| Andrena | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Andrenidae |
| Subfamily: | Andreninae |
| Genus: | Andrena Fabricius, 1775 |
| Type species | |
| Apis helvola | |
| Subgenera & species | |
See text | |
Andrena is a genus ofbees in the familyAndrenidae. With over 1,500 species, it is one of the largest genera of animals.[2] It is a stronglymonophyletic group that is difficult to split into more manageable divisions;[3][4] currently,Andrena is organized into 104 subgenera.[2] It is nearly worldwide in distribution, with the notable exceptions ofOceania andSouth America. Bees in this genus are commonly known as mining bees due to their ground-nesting lifestyle.
Andrena are generally medium-sized bees; body length ranges between 8 and 17 mm with males being smaller and more slender than females. Most are black with white to tan hair, and their wings have either two or three submarginal cells[clarification needed]. They carry pollen mainly on femoralscopal hairs, but manyAndrena have an additional propodealcorbicula for carrying some pollen on their thorax.[5] They can be distinguished from other bees by the broad velvety areas in between thecompound eyes and theantennal bases, called facial foveae. Some other genera in the family Andrenidae also have foveae though, so the best identifying feature unique toAndrena is the presence of a ring of hairs on the underside of their face called the "subgenal coronet".[3]
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AllAndrena are ground nesting, solitary bees. They seem to have a preference for sandy soils.[6] The genus includes no parasitic or social species, though some nest communally or in aggregations. After mating, each female bee digs a burrow, collects pollen to form firm, round provisions for the larvae to eat and places them in cells lined with a shiny secretion.[5] Larvae do not spin a cocoon and they overwinter as adults. They typically have one generation per year and adults are only active for a few weeks.Andrena nests are attacked by many other insects includingbrood parasitic bees,blister beetles, various parasitic flies, andStrepsiptera.[7]
ManyAndrena are host-plant specialists, in which a species visits flowers of only a single or a few closely related plants.OligolecticAndrena have specialized on many different plant groups and have morphological and behavioral adaptations that suit them for their pollen preference. For example, all members of the subgenusCallandrena specialize on pollen from the plant family Asteraceae and have highly branched, fluffy scopal hairs to hold aster pollen.[8] According to Larkinet al. 2008,oligolecty was the basal trait forAndrena and a generalist diet has evolved multiple times across the genus.[9]
Andrena are common in temperate regions of Europe, Asia, and North America and most diverse in areas with a Mediterranean climate. A small amount of species are present in sub-Saharan Africa, and there are none in South America, Australia and nearby islands, or Madagascar.[5]
Partial list of species:
See comprehensiveseparate list.
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