Why termites don’t bite off more than they can chew
With their ability to chew a house right out from under its occupants and build some of the largest and most complex nests of the animal kingdom, termites have long been known as crafty.
Now UNSW researchers have uncovered some sophisticated talents that allow key pest species, Coptotermes acinaciformis, to feed and flourish.
Dr Sebastian Oberst and Professor Joseph Lai from UNSW Canberra, and University of Western Australia Associate Professor Theo Evans have shown for the first time that Coptotermes, the ‘tree-piping’ termite, is able to distinguish load-bearing from non-load bearing wood.
The wood-eating insects will preferentially gnaw through areas that don’t support weight before moving onto load-bearing timbers, which they buttress with supporting walls made from clay to ensure it doesn’t collapse as they feast.
“The ability to determine the weight-bearing in wood explains some of the patterns of termite attack in houses,” said Oberst.
“They usually eat the wood that is not load-bearing first, such as door and window frames, floorboards behind cupboards and so forth, and attack the strong load-bearing timbers such as joists and bearers later.”
The clay walls are built progressively so if the termites are disturbed and forced to abandon the wood they haven’t expended more energy than is strictly necessary.
It allows termites to access wood that would otherwise be off-limits, offering 700 times more energy than they expend in erecting the scaffold.
It is thought to represent an evolutionary leap from foraging to nest building.
The ability to detect load bearing is likely to have evolved in response to the scarcity of readily accessible wood for Coptotermes, a ground-dwelling mainland Australian species that builds mound-nests and eats eucalypts.
“The problem for ground-living termites is most wood is not available to eat because it is in tree-trunks that support the huge weight of the tree,” Oberst said.
“Eating the wood at ground level would cause the tree to collapse, and so crush and kill the termites.”
Once a load is detected, the termite switches from feeding mode to transporting clay, and continues to periodically sample the wood until enough clay has been added to disperse the load before continuing to eat, according to the researchers.
Though not proven, loadbearing is thought to be detected through acoustic or vibration sense rather than physical or chemical methods.
The research, published in Scientific Reports (an online, open access journal from the publishers of Nature), was supported by the Australian Research Council’s Discovery Project Grant Scheme and is available at www.nature.com/articles/srep20990 (link activated from 10 am 8 February 2016 UK time).
Media contact: Natalia Komarova, UNSW Canberra (02) 6268 8760 / 0468 989 181, publicrelations@adfa.edu.au
