny and Mark McGee. Credits for bees' footage: https://pro.passion-entomologie.fr