The long-tongued bees in this family usually cut portions of leaves or petals as a construction material for their nests. The leaves may be used to create partitions between brood cells, to line the outer walls of the nests, or they may be chewed to create a masonry material to plug any holes in the nest. Some tribes of this family are parasitic on other Leaf-Cutting bees. Important tribes are the following: Anthidini (Carder Bees): This small tribe includes the Anthidium spp. Many species in this tribe use leaf down from such plants as Common Mullein to create a water-resistant lining for their nests. They nest in various cavities, including tunnels of insect-boring insects, hollow stems of shrubs, abandoned nests of other bees and wasps, etc. Megachilini (Large Leaf-Cutters): This includes many Megachile spp., which are among the largest Leaf-Cutters. They tend to visit the larger flowers in the Bean and Aster families, and many other flowers as well. This tribe is important in the pollination of many prairie wildflowers. They resemble bumblebees, but are somewhat smaller. Osmiini (Small Leaf-Cutters, Mason Bees): These small bees have surprisingly long tongues and nest in pre-existing cavities. They chew leaves to create masonry material for their nests. Mason bees are most common in the spring and often visit the flowering shrubs and small trees in the Rose family (including fruit trees in orchards). Stelidini and Coelioxini (Cuckoo Bees): These tribes include Stelis and Coelioxys spp., respectively. They are brood parasites on other Leaf-Cutting bees. The species from the latter tribe are more common visitors of prairie wildflowers than the former. Trypetini (Leaf-Cutters): This includes the Heriades spp., one of which, Heriades carinatum, is known as the "Onion Bee." They are not common visitors of wildflowers.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:8029
Specimens with Barcodes:7173
Species With Barcodes:1476
|This article does not cite any references or sources. (May 2013)|
The Megachilidae are a cosmopolitan family of (mostly) solitary bees whose pollen-carrying structure (called a scopa) is restricted to the ventral surface of the abdomen (rather than mostly or exclusively on the hind legs as in other bee families).
Megachilid genera are most commonly known as mason bees and leafcutter bees, reflecting the materials from which they build their nest cells (soil or leaves, respectively); a few collect plant or animal hairs and fibers, and are called carder bees. All species feed on nectar and pollen, but a few are cleptoparasites (informally called "cuckoo bees"), feeding on pollen collected by other megachilid bees. Parasitic species do not possess scopae. Megachilid bees are among the world's most efficient pollinators because of their energetic swimming-like motion in the reproductive structures of flowers, which moves pollen, as needed for pollination. One of the reasons they are efficient pollinators is their frequency of visits to plants, but this is because they are extremely inefficient at gathering pollen; compared to all other bee families, megachilids require on average nearly 10 times as many trips to flowers to gather sufficient resources to provision a single brood cell.
North America has many native megachilid species, but alfalfa leafcutter bees (Megachile rotundata) are an imported species used for pollination. The most significant native species is Osmia lignaria (the orchard mason bee or blue orchard bee), which is sold commercially for use in orchard crop pollination, and which can be attracted to nest in wooden blocks with holes drilled in them (which are also sold commercially for this purpose).
The general lifecycle of nonparasitic Megachilidae generally is:
- Nests are typically divided into cells, each cell receives a supply of food (pollen or a pollen/nectar mix) and an egg; after finding a suitable spot (often near where she emerged), a female starts building a first cell, stocks it, and oviposits.
- Then she builds a wall that separates the completed cell from the next one.
- The larva hatches from the egg and consumes the food supply. After moulting a few times, it spins a cocoon and pupates.
- Then it emerges from the nest as an adult. Males die shortly after mating, but females survive for another few weeks, during which they build new nests.
- Nests are often (but not always) built in natural or artificial cavities. Some embed individual cells in a mass of clay or resin attached to a wall, rock surface, or plant stem.
- Nest cavities are often linear, for example in hollow plant stems, but not always (snail shells are used by some Osmia, and some species will readily use irregular cavities).
Some genera of megachilids are brood parasites, so have no ventral scopa (e.g. Stelis and Coelioxys). They often parasitize related taxa. They typically enter the nest before it is sealed and lay their eggs in a cell. After hatching, the parasite larva kills the host larva, unless the female parasite has already done so, and then consumes the provisions. Parasitic species are of equal size or smaller than their victims.
- Subfamily Fideliinae
- Subfamily Megachilinae
- Tribe Lithurgini
- Tribe Osmiini
- Heriades are mason bees with narrow abdominal bands. They resemble small Osmia, but they are oligolectic (specialized on a few subfamilies of Asteraceae) and use resin from conifers, as well as plant fibers and sand, as cell wall material.
- Tribe Anthidiini
- Stelis Panzer and related genera (stelidine bees) are cleptoparasites on other Megachilidae. They belong to the tribe Anthidiini. Subgenus Heterostelis is parasitic on Trachusa.
- Tribe Dioxyini
- Tribe Megachilini
- Incertae Sedis
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