Plastic is piling up, and researchers are looking closely at a material most people have never heard of, bee silk.

Molecular biologist Oran Wasserman, who completed his doctorate at Utah State University in Justin Jones’ Spider Silk Lab, said silk is much more common in nature than many people think.

“Silk production is far more widespread in nature than most people realize,” Wasserman told ScienceAlert.

He said silk “has evolved independently many times, with at least 23 separate origins in insects alone,” including ants, bees and wasps.

Earlier this year, Wasserman and his team became the first to create a film from a specific type of bee silk, a step toward using the material in practical applications.

For bees, silk is used for protection.

“Social bees, such as honey bees and bumble bees, produce silk to line the brood cells of their colonies,” Wasserman said.

“Solitary bees, which make up about 75 percent of all bee species, spin silk to construct cocoons that provide protection from environmental stressors.”

Researchers have been studying different bee silks for the past 20 years, but Wasserman and the Jones lab developed what the article describes as a non-invasive way to synthesise the silk.

Wasserman’s research focused on the blue orchard bee, Osmia lignaria, a solitary bee and orchard pollinator.

Unlike silkworms, which spin a cocoon from a single continuous thread, a bee larva builds its cocoon by anchoring silk to the nest cell wall, pulling the strand across with head movements, and fastening it in a new spot until it is enclosed.

The finished cocoon has only a few structural layers, but those layers balance gas exchange, mechanical protection, moisture retention and parasite resistance.

The article says solitary bee cocoons are threatened by parasitoid wasps, which locate cocoons using chemical signals and try to punch through them to lay eggs inside the developing bee.

The cocoon is the larva’s main defence, and the material is described as puncture-proof, flexible, antimicrobial and breathable.

Wasserman’s first attempts to work with the silk involved isolating single fibres from completed cocoons, but many strands broke in the process.

“The protocol we developed isolates the silk fibers directly from the larva’s mouth,” Wasserman said.

The team uses a 3D-printed rearing system designed to mimic the bees’ natural nest cavity, then raises bee larvae inside it.

Researchers monitor each larva daily and intervene when it begins spinning, while the first threads are still loose and reachable. They then isolate the fibres and mount them for mechanical testing.

“One of the most promising aspects of the protocol is that the larvae continue to form their cocoons, indicating that the method is minimally invasive,” Wasserman said.

After isolating the strands, the team produced the silk using molecular biology techniques, inserting target genes into an engineered microorganism that produced them in the lab.

They purified the resulting proteins, called fibroins, and cast them into transparent, freestanding films.

The article says this is the first time a solitary bee silk protein has been produced this way and turned into a material.

It is not yet ready for direct use in applications, but the method allows further study of bee silk in different species.

Wasserman’s team is now combining bee silk with hagfish slime.

The article says hagfish are jawless deep-sea fish that release a viscous secretion when threatened. That secretion expands rapidly in seawater and contains mucus and fine protein threads. When those threads are stretched and dried, their mechanical properties approach those of spider silk.

Wasserman said his lab uses the same molecular workflow for both hagfish proteins and bee silk, and the materials share a similar underlying protein structure.

“Silk has been used for various purposes for millennia,” Wasserman said.

“Even so, most of that attention has gone to a handful of species, mainly the silkworm and spiders.

“Across insects more broadly, silk is strikingly diverse, spun by many species that vary in its composition and mechanical properties … But surprisingly many aspects, such as their silk and cocoons, remain understudied.

“As the field continues to progress, I expect many of those open questions will start to get answered.”

The research has been published in PLOS One and SynBio.

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