Silkworms have long been the basis of the world's silk industry but new Australian research points to a possible future mulberry tree-free alternative.

Scientists at CSIRO Entomology have found that silk made by the common Australian green lacewing is much tougher and can be stretched up to six times further than silkworm silk.

More importantly, according to the research to be published in the Journal of Structural Biology, its unusual structure makes it potentially much easier to manufacture artificially.

The findings are part of ongoing work at the CSIRO involving the categorisation of insects that produce silk - from wasps, to ants, water beetles and even fleas.

By looking at the variations and commonalities in the silks, the researchers hope to soon find an effective and efficient method of producing artificial silk.

Smart structures

The common Australian green lacewing (Mallada signata) uses silk to create tiny stiff stalks to hold each of its eggs on. The delicate insect pushes out a liquid drop of silk dope before stretching it out to the point at which it stiffens and then placing the egg safely on top.

It was these stalks and the way they were created that attracted the researchers' attention.

They found that the lacewing silk was unrelated to the silk created by other insects and had had its own evolutionary pathway.

Unlike the plank-like structure of other silks from spiders or silkworms, lacewing silk contains two fibrous proteins structured like a concertina door, giving it extra toughness and elasticity.

The lacewing silk protein is also shorter and less repetitive. Therefore it may be more easily reproduced artificially by fermentation in bacteria, says Dr Tara Sutherland, part of the CSIRO research team.

Sutherland and her colleagues are now in the middle of experimenting with ways of doing that.

"Silks are made under benign conditions. They're made at room temperature, from an aqueous system and from readily replaced building blocks, so it's a very environmentally friendly process, in contrast to the synthetic equivalents," she says.

Applications

There is almost as much excitement about silk in the world's entomology laboratories as on the fashion catwalk.

"The material has a lot of strength and it's very, very light so it's quite remarkable. It's also very tough," says Sutherland.

In addition to traditional textile uses, the biocompatibility of the natural fibre means that it is being increasingly used in high-tech medical applications such as providing the scaffolding for growing new human cells on.

Silk produced by silkworms is limited in its use, as scientists haven't been able to control the form of the material except with a complicated dissolving and reforming process.

"That's quite a difficult process to do," says Sutherland. "And there's some concern that when you try to remake it into the form that you want, you're not mimicking all the properties in the natural material."

The ultimate goal is to artificially create insect silk, complete with its strong, beautiful and environmentally friendly natural properties, says Sutherland.

The common Australia green lacewing could be the one to provide the best way forward.