Oligolecty

We have, thus, a case where different types of bees are similarly adapted to oligolecty on a certain group of plants.

The most likely explanation for oligolecty in bees is not different from the explanation of specificity of any organism to its habitat; in fact, oligolecty is a form of host specificity.

In so far as now known, all of the species exhibit a high degree of oligolecty (or monolecty) being restricted in pollen collecting to a single genus of plants.

An individual of a polylectic species that takes pollen from only a few kinds of plants is showing flower constancy rather than oligolecty.

Once oligolecty was documented, the following two summers were used for field study of widely separated populations of I. pandurata.

That oligolecty exists is indisputable, but its application to particular bee species engenders confusion and debate. […] We propose a definition of oligolecty that is sufficiently inclusive without diluting the intended meaning for undisputed cases: we define oligolecty as consistent and predictable reliance of a species on a few plant genera for their pollen needs.

In most studies sampling is limited to a few sites, and therefore oligolecty is dubiously assigned. Moreover, both abundant and minor pollen types are generally considered at a same level of importance.

The two most basal bee families, Dasypodaidae and Mellitidae, are predominantly composed of pollen specialists, indicating that oligolecty might be the ancestral state in bees[…]. In the western Palaearctic anthidiine bees, several transitions from oligolecty to polylecty were found, but none from polylecty to oligolecty[…].