Further observations on Athous campyloides Newman, 1833 (Col., Elateridae) in Worcestershire
P.F. Whitehead, Moor Leys, Little Comberton, Pershore, Worcestershire WR10 3EH Email: paul@thewhiteheads.eu
Introduction
The Nationally Scarce click beetle Athous campyloides Newman is one of the more enigmatic British terrestrial elaterids and it is only relatively recently that progress has been made in understanding its autecology. Like some of its congeners adult A. campyloides are generally crepuscular with the implication that it may be under-recorded. Mendel & Clarke (1996) indicated that this is a dominantly south-eastern species in England. It was first recorded in the midlands from Worcestershire during 1993 when a dead adult was dissected from the oesophagus of a recently expired Robin (Erithacus rubecula (L., 1758)) at Little Comberton (SO94 30 m a.s.l.) (Whitehead, 1995). That site went on to reveal a breeding population which was markedly synanthropic and also hygrophilous; larvae of A. campyloides were later found in large volumes of peat-based compost in regularly watered plant containers and in a pile of old damp bonfire ashes (Whitehead, 1998).
In describing A. campyloides new to Wales, Mann (1998) cited records from woodland in or close to Cardiff and from a vegetated shingle bank at Llandaff. Two years later Alexander (2000) provided habitat data for the outlying south Cornish population backed up by reference to the British National Vegetation Classification. Such details can be especially useful when trying to unravel geographic affinities and here A. campyloides was found on cattle-grazed pasture on brown earth. Given this diversity of habitat one may enquire: why is this species apparently so diffusely scattered along its north-western British range-edge?
The autecology of Athous campyloides in the light of recent additional Worcestershire records
Until 2003 A. campyloides was known in Worcestershire only from Little Comberton settlement, then on 14 April 2003, the author found a larva 12 cms deep in clayey alluvium in the valley of the River Avon at North and Middle Littleton (SP04 20 m a.s.l.) only about 40 m from the bankside. This interesting record is the first find of larval A. campyloides in Worcestershire’s open countryside. Although sharing some of the affinities cited by Mann (1998), the habitat is quite dissimilar to that described by Alexander (2000). However he goes on to say that the Cornish site is situated in a valley where the sediments are likely to be both compacted and enriched by cattle which may possibly be to the advantage of A. campyloides.
The rather singular larval tolerances of A. campyloides were confirmed again in Little Comberton (SO94 30 m a.s.l.) on 8 August 2013 (20 years after the first record there and 350 m distant from it) when a mature larva was found 75 cms deep at the contact of a large heap of commercially-produced compost and a sheet of film plastic underlying it. From this, and from the other lines of evidence it seems likely that A. campyloides might be adapted to tolerate significant variations in subterranean air: water ratios and occasional saturation. On 7 March 1996 larvae were found from 20-66 cms deep at Little Comberton in what was mostly clay.
The final recent record of A. campyloides in Worcestershire presently known to me is of an adult male that flew to light at Little Comberton (SO94 30 m a.s.l.) at 2350 hrs on 23 June 2005 in an ambient temperature of 16oC.
As is often stated A. campyloides may well eat the roots of grasses but it is certainly a larval predator of worms (Whitehead, 1998) and doubtless other soft-bodied invertebrates; the larva from the compost bed on 8 August 2013 was in the company of some small worms of the genera Eisenia and Lumbricus. Perhaps A. campyloides selects sediments or sites where the predation of worms, known to respond rapidly to changes in water levels, is made somewhat simpler.
The European range of Athous campyloides
Athous campyloides is a demonstrably west European species found in Belgium, France and Spain and not occurring south-east of Germany although in that country it is believed to be introduced (Cate, 2007). It cannot presently be regarded as Lusitanian because it is scarcely known in Ireland. What does seem clear is that this is a species on which the last word has certainly not been written.
References
Alexander, K.N.A., 2000. The Cornish records for Athous campyloides Newman (Elateridae). The Coleopterist 9:41-42.
Cate, P.C. 2007. Elateridae pp. 89-209 In: Löbl, I. & Smetana, A. (eds), Catalogue of Palaearctic Coleoptera 4. Apollo Books.
Mann, D.J., 1998. Athous campyloides Newman, 1833 (Elateridae) in Wales, and other species of interest. The Coleopterist 7:18-19.
Mendel, H. & Clarke, R.E., 1996. Provisional atlas of the click beetles (Coleoptera:Elateroidea) of Britain and Ireland. pp. i-ix, 1-73. Ipswich Borough Council Museums.
Whitehead, P.F., 1995. Observations on the British population of Athous campyloides Newman, 1833 (Elateridae) new to the English west midlands. Entomologist’s Monthly Magazine 131:138.
Whitehead, P.F., 1998. Observations on the British population of Athous campyloides Newman, 1833 (Elateridae). The Coleopterist 7:94-95.