The current total number of species of hymenoptera recorded in the British Isles is around 6600. As with all such figures it is a moveable feast. New species are constantly being added to the list and lumping and splitting of species changes the total. For example, the bumble bees Bombus terrestris and B. leucorum are thought to be variants of the same species and recently a similar situation has arisen in respect of B. ruderatus and B. hortorum. Table 1 shows the approximate totals for various groups in Britain and the numbers of recorded species in the Worcestershire BRC. The total of 251 species comes from 1671 individual records. It is immediately obvious that the majority of species nationally belong to the Parasitica whilst the bulk of BRC records are for the Aculeata. This is because the Parasitica are particularly difficult to identify, belonging as they do to families of Chalcids, Braconids, Ichneumonidae, etc. within which many individual species are almost identical, whilst the aculeata contain the more familiar wasp-waisted social and solitary bees, wasps and ants. It will be seen that 20 out of 26 recorded species of Parasitica in the BRC are of gall-forming Cynipidae which can be identified by the plant galls they produce.
|Order||Sub-order||Family||No. Records in BRC.|
|Hymenoptera (6600)||Symphyta (470)||Sawflies||Cimbicidae||2|
The total of 201 aculeate species from a national total of about 570 looks a good proportion. However, it hides a site based bias. For several years Dr. M.E. Archer, a nationally recognised authority on hymenoptera, has been visiting the Worcestershire heathlands at Devilís Spittelful and Rifle Range and Hartlebury Common and by 1998 he had recorded 116* species which makes the sites of regional importance. The list includes several rare, nationally notable species. If these records were to be removed from the Worcestershire list it will be seen that coverage for the rest of the county is relatively meagre. It will be important to monitor how the heathland populations respond to site management.
My present concern is to address the problem of under recording in the wider county and here we have one invaluable source of information. In the mid to late 19th century J.E. Fletcher established a national reputation as an entomologist and made a collection of hymenoptera and diptera plus a few other groups. This is the collection on which Harry Green and I have been working and it will clearly provide an important baseline from which changes can be identified. These records are not yet in the BRC but as our work in restoring and cataloguing the collection, which unfortunately is in very poor condition, is completed we must ensure that they are added to the database. My contribution to date has been to complete the work on two boxes which have been found to contain at least 66 species of hymenoptera collected from 22 sites and there are several more boxes to go. I have included a list of the aculeate species and sites as appendices. There is still some uncertainty as to the identity of some specimens which do not seem to relate to labels in the box and also some names used by Fletcher do not seem to appear in the current R.E.S. checklist of hymenoptera.
During 1999 I began my own survey of the hymenoptera and the first impression gained is of a significantly lower diversity than was found by Fletcher, which accords with other national data. I accept that since this was my year one, my lack of experience and the very limited number of sites visited almost certainly resulted in serious under recording. Furthermore, the identification of the solitary bees is not helped by the lack of keys and I have many specimens awaiting definite identification. A key by Mr. George Else of the Natural History Museum is eagerly awaited but the last information was that it is probably still two years away. In the meantime a scattered literature going back to the late 19th century has to be used.
The importance of the of the hymenoptera lies in their use as indicator species. Michael Archer (1996) states:
Solitary bees and wasps can be readily surveyed in the adult stage without environmental damage. Their abundance and distribution is very sensitive to countryside change, particularly the decline of traditional countryside. These characteristics make this group particularly suitable for site assessment for wildlife conservation.
His paper goes on to discuss why the solitary species are under such threat and how an index of diversity for a site has been developed.
I hope to continue recording in the coming years and to try the diversity index calculation. However, it is clearly beyond the scope of one person to achieve a great deal in less than a few decades! I would be grateful, therefore, to receive any hymenoptera records and doubly thankful for any specimens which you can spare. I am intending to restrict my activities to the aculeates and will not be getting involved with parasitica or symphyta. I will try to let you know the identity of any specimens you can send but the answers may be a long time coming as I have a long way to go before I will feel really comfortable with identifying beyond genus level to species level.
*Further analysis of the records has revealed 158 species of aculeates for the combined Hartlebury Common, Devilís Spittleful and Rifle Range.
Crown East Wood, Powick, Worcester (his home in St. Johnís), Bransford, Old Hills, Henwick, Cotheridge, Martley Road Nr. Worcester, Pole Elm, Middleyard Coppice, Oldbury Farm (Worcester), Hallow, Eastbury, Grimley, Whitehall (pub.?), Little Oldbury, Boughton, Monk Wood, Tibberton, Sinton Green, Spetchley, Crown Park Wood.
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