Forest microsite influence on captures of flying Hymenoptera by yellow pan traps

Insects in the order Hymenoptera are considered useful indicators of environmental changes, and yellow pan-traps constitute one of the most used sampling methods to collect them. Here, we analyze the influence of microsite features on the flying Hymenoptera communities obtained using yellow pan-traps, through a short time of exposure in three microsites of fragmented forest: interior (I), north (NB) and south facing (SB) borders. We compared values of richness and abundance of total Hymenoptera, as well as parasitoids, predators and pollinators among microsites using rarefaction and extrapolation curves and Generalized Linear Mixed Models. Number of individuals obtained in NB were two-fold and 74% greater than the ones obtained in SB and in I respectively, whereas estimated total species richness was higher in the forest interior, followed by SB and ultimately by NB. Parasitoids and predators were more frequently trapped in NB. Even when data were obtained through a short period of sampling in five sampling sites, our results emphasize the need to consider the influence of the location (border vs interior) and the geographic orientation of edges in which pan-traps are placed in order to correctly assess the abundance of flying Hymenoptera in fragmented forest landscapes.