The Brazilian Atlantic Forest is on the list of the 35 world hotspots with priority for conservation because it is home to one of the most diversified and threatened fauna and flora in the world. We studied the diversity and the food webs of cavity-nesting bees and wasps and their natural enemies (parasitoids and kleptoparasites) in three Atlantic forest fragments and adjacent matrices. Although the species composition in the forest fragments was different from the adjacent matrices, the alpha diversity stayed constant. Since the structure of the interaction networks between these species has not been altered with habitat simplification, we conclude that these relations are not shaped by recent environmental changes, but by phylogenetic relations established at a more remote time.

The male of Xystromutilla bucki Suárez, 1960 is described and associated with the female based on couples reared from trap-nests occupied by Auplopus subaurarius Dreisbach, 1963 (Hymenoptera: Pompilidae). Information on the diapause of X. bucki and Pseudomethoca nr. chontalensis (Cameron, 1895) (Hymenoptera: Mutillidae) is presented. Seasonal and annual variation in the abundance of X. turrialba Casal, 1969 are also given.