Osirini

Genus Guides

Epeoloides(Macropis Cuckoo Bee)

Osirini is a tribe of cleptoparasitic bees in the Apidae. Most are exclusively Neotropical and parasitize nests of bees in the tribe Tapinotaspidini. The genus Epeoloides is exceptional, containing one North American and one European that parasitize the melittid genus Macropis. All species possess a unique morphological trait: a tiny embedded in the beneath the , possibly functioning as protection against stings during nest invasion.

Osirini by (c) Evgenii Iaitskii, some rights reserved (CC BY), uploaded by Evgenii Iaitskii. Used under a CC-BY license.

Epeoloides by (c) anonymous, some rights reserved (CC BY). Used under a CC-BY license.

Epeoloides pilosulus by (c) Matt Pelikan, some rights reserved (CC BY), uploaded by Matt Pelikan. Used under a CC-BY license.

Pronunciation

How to pronounce Osirini: //oʊˈsaɪˌraɪnaɪ//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Presence of a small embedded in the beneath the distinguishes Osirini from all other bees. This structure is unique to the tribe and may be visible with magnification. Cleptoparasitic lifestyle and associated morphological reductions (reduced pollen-carrying structures) may aid identification, though these features are shared with other parasitic lineages.

Images

Distribution

Predominantly Neotropical. Most restricted to the Neotropics. Genus Epeoloides exceptional: one in North America, one in Europe.

Host Associations

Tapinotaspidini - Primary tribe for most Osirini
Macropis - for Epeoloides only; Macropis is in Melittidae, not Apidae
Monoeca haemorrhoidalis - Documented for Protosiris gigas
Diadasina sp. - Documented for Leiopodus trochantericus

Life Cycle

Cleptoparasitic development. First instars of some exhibit abbreviated or quiescent stages. In Epeoloides coecutiens, the first instar has an unusually short stadium, and the second instar kills the . In Leiopodus trochantericus, the first instar remains quiescent for an extended period before killing the host at the late second or third instar stage.

Behavior

Nest invasion and cleptoparasitism. Females enter nests to lay . Larvae kill host offspring to secure resources. Killing occurs at different developmental stages depending on : second instar in Epeoloides coecutiens, first instar (after prolonged ) in Leiopodus trochantericus.

Ecological Role

of solitary bees. regulators of .

Similar Taxa

ProtepeoliniAnother tribe of cleptoparasitic Apidae; some historically confused or closely related. Both tribes contain with reduced scopae and similar body plans.
EpeoliniTribe of cleptoparasitic Apidae with similar cleptoparasitic lifestyle and morphological convergence; distinguished by the unique cervical of Osirini.
Tapinotaspidini tribe frequently mistaken for due to close ecological association; Osirini can be distinguished by the cervical and cleptoparasitic .

More Details

Unique Cervical Sclerite

The tiny embedded in the beneath the is a unique autapomorphy of Osirini among all bees. Its hypothesized function is protection against stings from bees during nest invasion, though this remains a functional hypothesis rather than experimentally confirmed.

Biogeographic Exception

The Epeoloides represents a significant biogeographic outlier within Osirini, with Holarctic distribution (North America and Europe) contrasting with the otherwise exclusively Neotropical range of the tribe. This genus also exhibits a shift to the Melittidae, whereas other Osirini parasitize Apidae.