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= Exoneura bicolor = Exoneura bicolor (E. bicolor) is a native Australian allodapine bee species,

more commonly know as reed bees and is one of Australia's least known social bees. They exhibit a range of social organisation from solitary to semisocial interactions, with many nests having constant contact between pupae and adult bees. E. bicolor and other Exoneura species are regarded as an important group of native pollinators within Australia. E. bicolor is found throughout montane open forest and heathland ecosystems in the temperate zone of south-eastern and western Australia. They are also found in sandy environments adjacent to beaches. E. bicolor construct their nests in the pithy centres of dead plant material such as in tree ferns and grass trees.

Description
E. bicolor are approximately 8mm long and are two toned in colour with a glossy black head and thorax and an orange-brown coloured abdomen. Their legs are orange with small hairs covering them and they have hind wings. Body size is weakly associated with reproduction dominance with dominant females tending to be larger than the other bees within the colony. Most bee larvae resemble grubs, lacking legs and are mostly bald, however, E. bicolor larvae have fleshy lobes and unique hair patters on their bodies. E. Bicolor adults are relatively long lived as many bee species live for only a few weeks. Female E. bicolor can live up to 16 months of age and even longer.

E. bicolor feed on native plant nectar and pollen which they collect for their nests prior to laying eggs but also exploit the resources of non-native introduced crops. This resource exploitation of non-native crops is observed with most native bees with generalised foraging behaviours and are important in cropping and agricultural pollination, as well as he pollination of native flora. E. bicolor has evolved as a plant pollinator in a flammable environment in an extremely fire prone country.

Nest description
The nests created by E. bicolor do not resemble the stereotypical hexagon shaped cells seen in cartoons and of those of honey bee nests. E. bicolor nests are constructed in dead plant matter such as tree ferns, grass trees, and lantana plants, consist of unlined, unbranched burrows that are not divided into cells.

Taxonomy
Exoneura bicolor are an Australian allodapine bee species. E. bicolor belongs to the Apidae family within the order Hymenoptera, consisting of ants, wasps and bees. E. bicolor was first described in 1854. The allodapine genera are unique among non-apid bees, and are the oldest genera of allodapine bees. Bees within the Exoneura genus are more commonly referred to as "reed bees", due to the plant material they construct their nest burrows in. Exoneura represent 67 of the 197 classified Apidae species. Exoneura species are important native and non-native crop pollinators in Australia.

Nesting
The Exoneura genus contains several species which have high levels of cooperative nest use and cofounding. The unsegmented nests are occupied by more than one female, and new nests are founded by a single female up to six cofounders with majority of the new nests being excavated by a solitary female bee. They excavate the pith in the stem of the plant where they add nectar and pollen to the chamber and will lay eggs over time. Egg laying will commence only a few days (4-7) after the nest gas been founded and constructed. Egg production occurs from late winter through to early summer, with some E. bicolor populations being univoltine (only producing one brood per season). As E. bicolor nests are unbranched and not divided into single cells, larvae are reared progressively in a single communal chamber which leads to a high degree of physical and social contact between the adults and immature/juvenile bee colony members and nest occupants. As there is only a single communal chamber, there are juvenile bees at all stages of development as well as the adult bees. With pupation and eclosion occurring in the single, shared burrow chamber, pupae and adult bees are in constant physical contact with each other. As the larvae are all together without individual cells, their morphology is more complex and variable than the larvae of other genera of bees. A couple of female bees will guard the nest entrance by blocking it with their abdomen.

Most E. bicolor broods eclose, emerge as an adult individual, over a period of less than two weeks but egg laying for the next generation does not commence until some 5 to 6 months later. Female E. bicolor bees overwinter in their natal nests with some reusing it for the nest season if it is still suitable and in a usable condition. Opportunities for reproduction are staggered, with females reproducing anywhere from 6-16 months of age with all females capable of laying eggs. Multiple females are able to produce eggs within a single nest, but the dominant female can produce pheromones that keep the ovaries of subdominant females from developing with only one or two egg layers in each nest.

Social Behaviour and Colonies
E. bicolor is a social allodapine bee which exhibits a range of social organisation from solitary through to quasocial and semisocial. Social characteristics of E. bicolor include high frequencies of multifemale brood-rearing nests with no overlapping generations. There is only a difference between a day or so in eclosion time which is sufficient amount of time to establish initial hierarchies within E. bicolor. These hierarchies may be maintained for up to 7 months after emergence as adults but differences in age become relatively insignificant.

Colony sizes in montane regions tend to be larger than those in heathland regions. Heathland populations differ from montane populations in showing low levels of cofounding new nests but may have a second smaller brood. In montane areas, new nesting substrate is continuously renewed in highly localised areas, surrounding existing nesting sites, as tree ferns shed senescent fronds. As the sites are close together there is low genetic diversity among the montane populations. In the heathland regions, Xanthorrhoea scapes are renewed only after fire, but these sites are then quickly recolonised by females from outside the burnt areas. After the initial influx and increase of nesting sites post fire, nesting sites become increasingly scares until the next fire passes through the ecosystem.