Australian researchers are investigating silk from bees, ants and other insects in their search for novel light and strong fibres.
For centuries silk worms, the pupae of the moth Bombyx mori, have been venerated as the only source of silk for use in textiles.
Less well appreciated is the silk that spiders produce to create their webs – lightweight but tough nets to catch and bind their prey.
Now Australian entomologists are looking at the silk production of other insects, such as bumblebees and various ants, and comparing their fibres to the silk already identified from the European honeybee (Apis mellifera).
New Biomaterials from Insect Silk
Dr Tara Sutherland is the leader for the Biomaterials team at CSIRO Entomology.
She and her team are studying the evolution of silk in insects and other invertebrates, looking towards developing new biomaterials from naturally occurring structural proteins from these insects.
Results of their recent research were published in the November 2007 issue of Molecular Biology and Evolution, in the paper Conservation of Essential Design Features in Coiled Coil Silks.
In background information from CSIRO, Dr Sutherland explained that the silk produced by ants and bees is structurally very different from large protein sheet structures of moth and spider silk.
“The cocoon and nest silks we looked at consist of coiled coils - a protein structural arrangement where multiple helices wind around each other. This structure produces a light weight, very tough silk,” she said.
Comparing Silk Genes of Ants and Bees
Previous research had already identified the silk genes in the European honeybee, and Sutherland’s team identified and sequenced the silk genes of bumblebees (Apoidea g.), and bulldog ants and weaver ants (Vespoidea g.), and compared these to honeybee silk genes.
This enabled them to identify “the essential design elements for the assembly and function of coiled coil silk,” she said.
“To do this, we identified and compared the coiled coil proteins from cocoon and nest silks from species which span the evolutionary tree of the social Hymenoptera (bees, ants and wasps).”
Insects Use their Silk in Different Ways
Although the high quality silks of bees and different types of ants are produced by their larvae using the same sort of glands, they are used for different purposes.
Dr Sutherland said honeybee larvae produce silk to reinforce the wax cells in which they pupate, bumblebee larvae spin cocoons within wax hives (these cocoons are reused to store pollen and honey), bulldog ant larvae spin solitary cocoons for protection during pupation, and weaver ants use their larvae as ‘tools’ to fasten fresh plant leaves together to form large communal nests.
Coiled Silk the Key to Insects’ Success
Coiled coil silks appear to have evolved about 155 million years ago in aculeate insects (those with stings), other than parasitic wasps, she said. These groups of insects have evolved silks that are very tough and stable in comparison to the silkworm’s classical sheet silks, and Dr Sutherland hypothesised that the evolution of this remarkable material has underpinned the success of the social Hymenoptera.
