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18th September 2017

The Rose Bedeguar Project

by Robin Williams

Introduction

An introduction given to the Royal Entomological Society/BPGS meeting in London in 2006.

In 1999 I suggested to the British Plant Gall Society (BPGS) that more attention should be paid to the organisms which formed the galls, and their parasites. Prior to that the main attention of the society had been on finding and identifying the galls themselves, culminating in the eventual publication, in 2002 (Field Study Council), of a set of thoroughly tested keys to British galls. At the AGM it was decided to form an Invertebrate group, which I was asked to lead.

The first meeting of the new group was held at Leicester in March 2000 and an immediate decision was taken to undertake a series of long-term studies of readily found galls and their inhabitants. The first of these is into the inhabitants of the Rose bedeguar gall, Diplolepis rosae (Linnaeus 1758), in Britain, and is still under way at this date. It is planned that this will continue until a reasonable coverage of the country has been obtained. An all-day workshop, and progress meeting, is held every year in early spring which attracts a lively and participative audience. Workshops have covered ‘Gall-midges’, led by Keith Harris; ‘Inhabitants of oak-galls’, led by myself; and many aspects of the bedeguar.

The study

The bedeguar was chosen because there was no single volume available which covered biology, keys to insects and descriptions, as well as the fact that the gall was reasonably plentiful, readily recognised and easy to rear out. This latter factor was important for an amateur-led organisation. Hard galls, like the bedeguar, are easy to keep in pots, with little risk of mould provided they are collected when already hardened off.

Three distinct courses of action were instituted immediately:

Preparing keys proved relatively easy, though they have been modified many times since the first set appeared, as new species have been found or details revised for others. We are told they are easy to use and provide a reliable means of identification. Once these had been produced there were two courses of action for those who joined in the project; to rear and identify the insects themselves; or to send them in to Simon Randolph for identification. All identified insects have had their data entered into the MapMate database and, to date, some 1300 entries have been made, though these cover many thousands of insects, as a single entry may be for many insects of a single species.

The use of ratios in aiding identification has been proved in the study of oak-gall insects, so as many specimens as possible have been measured and then ratios calculated. Measurements include lengths of body, excluding ovipositor sheaths; head+thorax; forewing; flagellum for chalcids, or antenna for ichneumons & cynipids; ovipositor sheaths. The % ratios produced are Head+Thorax/body; Flagellum/Head+Thorax; Wing/Body; Ovipositor sheaths/Body and these are quoted where the insect keys out, together with a short description of the insect, the number that have been measured and size ranges. Drawings are used, at the point of recognition, to illustrate every use of technical terms or to show the structure to which the point refers. In this way the use of a glossary has been avoided.

The list of insects has grown during the course of the project and may well continue in this way if studies on oak galls are to taken as a model. At present, seventeen insects are included in the keys including the causer, an inquiline and parasitoids. Two of these are doubtful, but possible; one from a study of its arrival in other rose galls and one which may not be an original inhabitant. One, Aulogymnus skianeuros (Ratzeburg 1848), reared from two locations in England, is new to this gall, and has only once been found on Continental Europe, while two other parasitoids, Mesopolobus fasciiventris Westwood 1833, and Torymus microstigma (Walker 1833), found in other galls in Britain, have been newly-reared from the bedeguar.

Detailed descriptions are being made of each species, to a set plan, illustrated with black-and-white pictures of specimens taken through a video camera on a microscope. These are designed to show the shape, as confirmation that the identification seems correct, rather than provide final identification. Colour pictures are also being taken of live specimens as they emerge.

Desk-research

Originally it was planned that a single comprehensive volume of findings would be produced at the end of the project but, after trawling all possible sources, a considerable and comprehensive amount of information was assembled and it was decided to go ahead with this desk-research as a separate volume. Last year, the BPGS published ‘The Natural History of the Rose Bedeguar Gall and its Insect Community’, by Simon Randolph – 92 pages, bringing together known information on the communities within the gall. This covers the classification, adult morphology and distribution of D. rosae; host plant species, physiological condition of the host plant and its development; the bedeguar plant community; information on parasitoids and frequencies of D. rosae communities across Europe.

RES involvement

The final volume will give keys, full descriptions, information on rearing and location, and any extra facts obtained since publication of the first volume. There will also be a summary of the current position and suggestions for any further work which may be indicated. Currently, we do not have a complete coverage of the country, though more of our members are collecting galls this year. However, we are not confining the project to BPGS members. Anyone can to join in with collection and/or identification and we would be particularly pleased if RES members would participate. Any support you can give would be welcomed.

Keys

The latest set of keys is always available from Kyntons Mead, Heath House, Wedmore, Somerset BS28 4UQ, and we will provide as much help as is needed. This is an important and comprehensive project which will bring together current knowledge and past research into two easily available, clearly-written volumes.

Appreciation

I must specially thank Dr R.R. Askew, and Professor Joe Shorthouse, for their help in sorting out problem areas and offering us their wide knowledge. I would also like to single out Mrs Maggie Frankum, from among the many others who have helped, for her untiring efforts in collecting, and persuading others to do the same.

References

Simon Randolph, The Natural History of the Rose Bedeguar and its Insect Community. British Plant Gall Society 2005 – see the publications page.

Margaret Redfern, Peter Shirley, Michael Bloxham, British Plant Galls; Identification of galls on plants & fungi. Field Studies Council 10. (2002) 207-531.

Rearing and Recognising Inhabitants. Robin Williams. Progress on the Rose Bedeguar Project. Cecidology Vol. 20, No 2; Autumn 2005, 57-8

Keys to adult insects which may emerge from Bedeguar galls (2Mb MS Word doc) Robin Williams.

The Bedeguar Project – Some Practical Tips. Cecidology 18, No 1, Spring 2003, 2-6