Do hoverflies (Diptera: Syrphidae) sound like the Hymenoptera they morphologically resemble?

It has long been recognized that many hoverfly species (Diptera: Syrphidae) mimic the morphological appearance of defended Hymenoptera, such as wasps and bees. However, it has also been repeatedly suggested that some mimetic hoverflies respond with sounds on attack that resemble the warning or startle sounds of their hymenopteran models. In this study, we set out to quantitatively compare the spectral characteristics of the sounds produced by a range of nonmimetic flies, wasps, bumblebees, honeybees, and their hoverfly mimics when they were artificially attacked. The sounds made by wasps and honeybees after simulated attacks were statistically distinguishable from their hoverfly mimics. Bumblebee models of their hoverfly mimics share some similarities in the sound they produce on attack, but they were no closer acoustically to their model than a range of other hoverfly species that morphologically resemble other models. All the mimetic hoverflies tested in this study tended to sound similar to one another, regardless of the model they resemble morphologically. Overall, we found little evidence that mimetic hoverflies sound like their hymenopteran models on attack, and we question whether acoustic mimicry has evolved in this complex. Copyright 2009, Oxford University Press.