Use of reed stem nest boxes by solitary bees and wasps near Göttingen, Lower Saxony, Germany

Published source details

Steffan-Dewenter I. (2002) Landscape context affects trap-nesting bees, wasps, and their natural enemies. Ecological Entomology, 27, 631-637

Background

The diversity of wild bees is declining in Europe and lack of forage resources and nest sites in intensive agricultural areas are suspected causes. This study monitored the uptake of reed stem nest boxes at sites with different landscape characteristics in intensively farmed land near Göttingen, Lower Saxony, Germany.

Action

Nest boxes consisted of 150-180 internodal stem sections of common reed Phragmites australis, with diameters of 2-10 mm, cut 20 cm long and put in 10.5 cm diameter plastic tubes. Reed-filled tubes were attached to wooden posts 1 – 1.2 m above the ground, with four nest boxes to a post.

Two posts (eight nest boxes) were placed at 15 different sites (120 nest boxes altogether) from April to October 1997. The proportion of different habitats in the surrounding landscape of each site was measured using field surveys (750 m radius) and digital maps (3 km radius).

In October, occupied reeds were cut open and the number of brood cells in each stem counted. Occupants were reared in the laboratory and identified to species where possible.

Consequences

Eleven bee species, seven digger wasp species (Sphecidae) and six eumenid wasp species (Eumenidae) used the nest boxes, making 1,640 brood cells in total. The most abundant and widespread occupants were the red mason bee Osmia rufa, the common yellow face bee Hylaeus communis, and the wasps Trypoxylon figulus, T. medium and Symmorphus gracilis.

Nine species of natural enemy (seven wasps, one fly Diptera, one beetle Coleoptera) were found. These attacked on average 14.8% of brood cells. 13.7% of bee brood cells, 23.7% of eumenid wasp brood cells and 15.4% of digger wasp brood cells were attacked.

The number of species in the nest boxes (but not the number of brood cells) was correlated with the proportion of semi-natural habitat in the landscape, a pattern brought about by changes in the number of wasp (not bee) species.

Note: If using or referring to this published study, please read and quote the original paper, the abstract of which can be viewed at: www3.interscience.wiley.com/journal/122361883/grouphome/home.html.