Alternative reproductive strategies of a gregarious ground-nesting bee, Dieunomia triangulifera (Hymenoptera : Halictidae)

I studied reproductive behavior of females of the gregarious ground-nesting bee Dieunomia triangulifera (Halictidae), During peak bloom of the host pl ant, Helianthus annuus, some females consistently brought pollen to one nes t (provisioning bees), whereas others visited many nests without taking pol len to any (searching bees). Searching bees were more likely to have two or more developed oocytes and crops full of pollen. The ingested pollen proba bly provided protein for egg production. The differing behavior of provisio ning and searching bees combined with contrasting internal morphology, indi cated that these two sets of behaviors were alternative reproductive strate gies. Three possible explanations for the searching bees' behavior included : usurpation, floating, or intraspecific cleptoparasitism. Each of these is evaluated as a possible function of searching behavior. Given the evidence I conclude that intraspecific cleptoparasitism is the most likely explanat ion.