SUBTERRANEANBEETLES 11 SUBURBAN GARDENS IN SOUTH-WEST LONDON AS HOMES FOR SUBTERRANEAN BEETLES J. A. Owen 8KingsdownRoad,Epsom,SurreyKT173PU. IN THE SPRING of 1995, the trial of a prototype underground pitfall-trap in the author's garden revealed that it was providing a home for the subterranean weevil Raymondionymus marqueti (Aube) and a number of other soil-inhabiting beetle species (Owen, 1995). To find out more about the subterranean beetle fauna of gardens in the area, underground pitfall-traps were set in a number of suburban gardens in south-westLondon. Thesurvey The study was carried out during 1995, 1996 and 1997. Traps were set in gardens usually in a border near the perimeter fence in soil containing roots of trees or shrubs. Mostly, only one trap was set in each garden but two were set in one garden and three in another. A few traps were set in the middle of grass lawns. All the gardens lay within a circle of radius 15km from the centre of Epsom, Surrey. In preliminary studies, traps were set in a few gardens fortwo orthree weeks only but, to allow reasonable comparison between gardens, only data from gardens in which traps were for at least 12 weeks sometime in the period May to August are considered in this paper. Four ofthe gardens had been created on chalk (rendzina), one onfine sand, five onloam andtwoonclay. The pitfall-traps were set and operated as previously described (Owen, 1997a), with the minorchange ofhaving an empty plastic drinking containerpushed into the top of the mesh cylinder to make the trap more secure against the entry of surface fauna. They were charged with a mixture of equal parts malt vinegar and sweet sherry. The contents of traps were examined at intervals of two to eight weeks and all the beetles present identified and counted. Because more than one trap was set in some gardens, trapping effort at each garden was computed in terms oftrap-weeks. Thetotaltrappingeffortexpended was496 trap weeks. Results The 2240 beetles collected comprised 60 species. A list ofthese is given in Table 1, which indicates the number of gardens in which each species was found and the numbers of each species trapped. The relative abundances of species varied considerably. A few species were found in some numbers but no fewer than 20 species (33% of the total) were represented by single specimens. No species was trapped in all 12 gardens butRaymondionymus marqueti was trapped in 10 gardens and two others - Rhizophagus perforatus and Anommatus duodecimstriatus were trappedinninegardens. Four of the species trapped are Red Data Book species (Hyman and Parsons, 1992; 1994) viz Alevonota aurantiaca (RDBl), Trichonyx sulcicollis (RDB2), 1 12 ENTOMOLOGIST'SRECORD,VOL. 11 25.i.l999 Anommatus diecki (RDBKj and Langelandia anophthalma (RDB3j and three are Nationally Notable viz. - Acrotona parens, Athous campyloides and Anommatus duodecimstriatus^ The influence of soil type on the catch is summarised in Table 2. On average, gardens on chalk produced the largest catch (expressed as beetles per trap-week) whereas gardens on clay, produced on average, the largest number ofspecies. Traps setinthemiddleofgrass lawns failed tocatchany beetles. Discussion The fact that gardens can possess an extensive beetle fauna is well documented. Henderson (1945, 1946) recorded 366 species from his garden at Purley, Surrey. Allen (1998) recorded 805 species from his garden at Blackheath, Kent during the years 1927 - 1973. Neither of these authors specifically sought subterranean species but findings in this study indicate that gardens are rich in these species too. No doubt, a longer list of garden subterranean species could have been obtained by further effort but there would undoubtedly be a diminishing return. Not one of the species was found in all 12 gardens. Most of the species encountered were trapped in less than half of the gardens studied but it has to be noted that, when traps were set in more than one position in a garden, the catch in terms of species present varied in different positions. Thus the apparent absence ofa species from a garden may have been more due to the position(s) selected for the trap(s) rather than to a real absence. Not surprisingly, most of the beetles species trapped underground are small. In this study, 95% of the specimens belonged to species less than 5mm long and easily able to pass through a tunnel 1 mm sq in cross section. Many of the species trapped are recognised as species normally living or developing in the soil. Others live onthe surface ofthe soil orin decaying vegetation and may have found their way into traps by chance, perhaps burrowing into the soil to escape desiccation. Some, such as Carpophilus marginellus and Glischrochilus hortensis, are normally associated with sap running from tree wounds or underbark and may have been attracted to the traps by the sherry-vinegar mixture with which they were baited. Abraeus globosus normally occurs in rotten wood and it may be relevant that there were rotten logs lying on the soil near where the particular trap was set. There was considerable variation in the relative abundances of different species. This is the usual finding in surveys by trapping (see, for example, Williams, 1964; Taylor, 1978). The abundances of 499 species recorded by trapping with a flight- interception traprangedfrom one to 841 specimens (Owen, 1993); 125 species (27% ofthetotal) wererepresentedby single specimens. There does not appear to have been published a list of subterranean beetles with which this garden list can be compared but an on-going similar survey of subterraneanbeetles in woodlands inthe same general areahasproducedto-date 100 species. Some of these have occurred both in gardens and woodlands but there are apparently differences in the subterranean beetle fauna in the two habitats. Thus out SUBTERRANEANBEETLES 13 ofthe 60 species trapped in gardens, 36 have not so far been trapped in woodlands. Ofthe seven Red Data Book and Nationally Notable species found in gardens, only one -Anommatusduodecimstriatus-has turned up in woodlands. A full comparison of gardens and woodlands obviously requires more woodland trapping but it is unlikely thatall the differences already notedwill disappear. The paucity ofspecies and beetles in the one garden on fine sand is mirrored by a similar paucity in woodland on the same type of soil. Fine sand naturally packs tightly making itdifficult forbeetles topass through it. Holes made by thepassage of worms and other tunnelling creatures are not semi-permanent in sand as they are in the other types ofsoil. The greater number ofspecies from gardens on clay may be relatedtothemoisture holdingproperties ofthis type ofsoil. Five of the species trapped in gardens, viz.-, P. woUastoni, A. diecki, A. duodecimstriatus L. anophthalma and R. marqueti have an number of features in common. They lack eyes and wings and except, forP. woUastoni, have fused elytra. Apart from A. diecki, they were among the beetles trapped in greatest numbers in gardens. Three of these species -A. diecki, L. anophthalma and R. marqueti, have not so farturned up in traps in woodland while the other two turned up there in very small numbers - two and ten respectively. It thus seems that lack ofeyes and wings and fused elytra are features specialised for an underground lifestyle and that in south-east England, at least, the more specialised underground beetles are insects of gardens rather than insects of the countryside. Absence of wings must seriously interfere with natural spread of an insect and it may be that these beetles were introducedtoBritain anddistributed between gardens by human activities. The presence of a number of Red Data Book and Nationally Notable species in gardens raises an interesting conservation issue. The national status ofinsects is one of the factors used in deciding which habitats should receive priority in protection and it would seem sensible that the importance ofthis index should not be weakened by giving high status to more or less exclusively garden insects. The same argument applies to species living in man-made compost heaps. One grass-compost heap studied over a three year period was found to harbour six Red Data Book and eight Nationally Notable species, some ofwhich appearto be more orless confined to this habitat(Owen, Allen, Booth & Luff, 1997). Noteson selected species Stomis pumicatus. This was the only carabid to be trapped more than once. Little appears tobe known about it ecology but its recorded occurrence in flooddebris is consistent with a subterranean life style. The elongate mandibles could conceivably be anadaptation to seekingprey in tunnels in the soil. Parahathyscia woUastoni. This beetle was the most abundant ofthe species trapped in gardens comprising over a third ofthe total specimens. Though it was recorded from fourgardens, 917 specimens camefrom asingle trap in agarden onchalk. In gardens, it occurs nearly entirely underground; it was not among the 366 species recorded in his garden by Henderson (1945, 1946) and Allen (1953), in his very 1 14 ENTOMOLOGIST'SRECORD,VOL. 11 25.i.l999 extensive study ofgarden beetles, recorded only two specimens, both taken under cut grass. This species has been recorded from old seed potatoes (e.g. Wood, 1886) but the garden in which the 917 specimens were trapped had not been used for growing potatoes or any other root vegetables for at least a decade and the ground in which the trap was set had received only minimal cultivation for many years. Abroad, Parabathyscia forms part ofa large group ofrelated genera, many of which live in caves. As far as adaptation to underground existence goes, P. wollastoni has long been noted to lack eyes. Examination of about 20 trapped specimens revealedthatthey lackedwingsbuttheelytrawerenotfused. Alevonota aurantiaca. A single specimen ofthis species was trapped in a garden on loam at what was historically the edge ofthe North Downs. The species is known only from Dorset, South Hampshire and Surrey, where it has been found on relatively few occasions usually by sweeping in calm weather (Allen, 1991). Two specimens were caught in a flight interception trap on chalk downland (Owen, 1997b). Its appearance in an underground trap supports the view that itessentially an underground species. Acrotonaparens. This species was not recognised as British until Champion (1909) recorded a specimen fromGuildford, Surrey. Since then, ithas beennotedinother parts ofsouth and south-easternEngland and in North Wales thoughthere are few publishedrecords. Thchonyx sulcicoUis. A single specimen was trapped in a garden backing on to a large woodland area. The beetle has been recorded mostly from woodland areas though the only other example found by the author was also in a garden, at Bishop'sWaltham, Hampshire. Athous campyloides. A male and female ofthis crepuscular species was trapped in a garden on loam, along with two larvae probably of this species. The beetle is normally found atthe rootsofgrass in sandy areas. Rhizophagus parallelocollis. Sixteen specimens came from traps in three gardens. The species has long been recognised as one occurring underground, usually in association with the corpses of animals or with coffins. Enquiries, however, did not uncover any other evidence ofburials in the gardens concerned. This species has wings and the elytra are not fused. Peacock (1977), citing Horion (1960), statesthatadults cometothe surface in spring and swarm. Rhizophagus perforatus. This was one of the commonest species to trapped. It is another species recognised as a garden insect (e.g. Henderson, 1945; Allen 1950), being found usually under pieces of wood or stones or in compost. It appears regularly in small numbers in an m.v. light trap set near a compost heap in the author'sgarden. } SUBTERRANEANBEETLES 15 Table1: Beetlestakeninundergroundtrapssetingardens. Thetotalnumberofspecimenswas2240.Datacover 12gardens. Numberofgardens Numberof Species ^ - withspecies specimens CARABIDAE Clivinafossor(Linnaeus) 1 1 TrechusobtususErichson 1 1 Stomispumicatus(Panzer) 1 6 HYDROPHILIDAE Megasternumohscurum(Marsham) 3 6 Hlb1bKlUAh Abraeusglobosus(Hoffmann) 1 7 Kissisterminimus(Aube) 1 1 PTILIIDAE PtenidiumlaevigatumErichson 2 13 P.pusillum(Gyllenhal) 3 LEIODIDAE Parabathysciawollastoni(Janson) 4 950 CoprophilusstriQtulus(Fabricius) 11 1 I itiiy^lClrlUiy flllt-flcs OdlllUCl 1 1 JJ A tptrnrnvlnnti^^(JWc\c\c\ 2 I^iAlrl!UUliifilJLil\ipt.rlflc \vJlaVCIlllUlol^ 1 1I I fvfntUnlllttpi^LniurlnLrIttduffmlCV\Jvlct\\xiVfC^ltl\l\l\Ur\lT^\ 11 LjM.iilLtiJIJ1iJIJ11iLjiAIAiJ \XJl\.0\J\ji\.) 2 1J KyiniiiijiiiyiniK.\,l/ij/iiiitij ivit^owiiwt^iit'i \ yytifiiriuiir114,3 ii/it.u/ics \\jii\s:zi tA t/uMpC/Liitilu/tiky:tyryIiCPiKJnl/yfyfilCplImtfiliLlKt:y \(L\\/L\C^Lvl^dYl\l'd^ltltl\\J 9it Tnrhvn/irns:rli^nnr(^P^ivViill^ 11 1X 11 I/.fvUnltliU/.iUnliUuiS^^(Y^^Ff^a\U~\lvl^C^'l^U\^acj\ z D-3 Tcichinussubtcfrciucus(Linnaeus) i Z 3 J Callicerusrigidicornis(Erichson) 1 4 Dinaraeaangustula(Gyllenhal) 1 Plataraeahrunnea(Fabricius) 9 Philhygraelongatula(Gravenhorst) 2 Mocytafungi(Gravenhorst) 1 Acrotonaparrens(Mulsant&Rey) 1 1 Datomicranigra(Kraatz) 1 3 Athetatriangulum(Kraatz) 2 32 A.xanthopus(Thomson) 2 30 A.crassicornis(Fabricius) 2 7 A.oblita(Erichson) 2 11 AlevonotaaurantiacaFauvel 1 1 Oxypodaopaca(Gravenhorst) 1 2 1 16 ENTOMOLOGIST'SRECORD,VOL. 11 25.i.l999 Numberofgardens Numberof Species withspecies specimens PSELAPHIDAE Euplectuskarsteni(Reichenbach) 1 2 Trichonyxsulcicollis(Reichenbach) 1 •. 1 11 SCARABAEIDAE Oxyomussylvestris(Scopoli) 1 3 ELATERIDAE MelanotusvillosusGeoffroy AthouscampyloidesNewman 1 2 THROSCIDAE Trixaguscarinifrons(deBon\ou\oir) 1 2 NITIDULIDAE 1 3 CarpophilusmarginellusMotschulsky 2 .12 Glischrochilushortensis(Fourcroy) 1 RHIZOPHAGIDAE RhizophagusparallelocollisGyllenhal 3 16 R.perforatus^nc\\?.on 9 183 CRYTOPHAGIDAE Atomariatestacea(Msirsham) 3 3 A.pulchraErichson 1 1 BOTHRIDERIDAE AnommatusdieckiReitter 7 38 A.duodecimstriatus(Miiller) 9 285 ENDOMYCHIDAE Mycetaeahirta(Marsham) 1 1 LATRIDIIDAE Aridiusnodifer(Wesfwood) 2 10 Cortinicaragihhosa(Herbst) 1 1 COLYDIIDAE LangelandiaanophthalmaAube 4 162 CHRYSOMELIDAE Phyllotretanigripes(Fabricius) 1 4 CURCULIONIDAE Otiorhynchussingularis(Linnaeus) 1 1 Barypeithesaraneiformis(Schrank) 3 57 B.pellucidus(Boheman) 8 85 Raymondionymusmarqueti(Aub.) 10 193 SUBTERRANEANBEETLES 17 Anommatusdiecki. This species isknowntolackeyes andexaminationofanumberof examples showed that it also lacked wings and has fused elytra. Until recently, this species wasknown only from Cheshire where the firstrecognised British specimens were found in 1984 (Eccles & Bowestead, 1986). Subsequently, as noted by Booth & Owen (1997), a few specimens taken prior to its discovery in Cheshire were discovered among material in The Natural History Museum, London and specimens havebeenfoundrecently ingardensinKentandEastSussex. Anommatus duodecimstriatus. This was one of the commonest beetles trapped with 285 examples recorded from nine gardens. Another eye-less species, it also lacks wings and has fusedelytra. In Britain, it has been found in various localities in the southern half of England, frequently in the shrivelled skins of seed potatoes remaining in the soil after producing the potato plant. It has also been found in decomposing vegetable debris (Allen, 1954), under bark and at tree roots. It occursregularly in theremains ofseedpotatoes inagarden allotment situatednear some ofthegardens studied. Langelandia anophthalma. There were 162 examples recorded from four gardens but it has yet to be obtained by trapping in woodlands. It is yet another species lacking eyes and wings and with fused elytra. This species was first found in Britain in the remains of seed potatoes at St Peters in Kent (Wood, 1886). Wood recorded that the seed potatoes came from Guernsey and discussed the possibility thatthe beetle might have been imported. At the time it was noted in Europe to be found principally in gardens under pieces of wood or wooden objects such as barrels lying on the ground. As in the case ofthe last species, it has been recorded mainly from the remains ofseed potatoes but it has also been found in association witholdroots. There are publishedrecords forsites in southern England stretching from Kent to Cornwall (e.g. Wood, 1886; Allen, 1937; Allen, 1954; Booth, 1977; Denton, 1997). Nearly all ofthese records have been for essentially synanthropic situations. It is perhaps relevant that many specimens ofthe beetle were found on the under-surface oflarge logs lying on the ground in the author's garden in the 18 months immediately preceding the first use in the gardenofundergroundtraps. Barypeithes araneiformis and B. pellucidus. These two polyphagous, ground- dwelling weevils were trapped in relatively large numbers. They have eyes but are without wings and have fused elytra. Their occurrence in underground traps indicate that they burrow below the surfacepossibly forlaying eggs inroots. Raymondionymus marqueti. This is another species which was trapped in some numbers in gardens but not in woodlands. The species is known to lack eyes (Osella, 1977). Examination ofa number ofspecimens trapped in the Epsom area showed that they also lacked wings and have fused elytra. It appears to be an introduced species which was first noted at Kew Gardens, Richmond (Williams, 1968) and lateratBromley, Kent (Thompson, 1995). Anaccountofits presence in north-westSurrey has already beenpublished (Owen, 1997a). 1 s 18 ENTOMOLOGIST'SRECORD,VOL. 11 25.i.l999 Type Number Trapping Total Number Average number of effort numberof ofbeetles ofspecies ofsoil gardens (trap-weeks) beetles pertrap-week pergarden Chalk 4 309 1708 5.8 14.5 Finesand 1 30 1 1 Loam 5 71 206 2.9 7.4 Clay 2 86 325 3.5 17.5 Table2: Influenceofsoiltypeonnumbersofbeetlesandnumbersofspeciestrappedingardens. Commentson the trapping procedure In general, the trapping procedure used in thus study has proved simple andreliable, both in the author's hands and in the hands of colleagues. Two traps suffered interference from animals, being torn out ofthe ground and chewed. This happened once in the author's garden when he forgot to replace a stone covering the mouth of the trap which allowed it to be dug up, presumably by a fox as it would not have been accessible to a dog. On the second occasion, the trap dug up was in a wood accessible to dogs and foxes. It had been covered with a stone but, presumably, this was not sufficiently heavy. Although no trouble has been experienced in lifting up traps and re-siting them, twominormodifications make the trap stronger. Firstly, the mouth ofthetrapcanbe strengthened by setting a short (1cm) section ofrigid pipe into the upper end ofthe netting cylinder, fixing this in place with a rim of"Blue Tac" adhesive (Bostik Ltd, Leicester) and winding PVC self-adhesive tape round the outside. Secondly, by means of a curved needle, a length of fine, plastic covered wire can be threaded vertically through both layers of netting where they overlap to help maintain its cylindrical shape. "Netlon" greenhouse shading (Netlon Ltd., Blackburn) has proved a satisfactory alternative to nylon mesh but traps longer than 20cm made with "Netlon" mesh require a short (1cm) section ofrigid pipe set inside half-way down, andfixedas forthe strengthenedrim, tomaintainthenetting in acylindrical shape. Acknowledgements I must thank the following for allowing me access to their gardens to set traps and forhelp in theirmanagement: Mrs N. Bowman, DrH. Cleeve, SirJohnDacie, MrG. du Heaume, Dr A. Fleck, MrW. Lawrence, Mrs J. and MasterT. Lee, MrT. Owen, DrJ. Walsh, DrI.White andDrH. Wilcox, Lastly, I mustthankmy wifeforherhelp inconstructingthetraps and in servicingthemonmany occasions References Allen, A.A., 1937. A new locality forLangelandia anophthalma Aube. Entomologist's Rec. J. Var.49:60 - , 1953. The Coleoptera ofa suburban garden - parts 5 - Clavicomia (Part 1) Entomologist' Rec.J. Var.65: 225 -231. . ss SUBTERRANEANBEETLES 19 - 1954. 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Denton,J.S., 1997.LangelandiaanophthalmaAube(Colydiidae)inMiddlesex.Coleopterist5: 88 Eccles,T. M. andBowestead, S., 1987.AnommatusdieckiReitter(Coleoptera: Cerylonidae) new toBritain.Entomologist'sGaz.38: 225-227. Henderson, J.L., 1945. The beetles ofa suburban London garden in Surrey. Entomologist's mon. Mag.81:63-66. -, 1946.MorebeetlesofaLondonsuburbangardeninSurrey.Entomologist'smon.Mag.82.-38-39. Horion,A., 1960.FaunistikderMitteleuropdischenKdfer7: 346ppBodensee Hyman, P.S. andParsons, M.S., 1992 (pt. 1), 1994 (pt. 2).A reviewofthescarceandthreatened ColeopteraofGreatBritain. UKJointNatureConservationCommittee,Peterborough Osella, G., 1977. Revisione della sotofamiglia Raymondionyminae (Coleoptera. Curculionidae). MemoriedelMuseocivicodiStoria naturaledi Verona fllaseries), Sezione SciencedellaVita No.l. Owen, J.A., 1993. Use ofa flight-interception trap in studying the beetle faunaofa Surrey wood overathreeyearperiod.Entomologist112:141-160 -, 1995. 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Williams, S.A., 1968. Raymondionymus marqueti (Aube) typical form in Surrey. Entomologist' mon.Mag. 104: 112. Wood, T., 1886. Langelandia anophthalma, Aube at St. Peter's, Kent; a species of Coleoptera newtoBritain.Entomologist'smon.Mag.23: 93.