Hymenoptera: their diversity, and their impact on the diversity of other organisms; intraspecific biodiversity in Hymenoptera: implications for conservation and biological control; threats to the diversity of solitary bees in a neotropical dry forest in Central America; effects of increasing land utilization on species representation and diversity of aculeate wasps and bees in the semi-arid areas of southern Africa; comparison of the arboreal ant mosaic in Ghana, Brazil, Papua New Guinea and Australia - its structure and influence on arthropod diversity; bees, pollination systems, and plant diversity; diversity of native bees and agro-ecosystems; parasitic Hymenoptera, biological control and biodiversity; parasitoid webs; refuges, host population dynamics and the genesis of parasitoid diversity; the role and enhancement of parasitic Hymenoptera biodiversity in agro-ecosystems; spatial patterns in the description and richness of the Hymenoptera; what does tropical society want from the taxonomist? measuring biodiversity for choosing conservation areas; Costa Rica: an example for the study of tropical biodiversity.
