The term oligolecty is used in pollination ecology to refer to bees that exhibit a narrow, specialized preference for pollen sources, typically to a single genus of flowering plants. The preference may occasionally extend to multiple genera within a single plant family, or be as narrow as a single plant species.
Such pollinators are often called oligoleges or simply specialist pollinators, and this behavior is especially common in the bee families Andrenidae and Halictidae. Attempts have been made to determine whether this narrow host preference is due to an inability of the bee larvae to digest and develop on a variety of pollen types, or a limitation of the adult bee's learning and perception (i.e., they simply do not recognize other flowers as potential food sources), and most of the available evidence suggests the latter. However, a few plants whose pollen contains toxic substances (e.g., Zigadenus) are visited by oligolectic bees, and these may fall into the former category.
There are some cases where oligoleges collect their host plant's pollen as larval food, but for various reasons rarely or never actually pollinate the flowers. A well-studied example is the relationship between the Yellow Passionflower (Passiflora lutea) and the Passionflower Bee (Anthemurgus passiflorae) fin Texas.