Tetramorium atratulum formerly known as Anergates atratulus is an obligate workerless parasite (inquiline) in the colonies of another ant, Tetramorium caespitum. As with many socially parasitic ants, atratulumappear to be related to its host genus and the female morphology is superficially similar. Gynes are about about 2.5mm long, blackish-brown with yellow legs.
The distribution and status of T. atratulum is, not surprisingly, closely linked to that of its host species, which is itself only locally common. T. atratulum has been recorded from the cliffs at Bolt Head and Bolberry Down in S. Devon, the heathlands of Purbeck and around Wareham and Hurn in Dorset, near Burley and Beaulieu Road Station in the New Forest and the heaths at Longmoor in Hants, Pirbright Common in Surrey and the shingle beds around Dungeness. It has also been recorded from Jersey. This parasite is possibly under-recorded. It is present in only a small proportion of host colonies, it is easily overlooked, and the Tetramorium nests are difficult to excavate. Anergates atratulus is found across the Palaearctic and, along with its host, it has become well established in the eastern United States.
Status (in Britain only):
Listed as Rare (RDB3) in Shirt (1987); revised to Insufficiently Known (RDBK) by Falk (1991).
T. atratulum requires a large stable population of its host species to survive. T. caespitum itself is a thermophilous species requiring high levels of insolation at the ground surface. The largest populations of T. caespitum are found in sun-exposed, rocky or shingle coastal sites with short, sparse maritime vegetation. Some lowland heaths also support strong populations of the host but only where the vegetation is short or sparse and there are patches of bare free-draining ground.
Males of T. atratulum are degenerate and wingless, therefore mating occurs within the host nest. The mated gynes then fly out from May to August to find new host colonies.
T. atratulum has no worker caste, the queen, brood and young sexuals are therefore totally dependent on the host Tetramorium workers for food. T. caespitum workers are predators and scavengers of animal and plant material (notably including seeds).
This is poorly understood but newly mated queens appear to either secure adoption in an old queenless colony of T. caespitum, or they lead to the host queen being killed or starved by her own workers. The parasite seems to predominate in mature T. caespitum colonies where the host workers are notably large and dark. T. atratulum does not have workers of its own and so the entire resources of the host colony are diverted to producing large numbers of new T. atratulum gynes and males. Since no new host workers are generated, T. atratulum queens must produce new generations before the colony dies out in 2-5 years. The queens therefore become massively swollen with eggs (physogastric) and are themselves rarely found in nests. The yellowish larvae (contrasting with the white Tetramorium larvae), and the winged gynes or the pale pupoidal males are more often seen.
Join Adrian Knowles, bee & wasp expert on this fascinating day. Adrian is the Suffolk county recorder for bees, wasps & ants. You will learn about the ecology & lifecycle of solitary bees & wasps, nest sites, artificial nest boxes and pollinator-friendly plants. There are some 200 species of wild bees in the UK, called solitary bees because they make individual nest cells for their larvae. Some species nest in tunnels or holes in the ground, sandy banks and crumbling mortar while others use the hollow stems of dead plants such as bramble.
First recorded on the British mainland from SE London in 2016.
Information on nesting biology (Palaearctic Osmiine Bees) here
A widespread species across southern, eastern and central Europe and north Africa, north to 60 degrees, and eastwards to central Asia (Müller, A., 2016).
Status (in Britain only):
New to Britain in 2016. Specimens were found (including females with pollen loads) at the Greenwich Peninsula Ecology Park (London) in early June 2016 (Notton, Tang & Day, 2016)
Not included in any current UK keys. However, continental works that cover the identification include Amiet et al. (2004); Banaszak and Romasenko (2001)
Found in a range of dry habitats which have an abundance of suitable nest sites: gravel pits, derelict vineyard terraces, man made habitats (eg botanic gardens) and dry warm waste places (Westrich, 1989), temperate grasslands and forests (or forest edge) (Lhomme, P. 2014).
A univoltine species. Mid June to the end of July. In favourable years the species can persist into September. The British specimens were found from mid-June to the end of July.
Strongly oligolectic on Echium species (Boraginaceae)(Müller, A., unpublished, based on 29 pollen samples from 19 different localities and on field observations). Ivanov et al (2005) state that the species is monolectic on Echium, which is clearly an error of understanding.
The species nests in existing cavities in old beetle galleries in dead wood,empty snail shells, in hollow plant stems, and in old nest burrows of various aculeates (Colletes, Megachile parietina, Anthophora, Odynerus) and in the old cocoons of Osmia mustelina. The species readily takes to artificial nest sites, such as cut bamboo stems, and wood borings and the British specimens were seen at drilled wooden nesting blocks. The thick cell partitions and the nest closure are made of earth, sand and clay cemented together with saliva. (Westrich, 1989). The nesting cell partitions and nest plug made of mud. The outer surface of the nest plug is often covered with wood fibres, sand, dust etc. (Westrich, 1989).
Watching Ancistrocerus wasps nest-making in my garden bee-hotel over recent years, I had assumed that they collected mud from damp areas (in a similar way to Osmia bicornis). Last year, I was able to follow a wasp from the bee-hotel to its "collecting point" and saw that it was collecting dry soil particles. This year I witnessed the same thing, with an Ancistrocerus wasp repeatedly returning to the same point. I was able to get a series of photographs from one visit showing her collecting individual soil granules (the soil was bone dry) and then flying off with a wet mud-ball.
With the launch of the NBN's Living Atlas and the closure of the NBN Gateway maps, currently it is not possible to display maps from NBN data. We hope this will soon be resolved and maps restored to the species accounts. Please be patient - we have around 900,000 records to upload, so the wait will be worth it!