Ecology and nesting biology of the wood-boring bee Trichothurgus laticeps (Hymenoptera: Megachilidae) in a Monte desert reserve in mid-western Argentina

Abstract

Studying bee nests can enlighten our understanding of feeding specialization and phylogenetic relationships of bees. We studied the nesting and feeding habits of Trichothurgus laticeps in the Monte desert ecosystem. Our results show that T. laticeps is attracted to pre-existing cavities in wood (trap nests), which were further excavated for nest construction; nest cells are unlined and provisioned almost exclusively with pollen of the cactus Opuntia sulphurea. The species overwinters inside a hard cocoon. Our results reinforce the hypothesis previously proposed by other authors that the unworked pollen mass and oligolecty are plesiomorphic characters in the Megachilidae, and that the wood-boring behavior for nest construction indicates convergent evolution with the Xylocopinae. We also propose that the cocoon structure might represent an evolutionary novelty for the Lithurginae.