Cellophane Bees May Hold the Key to Plastics That Break Down Naturally in Soil
Scientists may have found a promising biological model for producing plastics that retain the flexibility of conventional materials but break down naturally in soil within months, potentially offering a new approach to tackling the growing global plastic pollution problem.
The discovery comes from a study of the cellophane bee (Colletes inaequalis), which produces a natural polyester-and-silk material to line its underground nests. Researchers found that the bee-produced material rapidly deteriorates in soil despite having molecular properties resembling those of some durable synthetic plastics.
The study, published in the Proceedings of the National Academy of Sciences (PNAS), suggests that understanding how this natural material degrades could help scientists design a new generation of more environmentally sustainable plastics.
Unlike conventional plastics, which can persist in landfills and natural environments for decades or even centuries, the cellophane bee’s nest lining showed substantial deterioration within a relatively short period.
To investigate its properties, researchers subjected freshly constructed nest linings to chemical tests, heating measurements, microscopy and X-ray scattering. They also examined samples after four, seven and 11 months of exposure to natural soil conditions.
The results showed that the polyester content declined from 73% to 40% of the nest’s weight within just four months.
After seven months, the material had developed visible cracks. By the 11th month, it had become brittle and prone to crumbling.
Despite its ability to break down, the material initially demonstrated considerable flexibility, retaining its shape when folded or crumpled.
This combination of durability during use and relatively rapid deterioration afterward makes it a potentially valuable model for developing biodegradable alternatives to single-use plastics.
The cellophane bee’s unusual material has attracted scientific interest since researchers first identified the species’ underground nest linings nearly five decades ago.
The bees produce the substance in a specialized gland called the Dufour’s gland, which is connected to their stinger. They use the flexible, translucent material to line their underground nesting chambers.
Scientists had previously observed that the material did not appear to accumulate at nesting sites, even though successive generations of bees returned to the same locations and constructed new nests year after year.
In their study, the researchers noted that some nesting aggregations contain more than 10,000 individual nests, with successive generations continuing to add new material to the soil over decades.
Yet the polyester does not appear to accumulate in these locations.
The researchers are still investigating the biological and chemical mechanisms responsible for the material’s rapid deterioration.
Their analysis found that approximately 60% of the freshly produced polyester had a crystalline structure, a characteristic generally associated with greater resistance to degradation.
However, the researchers suspect that the crystals may be poorly organized, potentially exposing chemical bonds to water and enzymes that facilitate decomposition.
They also detected enzymes in fresh and four-month-old nest linings capable of breaking ester bonds in a test substance, suggesting another possible explanation for the material’s rapid breakdown.
Further research is needed to establish exactly how these processes work and whether they can be replicated in commercially manufactured plastics.
The researchers said the discovery could provide valuable insights into designing materials that combine the useful characteristics of conventional plastics with improved environmental degradability.
“These results establish Colletes polyester as a valuable resource in the push for a more sustainable plastic economy, and future work should investigate the source of this material’s remarkable degradability to inform design of next-generation, truly sustainable PE-like polyesters,” the study authors wrote.
The discovery offers scientists a natural material to study in the search for alternatives to conventional plastics. It could eventually help advance the development of plastics designed to serve their intended purpose and then break down more readily after disposal, reducing their long-term burden on the environment.
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