In vivo and in vitro studies indicate that the sternal gland secretion of the dampwood termite Zootermopsis angusticollis has fungistatic properties. Germination rates of spores of the fungus Metarhizium anisopliae were significantly reduced from 91% (controls) to 38.5% after nymphs walked over spore-seeded agar medium, but did not differ from controls when the sternal gland and surrounding cuticle were sealed with nail polish. Germination of fungal conidia was also significantly reduced after spores were incubated with cuticular extracts of either sternal or tergal segments suggesting that cuticular exudates in general may have antifungal properties.
Extracts of sternites had greater fungistatic activity than extracts of tergites, but the difference was not statistically significant. Extracts of the sternal gland significantly reduced germination rates by up to 9%. Germination rates were also significantly reduced when spores were incubated with n-caproic acid, the principal component of the sternal gland secretion in Zootermopsis, or its vapor. Sternal gland secretions in termites may have had the original function of controlling microbes within the nest and their prominent role in communication may have evolved secondarily.
Species 1: Isoptera Termopsidae Zootermopsis angusticollis (dampwood termite)
Species 2: Deuteromycotina Hyphomycetes Metarhizium anisopliae (green muscardine fungus)
Keywords: disease resistance, biochemical protection
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