Proportions of aposematic colouration in bees and wasps (Hymenoptera, Aculeata) and their main mimics – hoverflies, clearwing moths and longhorn beetles

Although bees and wasps are well known as aposematically coloured insects, the role of their aposematic patterns has not been studied to the same extent as other animal and insect groups, i.e., butterflies or beetles. We focused on the fauna of Central Europe, a region with a high diversity of bees and wasps, with more than 1200 species recorded. For each species, we recorded whether aposematic colouration was present as well as which of the main four colouration combinations was present, for both males and females. The same was studied for the three main groups of mimics: clearwing moths, hoverflies, and longhorn beetles. We found that more than 73% of bees and wasps were aposematically coloured, with the black-yellow combination being the most common, recorded in more than half of all aposematically coloured species. The proportions of the main colour combinations varied among the studied groups of bees and wasps. All Chrysididae were metallic. Pompilidae were dominantly black-red, while most Mutillidae exhibited a black-red-white colouration. Parasitic species were more often aposematic (more than 95%) than nesting predators and nesting herbivores were. Regarding the mimics, clearwing moths were nearly all aposematic, and they used Batesian mimicry as their main defence against predators. In contrast, only approximately half of the longhorn beetles were aposematic, whereas the rest of the species used crypsis. All groups of mimics were most commonly coloured black-yellow, but several species in all three groups also possessed the other three colour combinations. Aposematic coloration, along with both Batesian and Müllerian mimicry, functions as a warning signal to vertebrate predators but can also deter insect predators and parasites. However, these interactions remain understudied and deserve further investigation.