Megachile Reflexa

The genus ''Megachile'' is a cosmopolitan group of solitary bees, often called leafcutter bees or leafcutting bees; it also includes the resin bees and mortar bees. While other genera within the family Megachilidae may chew leaves or petals into fragments to build their nests, certain species within ''Megachile'' neatly cut pieces of leaves or petals, hence their common name. This is one of the largest genera of bees, with more than 1500 species in over 50 subgenera. The alfalfa leafcutter bee (''Megachile rotundata'') is managed on a commercial scale for crop pollination, and has been introduced by humans to various regions around the world.

Ecology

Nests are sometimes constructed within hollow twigs or other similarly constricted natural cavities, but often are in burrows in the ground. Nests are typically composed of single long columns of cells, the cells being sequentially constructed from the deepest portion of the tunnel outwards. The female places an egg in each cell with a supply of food, generally pollen, sometimes mixed with nectar. She builds a cap and walls off the cell. The larva hatches from the egg and consumes the food supply. After moulting a few times, it spins a cocoon and pupates, often after several months of hibernation as a prepupa. It emerges from the nest as an adult. Males, which are typically smaller and emerge in advance of females, die shortly after mating, but females survive for another few weeks, during which time they build new nests. Numerous families of wasps and bees parasitize ''Megachile'' nests, including Gasteruptiidae, Leucospidae, Sapygidae, and various kleptoparasitic megachilids, such as the closely related genus ''Coelioxys''. '' M. rotundata'' and '' M. campanulae'' are among of the first insects documented in scientific literature to use synthetic materials for making nests.

Many ''Megachile'' species use cut leaves to line the cells of their nests. It is thought that the leaf discs help prevent the desiccation of the larva's food supply. Various species in the genus, especially those in the subgenus ''Chalicodoma'' and related groups, do not use cut leaves to line the cells, but instead use fairly dry plant resin, which they carry in their mandibles. The subgenus ''Chalicodoma'' includes the world's largest bee, ''Megachile pluto'', as well as one of the largest megachilids in the United States, the recently introduced Asian species, ''Megachile sculpturalis''.

Some ''Megachile'' species have no lobe (arolia) between their claws, thus are unable to climb smooth walls or glass.Baker, Donald B.; Engel, Michael S. A new subgenus of Megachile from Borneo with arolia (Hymenoptera, Megachilidae). American Museum novitates; no. 3505
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Leafcutter bee by Bernhard plank.jpg, ''Megachile centuncularis'' cutting a leaf
Megachile-pjt.jpg, ''Megachile sp.'' with cut leaf
Leafcutting 1 6431.JPG, Leaves cut by ''Megachile'' sp.
Leaf_cutter_bee_nest.jpg, Dissected nest of a ''Megachile'' bee
Leaf_cutter_bee_nests.jpg, Nests of ''Megachile'' bees from Bangalore, India.
Cut_leaf_bits_from_a_Leaf-cutter_Bee.jpg, Dissected cut leaf bits from a nest.

Diversity

The genus ''Megachile'' contains 56 subgenera with 1520 recognized species. See also the list of ''Megachile'' species.

Notable subgenera:
* ''Callomegachile''
* ''Chalicodoma''
* ''Chelostomoides''

Notable species:
* ''Megachile albisecta'' (Klug, 1817)
* ''Megachile campanulae'', bellflower resin bee
* ''Megachile fidelis'', faithful leafcutting bee
* '' Megachile perihirta'', western leafcutting bee
* ''Megachile pluto'', the largest bee in the world
* ''Megachile rotundata'', alfalfa leafcutter bee
* ''Megachile rubi''
* ''Megachile sculpturalis'', giant resin bee
* ''Megachile texana'', Texas leafcutter bee

Gallery

Megachile fortis (head) from Badlands National Park, South Dakota - USGS Bee Inventory and Monitoring Laboratory.jpg, ''Megachile fortis''
Megachile ericetorum.jpg, '' Megachile ericetorum''
Megachile Subgenus Xanthosarus male.jpg, Male ''Megachile'' Subgenus ''Xanthosarus'' with modified front legs
Megachile shelter 1.jpg, Shelter built for ''Megachile''
File:LeafCutterLyd.png, Leafcutter bee life cycle
File:Leafcutter bee pupae.png, Comparison between a modern pupa and a fossil pupa from the La Brea Tar Pits
File:Megachile inimica female sunflower.jpg, ''Megachile inimica'' female
File:Megachile pugnata pugnata female.jpg, ''Megachile pugnata pugnata'' female

References

* , 2006: A New Subgenus of ''Megachile'' from Borneo with Arolia (Hymenoptera: Megachilidae). ''American Museum Novitates'' 3505 : 1–12. . Full article


* , 2006: The subgenus ''Megachile (Dasymegachile)'' Mitchell with special reference to the Argentine species (Hymenoptera: Megachilidae). ''Neotropical Entomology'' 35 (6): 791–802. Abstract and full article: .
* ; 2009: Cladistic analysis of ''Megachile'' (''Chrysosarus'') Mitchell and revalidation of ''Megachile'' (''Dactylomegachile'') Mitchell (Hymenoptera, Megachilidae)
''Zootaxa''
2284: 48–62
Abstract & excerpt
* , 2008: A new species of Megachile (Eutricharaea) from western Saudi Arabia related to Megachile walkeri (Hymenoptera: Megachilidae). ''Acta Entomologica Slovenica'' 16(2).
* ; ; , 2012: A review of ''Megachile'' (''Chelostomoda'') Michener (Megachilidae: Megachilini) known from China with the description of a new species. Zootaxa, 3267: 55–64
Preview
* , 2005: A study on the genus ''Megachile'' Latreille from China with descriptions of fourteen new species (Apoidea: Megachilidae). ''Acta Zootaxonomica Sinica'' 30 (1): 155–165.

External links

''Megachile'' Identification Guide (female)
discoverlife.org
''Megachile'' Identification Guide (male)
discoverlife.org
List of Species
discoverlife.org
Worldwide Species Map
discoverlife.org

{{Taxonbar, from=Q261844

Bee genera