Advanced imaging showed the beetle's gland system uses a rubbery material called resilin to transport its many defensive compounds. Photo by Adam Rork / Penn State
Feb. 26 (UPI) -- Ground beetles spray chemical weapons at their enemies. To protect themselves from their own toxins, carabid beetles rely on a unique compound -- a compound new research suggests could have biomedical and bioengineering applications.
Most beetles in the Carabidae family feature an abdominal gland system that produces formic acid, phenolics and concentrated hydrogen peroxide. The gland system comprises three main components: toxin-producing lobes, a reservoir chamber and a long collecting duct connecting the two. Another small duct on the tip of the abdomen caps the opposite end of the reservoir chamber in most carabid species.
"We had no idea what these tissues were made of," Tanya Renner, an assistant professor of entomology at Pennsylvania State University, said in a news release.
To find out, Renner and her colleagues used a sophisticated imaging technique, autofluorescence-based laser scanning microscopy, to study the makeup of the gland system.
The images showed the beetles use an elastomeric protein resilin to transport a variety of defensive chemicals.
"They produce more than 250 different compounds to protect themselves," Renner said.
In other insects, the rubbery resilin material connects active anatomical components -- like flea leg joints or locust wing-hinges. Until now, scientists didn't know resilin formed gland tissues.
Adam Rork, doctoral student in entomology at Penn State, collected the beetle specimens from the university's agricultural research fields. Ground beetles are a beneficial insect for farmers. Their diet includes many pest species.
"While much work has been done to describe the morphology of these glands in many subfamilies, there has been little work done on their tissue composition," Rork said. "Our findings are crucial to understanding not only how these structures evolved, but also how they withstand the stress of containing and ejecting cytotoxic chemicals."
Renner, Rork and their research partners published their analysis of the gland system found ground beetles in the journal Anthropod Structure and Development.
The researchers estimate the resilin material's unique properties could prove useful in the fields of biomedicine and bioengineering. Naturally occurring elastic compounds, like those produced by spiders, have proven stronger and more resilient than synthetic equivalents.
"They persist and are often better than synthetics," Renner said. "Since it is impermeable, highly resistant to chemicals and flexible, resilin appears to be a strong candidate for a barrier material in applications where we need to keep two different chemicals away from each other but within the same environment."
And because resilin is similar to elastin, a rubber protein found in human, the material could be used to build new tissue for humans with degenerative diseases or injuries.