Nesting biology and foraging ecology of the wood-boring bee Lithurgus chrysurus (Hymenoptera: Megachilidae)

The biology of the wood-boring bee Lithurgus chrysurus Fonscolombe, 1834 is described and the biology of the genus Lithurgus is summarized. Lithurgus chrysurus is univoltine and over-winter as prepupae inside cocoons. The females excavate their own burrows in various dead woods and they do not reuse burrows. The cells are separated by partitions composed of cut wood pieces. To assess the diet breadth of L. chrysurus, pollen analyses were conducted on 8 samples of provisions from 3 nests and 2 feces samples from one nest. The provisions averaged 30,600 pollen grains per mg of dry matter. The proportion of broken pollen grains averaged 3.3% and was consistent among nests and for provisions and feces. Centaurea (Asteraceae, tribe Cynareae) was the dominant pollen type found in all provisions and feces, accounting for 98.0 to 99.9% of the pollen based on the number of grains. This proportion was similar among nests for both provisions and feces. These results indicate that, at the study site, L. chrysurus was strictly oligolectic on Centaurea pollen while nectar was probably collected on other plant species as well.