Stenusine, an antimicrobial agent in the rove beetle genus Stenus (Coleoptera, Staphylinidae)
Stenusine is well known as the alkaloid, discharged by the rove beetle, genus Stenus Latreille (Coleoptera, Staphylinidae). The Stenus beetles employ the alkaloid as an escape mechanism when on water surfaces. In the case of danger, they lower their abdomen and emit stenusine from their pygidial glands. Stenusine shows a low surface tension and therefore a high spreading pressure; these properties propel the beetle quickly over the water. Many Steninae do not live in habitats with open waters, but in detritus, leaf litter, mosses, etc. This raises the possibility that stenusine might also have another function, e.g., as antibiotic or fungicide. Stenus beetles show an intense grooming behaviour. With gas chromatography–mass spectrometry analyses we could prove that they cover themselves with their secretion. To tests its antimicrobial properties we conducted agar diffusion tests with stenusine and norstenusine, another substance that is abundant in most Stenus species. Both compounds have an antimicrobial effect on entomopathogenic bacteria and fungi. Stenusine not only allows for an extraordinary method of locomotion on water surfaces, it also protects the Steninae from being infested with microorganisms.
KeywordsStenus Stenusine and norstenusine Antibiotic and fungicidal
We thank Dr. T. Gedig for providing us with authentic stenusine and norstenusine, and we gratefully acknowledge the DFG for the funding of the project. We would also like to thank Lars Körner for the exchange of experience on Stenus beetles and Christine Loiselle for correcting the English of the manuscript. I hereby declare that all experiments comply with the current laws of Germany.
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