This bee-fly is a parasitoid of some of the larger solitary bees (probably in the genus Andrena), which are active in the spring, although the exact hosts have yet to be determined. Large colonies of the host bees have specific nesting sites, usually involving bare ground into which they burrow. The bee-fly requires flowers for nectar, although the plant species concerned are not known. It is almost certain that the bee-fly can only thrive where large congregations of nesting bees of certain species are established. A metapopulation structure, involving several such colonies, may be required in order to allow for fluctuations in abundance of the host bees at any particular colony.
The dotted bee-fly underwent a major decline and retraction in range at the time that many species of solitary bees crashed during the 1960s-1970s. This coincided with intensification of agriculture and other land use, though the climatic conditions in the early 1960s may have contributed towards the trend. Though recorded from most southern counties, including inland populations in Cambridgeshire, Warwickshire and Worcestershire, for the most part only certain coastal sites in southern England and South Wales have maintained viable populations of this species. In 1996-97 the dotted bee-fly appeared in good numbers in a few inland districts (mainly south Gloucestershire and a site in Warwickshire), apparently in response to the resurgence in numbers of various species of solitary bees following a sequence of hot summers. The species has a wide range in Europe.
In Great Britain this species is classified as Nationally Scarce.
Current factors causing loss or decline
The decline of host bee populations, caused by the loss of nesting sites and reduction of suitable flowers, as a result of intensification of agriculture.
Some of the known populations are on SSSIs and NNRs.
Action plan objectives and targets
Maintain populations at all known sites.
Enhance population size at the more viable sites.
Ensure that there are 20 strong populations, representative of the historic geographic range by 2010.
Proposed actions with lead agencies
Policy and legislation
Where appropriate, include the requirements of the dotted bee-fly when preparing or revising prescriptions for agri-environment schemes. (ACTION: CCW, NE, MAFF, WOAD)
Site safeguard and management
Where possible, ensure that all occupied habitat is appropriately managed by 2005, for example through SSSI or agri-environment scheme management agreements. (ACTION: CCW, NE, MAFF, WOAD)
Ensure that the habitat requirements of the dotted bee-fly are taken into account in any relevant development policies, plans and proposals. (ACTION: CCW, NE, LAs)
Ensure that the dotted bee-fly is listed in site management documents for all relevant SSSIs. (ACTION: CCW, NE)
Consider notifying sites supporting viable populations of the dotted bee-fly as SSSIs, where this is necessary to secure their long-term protection and appropriate management. (ACTION: CCW, NE)
Species management and protection
Consider reintroducing populations to sites where this species has become extinct, if this is necessary to maintain 20 viable populations across the geographic range. (ACTION: CCW, NE)
Advise landowners and managers of the presence of the species and the importance of beneficial management for its conservation. (ACTION: CCW, NE, MAFF, WOAD)
As far as possible, ensure that all relevant agri-environment project officers, and members of regional agri-environment consultation groups, are advised of locations of this species, its importance, and the management needed for its conservation. (ACTION: CCW, NE, MAFF, WOAD)
Future Research and Monitoring
Undertake surveys to determine the status of this species. (ACTION: CCW, NE)
Conduct targeted autecological research to inform habitat management by 2005. (ACTION: CCW, NE)
Establish a regular monitoring programme for the dotted bee-fly and its hosts at key sites. (ACTION: CCW, NE)
Pass information gathered during survey and monitoring of this species to a central database so that it can be incorporated in national databases. (ACTION: CCW, NE)
Communications and Publicity
Promote opportunities for the appreciation of the dotted bee-fly and the conservation issues associated with its habitat. (ACTION: CCW, NE)
Links with other action plans
Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume IV: Invertebrates (March 1999, Tranche 2, Vol IV, p149)
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