Carabid beetles produce caustic chemicals that they spray to defend themselves against predators, and the compound that protects their bodies from these toxic substances shows promise for use in bioengineering or biomedical applications, according to new research. The family Carabidae represents an extremely diverse line of insects, with almost 40,000 species. One of the traits that allows them to thrive is a unique gland system. It manufactures, stores and propels toxic chemicals -- such as formic acid, phenolics and concentrated hydrogen peroxide -- to ward off insect, amphibian and even small mammalian predators that want to eat the beetles. The researchers found that the tissues in the glandular system transporting the defensive chemicals were rich in soft, rubbery resilin, a compound found in many insects and other arthropods. Resilin provides elasticity to mechanically active tissues, such as flea leg joints or locust wing-hinges. There is currently interest among scientists in the compounds that insects and spiders produce because these structures have evolved and proven they are strong enough to hold up in the real world. Shown here: the Pygidial gland secretory lobes of a Pennsylvania ground beetle, greatly enlarged through the confocal laser scanning microscopy. The glandular spheres (yellow) are where defensive chemicals are synthesized, which are subsequently transported to a reservoir chamber via a resilin-rich collecting duct (blue).
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