Preliminary assessment of cavity-nesting Hymenopterans in a low-intensity agricultural landscape in Transylvania

In this study our aim was to assess several traits of cavity-nesting Hymenopteran taxa in a low-intensity agricultural landscape in Transylvania. The study took place between May and August 2018 at eight study sites in the hilly-mountainous central part of Romania, where the majority of the landscape is used for extensive farming or forestry. During the processing of the trap-nest material, we recorded several traits regarding the nests of different cavity-nesting Hymenopteran taxa and the spider prey found inside the nests of the spider-hunting representatives of these taxa. We also evaluated the relationship between the edge density and proportion of low-intensity agricultural areas surrounding the study sites and some of these traits.

The majority of nests were built by the solitary wasp genus Trypoxylon, followed by the solitary wasp taxa Dipogon and Eumeninae. Solitary bees were much less common, with Hylaeus being the most abundant genus. In the nests of Trypoxylon, we mostly f...