The current status and distribution of the beetles Anthonomus conspersus, Aulacobaris lepidii and Thinobius newberyi on selected Welsh Sites of Special Scientific Interest (SSSIs) in 2018
The three species selected for this contract are all Individually Qualifying Features on their respective SSSIs, yet they had not been recorded on those SSSIs for at least twenty years. There is no evidence that Anthonomus conspersus or Aulacobaris lepidii had been looked for in the intervening period and although there was some survey effort in 2004 which could have yielded records of Thinobius newberyi, this is a difficult species to find. With habitat conditions for all three ostensibly remaining suitable there was no reason to suppose that any of their populations had become extinct. Over such a long period, however, confirmation of their continued presence is clearly desirable. The rowan weevil A. conspersus was found to be strongly established at Coed Boch y rhaeadr in Migneint-Arenig-Dduallt SSSI, with adults recorded throughout the wood and on the adjacent ffridd. Historically the area was probably managed as pasture woodland and numerous ancient rowan trees are scattered throughout the more densely wooded parts of the site, as well as the open hillside. A detailed survey of the tree resource was not possible in the time available, but a rough estimate suggests that there are more than 300 trees present. A map of the denser concentrations is provided. For at least 20 years grazing stock has been fenced out of the wood as part of an agri-environment scheme and this has led to an increase in birch scrub on the lower slopes. At present there are sufficient clearings to provide suitable conditions for A. conspersus but consideration should be given to some management to retain these open spaces in the wood. The yellow crucifer weevil A. lepidii was recorded twice on the Dee Meanders in Afon Dyfrdwy (River Dee) SSSI in the 1990s but has not been seen since. Five sites were selected for survey from aerial photographs where exposed sand and gravel was obvious on the riverbanks, as A. lepidii breeds in the roots of crucifers growing in sandy sediments. A further two sites were visited that had been identified as containing potential habitat during a previous survey. The species was not found during any of these surveys and vegetational succession had taken place at both of the recommended sites such that little or no exposed sand was seen. Hostplants of the weevil were generally scarce on the remaining sites and at four of the five trampling by livestock was noticeable, with the hostplant crucifers being heavily grazed. It is probable that A. lepidii still occurs along this stretch of river but the disturbance to the shingle bars is a concern and consideration should be given to fencing some of them to give protection to the shingle invertebrate fauna. The shingle rove beetle T. newberyi is a feature of Gro Ty'n yr Helyg SSSI on the Ystwyth and Rheidol Shingles & Backwaters SSSI on the Rheidol. At the original site on the Afon Ystwyth, Gro Ty’n-yr-helyg, the river has altered course to remove most of the former bar. Suitable sediment is deposited further downstream, but this is much smaller in extent than previously. On the Afon Rheidol, the original site of records in the 1990s is no longer suitable as dense willow carr has become established over the whole area. Efforts to reach other shingle bars in the floodplain were frustrated by deep water or dense scrub and the only bar investigated, at Abercwmdolau, had a high silt load in the sediment, whereas clean sand or fine gravel are thought to be required by the species. Hand-searching and excavation on both rivers failed to discover any examples of the target species, but this is a very difficult species to find and its absence from this survey should not be taken as evidence of extinction. The current state of the Rheidol is worrying but future flood events may rework sediments to create new bars. On the Ystywth, potential sites up and downstream from Ty’n-yr-helyg should be investigated to assess their potential for shingle invertebrates.
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Dull adnabod
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- Statws a dosbarthiad cyfredol y chwilod Anthonomus conspersus, Aulacobaris lepidii a Thinobius newberyi ar Safleoedd o Ddiddordeb Gwyddonol Arbennig (SoDdGA) dethol yng Nghymru yn 2018
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Survey techniques for the three beetle species involved visual searches, hand-searches and substrate excavations.
- Dyddiad cyfeirnod y set ddata (Cyhoeddiad)
- 2018-11-12
Ystod amser
- Dyddiad cychwyn
- 2018-05-22
- Dyddiad gorffen
- 2018-08-04
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Rhychwant
Rhychwant
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- Wales (WLS)
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Dosbarthiad
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Database
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Database: records held in Welsh Invertebrate Database (WID). Documents: pdf of the report in the DMS report archive.
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Ansawdd
Ansawdd Data
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Survey techniques for the three beetle species involved visual searches, hand-searches and substrate excavations.
Allweddeiriau
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Dyfyniad
- Dyddiad (Cyhoeddiad)
- 2008-06-01
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System Cyfeirio Gofodol
Cynnwys
Gwybodaeth Cynnwys
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The current status and distribution of the beetles Anthonomus conspersus, Aulacobaris lepidii and Thinobius newberyi on selected Welsh SSSIs in 2018
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© CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose. Attribution statement: Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved.
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- 2024-05-31T09:38:32.608Z
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