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Abstract

The family of the robberflies comprises more than 7,000 species, which are distributed all over the world and diversify on around 500 different genera. Even with a first “high quality” robberfly draft genome published in 2017, the phylogeny of this family is still not solved on a satisfying level. Nevertheless, the asilids are one of the most prominent family of flies within the brachycera. As an exception to other groups the larvae and the adults of both sexes are obligate predators. Reports of robberflies preying on huge arthropods are known since the 19th century and first studies showed the presence of venom in this taxon as early as 1850. In general venoms can be seen as key adaptions to ensure evolutionary fitness and survival of a species; often they are complex mixture of proteins, salts and different organic molecules. Single toxins often evolved from proteins with an ancestral physiological function, which were sub- or neofunctionalized during the evolution and now act as a toxin. It is known that robberflies use there needle-like hypo-pharynx to pierce through the cuticle of a prey to inject the potential venom. Besides that, morphological studies showed the presence of two gland systems, called thoracic- and labial gland system, associated with the mouthparts of these flies. The bigger thoracic gland system seems to be present in all robberfly species, while the smaller labial glands seem to vary in form and size and also lack completely in some species. A toxic effect of the toracic gland tissue could already be shown without being able to name compounds of a potential robber fly venom. The presented study combined transcriptomic and proteomic approaches to provide a first insight into the venom composition of the robberfly species Machimus arthtriticus and Eutolmus rufibarbis. Additionally, three-dimensional reconstructed synchrotron based micro computer tomography of the asilids gland systems gives an insight in to the morphological diversity of these systems within the family.