Megachile (Eutricharaea)

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Megachile Latreille, 1802
Subgenus: Eutricharaea Thomson, 1872
Common name: none

Overview

Megachile (Eutricharaea) are highly variable in color, but many species are small with black integument and pale apical hair bands on their terga (Michener 2007; Gonzalez 2008). Female Megachile (Eutricharaea) usually have white scopa except for on the apical sterna, but can have entirely golden or black scopa in rare cases (Michener 2007; Praz 2017). Megachile (Eutricharaea) range in body length from 5–16 mm (Michener 2007).

Diagnostic characteristics

(modified from Michener 2007; Praz 2017)

  • Female hind basitarsus elongate, length more than 2.5 times its maximum width.
  • Female hind tarsal claw with basal seta modified to a short, thick process.
  • Female mandible is four-toothed with the upper tooth sometimes incised giving it the appearance of five-toothed.
  • Female mandible usually without a cutting edge in the second interspace; rarely there are species with a very small cutting edge in this space.
  • Female mandible with a complete cutting edge in the third interspace, although it can sometimes be hidden behind the margin of the mandible.
  • Female sterna with apical hair bands beneath the scopa.
  • Male front coxa with tooth or spine.
  • Male mandible three-toothed with basal projection on the lower margin.
  • Male T6 preapical carina is strong and denticulate, sometimes with a median emargination. The disc above the preapical carina is covered with often dense white hair.

May be confused with

Megachile (Eutricharaea) is likely to be confused with Megachile (Eurymella) since they are both similar in size and both have a robust mandible with an enlarged apical tooth (Gonzalez 2008). Megachile (Eutricharaea) has a longer hind basitarsus than Megachile (Eurymella) and also has thickened basal setae on the tarsal claw of the hind leg (Praz 2017).

Host associations

Megachile (Eutricharaea) are generalists that have been observed visiting Amaranthaceae, Apocynaceae, Asteraceae, Boraginaceae, Brassicaceae, Carduoideae, Chenopodiaceae, Cleomaceae, Convolvulaceae, Euphorbiaceae, Fabaceae, Hydrophyllaceae, Lamiaceae, Malvaceae, Nelumbonaceae, Plantaginaceae, Polygonaceae, Rutaceae, Tamaricaceae, Verbenaceae, and Zygophyllaceae (Westrich 1989; Raw 2007).

Nesting behavior

Megachile (Eutricharaea) nest in pre-existing cavities in soil, stems, beetle burrows, and under stones (Ferton 1914; Alqarni et al. 2014). They also occasionally dig burrows in sandy or hard soil (Westrich 1989; Mazzucco and Mazzucco 2007). Leaf discs and pieces of petals are used to construct their brood cells (Westrich 1989). Nest plugs are comprised of layers of leaf discs and mud mixed with saliva (Ferton 1914).

Diversity

Megachile (Eutricharaea) is the most diverse subgenus of Megachile, and consists of approximately 240 species, nine of which have been introduced to the U.S. and several Caribbean islands (Michener 2007; Raw 2007; Gonzalez 2008; Moure et al. 2007; Rasmussen 2012).

Known invasives

Nine species of Megachile (Eutricharaea) have been introduced to the U.S. and Caribbean: Megachile apicalis, M. chlorura, M. concinna, M. derelictula, M. diligens, M. fullawayi, M.multidens, M. rotundata, and M. timberlakei (Raw 2007).

Megachile (Eutricharaea) apicalis occurs naturally in the Palearctic and has been introduced to California (Hurd 1954; Moure et al. 2007; Rasmussen 2012).

Megachile (Eutricharaea) chlorura, M. diligens, M. fullawayi, and M. timberlakei were introduced to Hawaii from Southeast Asia (Moore et al. 2008; Ascher and Pickering 2012; Rasmussen 2012). M. timberlakei was also introduced to the Galapagos Islands (Moure et al. 2007; Rasmussen 2012).

Megachile (Eutricharaea) concinna was likely accidentally introduced to the West Indies from Africa during the slave trade (Eickwort 1970; Raw 1985). It has since spread to the U.S. and the Dominican Republic (Moure et al. 2007; Rasmussen 2012).

Megachile (Eutricharaea) derelictula was introduced to Barbados from sub-Saharan Africa (Moure et al. 2007; Rasmussen 2012).

Megachile (Eutricharaea) multidens was introduced to Jamaica from South Africa (Moure et al. 2007; Rasmussen 2012).

Megachile (Eutricharaea) rotundata, the alfalfa-leafcutter bee, was intentionally introduced from their native Palearctic range to California in the 1940-50s to increase alfalfa pollination (Hurd 1954). They are now in widespread use by alfalfa seed producers in the U.S. (Hurd 1954). They have also been introduced to Chile, Argentina, Australia, and New Zealand for the same purpose (Raw 2007; Moure et al. 2007; Rasmussen 2012).

Distribution

Megachile (Eutricharaea) range from southern Europe to southern Africa to eastern and southern Asia, Australia, and Oceania (Michener 2007). Nine species were introduced to the continental U.S., Hawaii, and several Caribbean islands, including the West Indies, the Dominican Republic, Barbados, and Jamaica (Michener 2007; Raw 2007; Moure et al. 2007; Rasmussen 2012).

Distribution
​Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

<p><em>Megachile apicalis</em> female face, photo: Chelsey Ritner</p>
Megachile apicalis female face, photo: Chelsey Ritner
<p><em>Megachile apicalis</em> female lateral habitus, photo: Chelsey Ritner</p>
Megachile apicalis female lateral habitus, photo: Chelsey Ritner
<p><em>Megachile apicalis</em> female abdomen, photo: Chelsey Ritner</p>
Megachile apicalis female abdomen, photo: Chelsey Ritner
<p><em>Megachile concinna</em> female face, photo: Colleen Meidt</p>
Megachile concinna female face, photo: Colleen Meidt
<p><em>Megachile apicalis</em> female lateral habitus, photo: Colleen Meidt</p>
Megachile apicalis female lateral habitus, photo: Colleen Meidt
<p><em>Megachile apicalis</em> female abdomen, photo: Colleen Meidt</p>
Megachile apicalis female abdomen, photo: Colleen Meidt
<p><em>Megachile rotundata</em> female lateral habitus, photo: Colleen Meidt</p>
Megachile rotundata female lateral habitus, photo: Colleen Meidt
<p><em>Megachile rotundata</em> female lateral habitus, photo: Colleen Meidt</p>
Megachile rotundata female lateral habitus, photo: Colleen Meidt
<p><em>Megachile rotundata</em> female abdomen, photo: Colleen Meidt</p>
Megachile rotundata female abdomen, photo: Colleen Meidt
<p><em>Megachile rotundata</em> male face, photo: Colleen Meidt</p>
Megachile rotundata male face, photo: Colleen Meidt
<p><em>Megachile rotundata </em>male lateral habitus, photo: Colleen Meidt</p>
Megachile rotundata male lateral habitus, photo: Colleen Meidt
<p><em>Megachile rotundata</em> male abdomen, photo: Colleen Meidt</p>
Megachile rotundata male abdomen, photo: Colleen Meidt
<p><em>Megachile apicalis</em> female face, photo: Joshua Hengel</p>
Megachile apicalis female face, photo: Joshua Hengel
<p><em>Megachile concinna</em> female mandible, photo: Joshua Hengel</p>
Megachile concinna female mandible, photo: Joshua Hengel
<p><em>Megachile apicalis</em> female sterna, photo: Joshua Hengel</p>
Megachile apicalis female sterna, photo: Joshua Hengel