Friday, March 16th, 2007--

When given a choice, drywood termites, most of which are blind, prefer to dine on bigger blocks of wood over smaller ones. Scientists measure termite-preference by tracking tunneling in the wood block: the more the termite likes it, the more tunnels and chambers it makes in a wood block, scientists believe. Drywood termites tunnel more in larger blocks.

How can termites tell the difference between a big block and a small block, if they can't see? They use their ears, or the termite equivalent. When a termite starts snacking, it rips tiny fibers from the wood block. The rips send vibrations through the structure, which then bounce back to the termite.

A study published in the Journal of the Royal Society Interface this week shows, for the first, time that termites can sense differences in the vibrations and use those differences to determine the mass and composition of a food source. Ra Inta, lead author on the study and a research associate at the University of New South Wales at the Austrialian Defence Force Academy says: “It’s pretty amazing—these quite pathetic little creatures can actually tell a size difference between two pieces of wood.”

Termites hear with their whole bodies, especially their legs: “There are three organs associated with detecting vibration in termites,” Inta explains. “But probably the most sensitive one is the subgenual organ, which is located basically on their elbows.”

How do researchers know that the termites are using these vibrations to determine what wood to eat? In a previous study, the researchers staged a sound swap, making a small block sound like a bigger block. First, Inta and his colleagues recorded termites eating from a big block of wood. He then presented the termites with two smaller blocks of wood, except that one of the small blocks was hooked up to a speaker which was playing the big block vibration he had previously recorded. The termites always preferred the block with the bigger block sound.

To understand how the bugs can use noise to determine size, the researchers tried to trick the termites. Inta cut a wood block in half and glued back together, for instance. He tacked different materials—like aluminum and rubber—onto the block. But, the termites were tough to fool: they always were drawn to the bigger structure, regardless of the manipulations.

It’s still unclear exactly what characteristics of the vibration the termites are attuned to--frequency, speed, attenuation--but if Inta can figure it out, there may be ways to design wood so that it is less appetizing to termites. Inta says: “Part of the idea is that if we can fool them, then we know how to manipulate their behavior and then we could make something that would stop them from eating your house.” 

What did you think of the story? Send us some feedback.

--Flora Lichtman

Sources

Ra Inta
School Of Aerospace, Civil And Mechanical Engineering University Of New South Wales Australian Defence Force Academy

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