ORIGINALLY POSTED JUNE 5TH 2014
I’m in the second year of fieldwork for a PhD project looking at novel sampling methods for landscape ecology. One of the methods we’re assessing involves hand searching for beetles and bugs on flowering umbellifers such as cow parsley and hogweed. The idea is that linear patches of flowers alongside publicly accessible roads, tracks and rights of way will act as ready-made sampling platforms – natural insect ‘traps’, if you like – that can replace expensive equipment like malaise traps and sample from vegetation in a less intrusive way than, for example, a heavy sweep net, which would destroy the flowers. But most importantly of all, it’s given me a fantastic excuse to spend the spring and summer months out and about looking for insects.
On the 19th of May I was out in one of this year’s study tetrads, near Wokingham in east Berkshire. It was a fairly bright, warm day, with plenty of insects active, including a notable emergence of the varied carpet beetle Anthrenus verbasci, one of the most common beetles on my umbellifer surveys. This species usually breeds in buildings – the larvae subsist on bits of dried skin and hair in collected household dust and fluff – and then adult beetles emerge in the spring to seek out pollen sources such as umbellifers and other spring flowers before returning to the great indoors to lay eggs. As it happens, CWAC director Dr Graham Holloway runs the national recording scheme for the family Dermestidae, to which Anthrenus belongs, so I usually keep an especially close eye out for them on his behalf.
On my walk between transects two and three for the tetrad I passed a rather lovely patch of ox-eye daisies, and recalling that I’ve often found carpet beetles on this plant before – during last year’s Garden Bioblitz, for example – I stooped down to have a quick search. I immediately found three Anthrenus, and gathered them in a glass tube for inspection. All three individuals were strikingly marked, and two of them very large, half as big again as a typical individual of Anthrenus verbasci. If not a different species, these were clearly very interesting specimens, so I stowed them safely in my bag for later.
Back in the CWAC lab Graham Holloway immediately identified my beetles as belonging to the Anthrenus pimpinellae group, a complex of 18 species mostly found in southern and eastern Europe and in North Africa. One of these, Anthrenus pimpinellae, is near cosmopolitan in distribution, having been introduced to a number of countries (including the USA) presumably on imported stored product materials, as is often the case with Dermestids. This species has been recorded in Britain once before, in 1895, but as far as we can determine has not been seen since; indeed, Anthrenus pimpinellae was listed as a ‘lost species’ by Natural England in 2010.
Given all of this information, the nominate Anthrenus pimpinellae seemed the most likely candidate for the Wokingham individuals. However, upon closer study, and after consulting Marcin Kadej’s excellent treatment of this group, it quickly became clear that they were in fact Anthrenus angustefasciatus, a species not yet recorded in the British Isles. It hadn’t been described at all in 1895, and was only elevated to full species status in 2004. By complete chance, Graham had collected Anthrenus angustefasciatus in Majorca last year, and we were able to compare my new specimens with the offspring of his Majorcan beetles, which he’d placed on bird feathers and allowed to breed in captivity.
The known range of Anthrenus angustefasciatus as given by Kadej in 2007 mainly includes countries bordering the Mediterranean, so it seemed incredible that it should pop up in Berkshire without being introduced accidentally. But a quick Google search for Anthrenus pimpinellae threw up a number of images that are likely to be misidentified specimens of A.angustefasciatus in France, as well as a confirmed record from Germany. The possibility therefore exists that this insect has been undergoing natural range expansion, or more likely it has gone under the radar, misidentified in much of its range as the more widespread A.pimpinellae. When and how angustefasciatus arrived in Britain remains unknown, but it certainly seems as though southeast England is not so far outside its natural range as we might have thought. It’s possible there are more breeding populations out there awaiting discovery.
We’re currently preparing a manuscript for publication in the journal of the British Entomological and Natural History Society, outlining this discovery in the context of the general ecology and distribution of the other members of the Anthrenus genus in Britain. In the meantime, if you have records of any Dermestid species you’d like to submit to the recording scheme, Graham Holloway would be very pleased to receive them via iRecord, with attached images for verification. Alternatively, you can send specimens for identification to the address below:
Dermestidae (and Derodontidae) Recording Scheme, c/o Dr. Graham Holloway, Centre for Wildlife Assessment and Conservation, School of Biological Sciences, Harborne Building, University of Reading, Whiteknights, Reading RG6 2AS.