Abstract

The emission of distress stridulation is a common defense mechanism among insects, including species from the order Hymenoptera (ants, bees and wasps). Wasps from the family Mutillidae (also known as velvet ants) emit audible distress stridulations when attacked. While species-specific variation in the acoustic properties of velvet ants stridulation has been described, one common theme across species is the absence of ultrasonic frequency components (> 20 kHz). We recorded and analyzed the distress stridulation emitted by females of three species of Chilean endemic velvet ants, popularly known as panda ants: Euspinolia chilensis (Spinola, 1851), E. militaris (Mickel, 1938) and Reedomutilla gayi (Spinola, 1851). In general, the stridulation emitted by R. gayi is similar to the distress signal of other velvet ant species described to date. In contrast, the distress signals of both Euspinolia species differ from previously reported Mutillidae stridulations, including the presence of high-frequency spectral components, reaching the ultrasonic range. Due to the scarce information on the natural predators of South American velvet ant species, the defensive significance of distress stridulation having ultrasonic components remains unknown, however, its potential role against reptile and rodent predators is discussed and its potential role as intra-specific communication is suggested.