Notes on the Suffolk list of Coleoptera: 6 Scolytidae - an addendum; Platypodidae

65 NOTES ON T H E SUFFOLK LIST OF C O L E O P T E R A : 6 SCOLYTIDAE - AN A D D E N D U M ; P L A T Y P O D I D A E DAVID R. NASH This paper up-dates my earlier notes on Scolytidae (Nash, 1984) bringing forward a further species of bark beetle as new to Suffolk, providing the second county record for another and adding the closely-related Piatypus cylindrus ( Fabricius) to the county list. Most authorities (e.g. Crowson, 1981, Lawrence & Newton, 1995) now consider the Scolytidac and Platypodidae to be subfamilies of the Curculionidae; for consistency with the original paper in this series, however, their pre-Crowson status is maintained.

SCOLYTIDAE Polygraphus poligraphus (Linnaeus) The Suffolk records of this rare species were reviewed and discussed in my earlier paper (loc .cit.), the beetle last being recorded at Halesworth in 1937 (Donisthorpe, 1937).

Whilst visiting the Ickworth Estate to record beetles in July, 1998 the foresters asked if I could ascertain what was killing some Picea abies (Norway Spruce) in a small plantation on the northern edge of the estate. Three beetles from the affected trees were subsequently sent to me for identification and werc immediately recognised as Polygraphus. I visited the site of the infestation (TL/8163) on September 22nd and evidence of beetle attack was found in several Spruce poles. A few adult Polygraphus were found as well as many scolytid larvae some of which were taken for rearing. Polygraphus began emerging in numbers from the infested bark during October and November as well as a pair of another scolytid, the common Hylurgops palliatus (Gyllenhal).

I have also recently identified a specimen of Polygraphus taken by my friend Martin Collier at his home at Syleham near Eye (TM2179) in August, 1998. Bevan (1987) rates the damage caused by Polygraphus as important, causing significant loss of increment or value. It should be noted, however, that the beetle usually attacks root-rotten or droughted trees i.e. ones whose commercial value is already affected prior to the infestation; the trees attacked at Ickworth had been affected by the drought during 1997. Forest Enterprise have been notified of the outbreak.

Ernoporicus caucasicus Lindemann Ernoporicus caucasicus is a tiny bark beetle which breeds in this country in the thinner branches of Tilia_cordata (Small-leaved Lime) and T. x vulgaris (Common Lime). It was added to the British list (as Ernoporus caucasicus) on the basis of speeimens taken at Moccas Park, Herefordshire in 1954 (Allen, 1970) and is afforded RDB1 (Endangered) status in Hyman (1992). Until that time, only two species of Ernoporus as then defined were afforded a place on the British list viz. tiliae (Panzer) and fagi (Fabricius). Ernoporus tiliae, the rarest of the three species and not known from Suffolk, is also a RDB1 species, and appears in this country to be restricted to T. cordata. Ernoporicus fagi was new to Suffolk when recorded (as Ernoporus fagi) in my original paper (vide Pfeffer, 1994 for the nomcnclatorial changes involving these species).

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On September 14th, 1997, Messrs T. Dräne and H. Mendel visited Groton Wood (TL/9743) to look for the two Tilia-feeding species. They found extensive colonisation of the over-mature T. cordata coppice stools by E. caucasicus. Dead and living beetles were present in both the Standing coppice poles and in brashings of between 3 and 10 cm in diameter. Believing the species could occur in suitable habitats elsewhere in the county but that it had been previously overlooked because of its diminutive size (1-5—2 mm) and host specificity, I visited Cutler's Wood, Freston (TM/1538) on 27th April, 1999 to search for it in the Strip of T. cordata on the wood's western edge. Shotholes were soon found in the lopped and dead branches on and under these trees, and eventually an adult was discovered on the underside of a 5 cm thick branch lying on the ground. Many examples were reared from a piece of this branch over the following week. Visiting the Ickworth Estate a week later on 5th May, I collected T. x vulgaris bark with shotholes from a 6 - 7 cm diameter fallen branch in Horringer Park (TL/8162) and infested T. cordata branches (2 cm diameter) from Lownde Wood (TL/8059). Both samples produced adults over the following weeks. Unlike most bark beetles which complete their life cycle only in sappy, freshly fallen or felled timber, Ernoporicus caucasicus appears able to continue to maintain its lifecycle in quite dry branches which have been dead for several years.

PLATYPODIDAE Piatypus cylindrus (Fabricius) The Platypodidae are well-characterised, having the head not concealed from above by the prothorax, the thorax sides emarginate, the elytra elongate and cylindrical and the first larsal segment much longer than joints 2-4 together (Duffey, 1953). Almost all platypodids and some scolytids (including our species of Xyloterus and Xyleborus) are popularly known as Ambrosia beetles because their larvae feed, not on wood, but on a sticky lining in their tunnels which the naturalist Schmidberger in 1836 likened to 'Ambrosia' or 'food of the Gods' and which Hartig in 1844 recognised as fungal growth. This fungus is cultivated within a symbiotic relationship, the beetles having specific cavities (myeangia of Batra, 1963), usually on the thorax, to carry the fungal spores upon which they depend from tree to tree. Some platypodids are economically important timber pests because their attacks, although not causing significant structural injury, spoil the appearance of the timber. Apart from the tunnels cut by the beetles, secondary damage consisting of staining of the wood in a longitudinal direction on each side of the tunnels, is often more important than the tunnels themselves (Munro, 1930; Anon, 1940).

Piatypus cylindrus Fabricius is the only member of the family indigenous to Britain although three other species are sometimes imported from the tropics viz. parallelus (Fabricius) (= linearis Stephens), curtus (Chapuis) and hintzi Schaufuss (= penetralis Sampson; solutus Schedl) (Aitken, 1975); there is also some evidence that parallelus may be breeding in the open in this country (Allen, 1976; 1985).

The life history of P. cylindrus in Britain was first described in detail by Chapman (1870) and later by Baker (1956). (It should be noted, in passing, that Fowler (1891: 450) cites the reference to Chapman's paper incorrectly and this

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Oak Pinhole Borer Piatypus cylindrus (Fabricius) c? error is repeated in Munro (1926: 74) who had obviously relied on Fowler's abridged Version rather than Consulting the fĂźll text). In July and August, freshly emerged males are attracted by the fermenting sap of a recently cut or fallen trunk and commence boring into the solid wood. Quercus (Oak) and Fagus (Beech) are most commonly chosen but also Fraxinus (Ash), Ulmus (Elm), and Castanea sativa (Sweet Chestnut); on the continent the beetle has also been recorded from Pyrus pyraster (Pear), Sorbus aucuparia (Mountain Ash), Alnus glutinosa (Alder) and Tilia spp. (Lime) (Schedl, 1981) as well as

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Prunus avium (Wild Cherry) (Balachowsky, 1949). When a newly-construcled burrow is observed by a female, shc enters and, if acceptable to its occupant, they emerge and copulate on the surface of the trunk. The female then enters the burrow, followed by the male and she now takes over the boring, with the male removing the bore dust and ejecting it. This bore dust is white and splintery and has not been passed through the gut of the beetle. As can be seen from the figure, the anterior femora of the beetle are extremely broad (hence the generic name) and the front tibiae are diagonally ridged externally, enabling the beetle to get a firm hold on the wall of the tunnel when using the powerful femoral muscles to push itself backwards. Beetles dug out of their tunnels usually have the long slender tarsi reduced, often to only half the basal joints.

Chapman (Zoe. cit.), concluded that this damage was caused by the jerk which ensued after a tough splinter of wood at which the beetle was gnawing, suddenly gave way, causing the beetle to be thrown backwards in its tunnel for a distance equal to one third its own length. The beetles, which do not leave their burrows once constructed, appear not to be inconvenienced in any way by this damage and can move very actively along their tunnels on their stumps.

Eggs are laid in the burrows throughout the early autumn and into winter. The tunnels are straight, narrow and of uniform width, varying from a relatively short, unbranched tunnel some 7 cm in length to a complicated branching system of over 180 cm. These straight, narrow tunnels have given rise to the other populär name for the smaller Ambrosia beetles - Pinhole Borers, Piatypus cylindrus being referred to in forestry circles as the Oak Pinhole Borer. (The larger tropical species are known as Shothole borers). The newlyhatched larvae are equipped with two rows of long stiff bristles on their sides which enable them to move up and down their burrows with a wave-like motion as they feed on the lining of the tunnels which is composed of tiny wood fragments on which the fungus grows. Baker (loc. cit.) showed that the fungal lining of these burrows actually comprised three species - two ascomycetes and a yeast-like endomycete. Fungoid wood fragments are passed and re-passed through the larval gut and the adult beetles eject the frass and bitten-off wood splinters through the burrow opening. These materials often accumulate around the borehole, sometimes completely burying the mouth of the burrow. In Wiltshire, I have found burrows in oak and beech where this frass etc. has been wetted by rain and a tubulär extension of the burrow mouth has formed, protruding 10 mm or more from the borehole. Larvae and adults become almost dormant throughout the winter but, early in spring, the colonies become active again with considerable frass once more being ejected. In April and May, their role concluded, the parent beetles die and the fßll grown larvae pupate in the sides of the burrows, the new generation emerging in late summer.

Whilst recording at Horringer Park, Ickworth (TL/8162) on 22nd September, 1998 I came across a pile of large, sawn-up oak logs derived from a recently fallen bough, containing fresh boreholes with fibrous shavings hanging from them. Not having my axe with me, I was unable to dig out any adult beetles from the burrows because of the hardness of the wood. Visiting a timber storage site some lA km distant, however, I came upon a mature Acer

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pseudoplatanus (Sycamore) trunk wilh thc charactcristic borcholes oncc again and this lime was successful in digging oul a singlc male Piatypus cylindrus.

Sycamorc appears to be a previously unrccorded hosl both here and on thc continenl.

Piatypus cylindrus is typically a species of ancienl broad-leaved woodland and pasture-woodland. In Fowler's day thc species was considcred local and rare. Its distribution currcntly is right across the southern counties and into southern Wales with records from thc Midlands, the North East, Dyfed-Powys and North Wales. Ii is accorded Notable B status in Hyman (op. cit.) i.e. thought to occur in between 31 and 100 10-km squares of the National Grid. It appears to have become more numerous in rccent years turning up in nondescript siles as well as occurring more commonly in its well-known strongholds e.g. thc Forest of Dean, but whether it is extending its ränge is difficult to assess. The nearest locality to Ickworth known to me for Piatypus is Epping Forest where I met with it in May, 1985. It is not, at present, recorded from Norfolk (M. Collier, pers. comm.). Whether Piatypus is an extremcly localised and rare species which has bcen overlooked in Suffolk up until now or is a recent arrival remains, for the present, sub judice.

Acknowledgments I thank Tony Dräne for providing details of all his unpublished captures of E. caucasicus and for allowing me to publish the Groton record; Kcith Alexander of Thc National Trust for permission to record at Ickworth Park; Mr. S. Paul for permission to record at Cutler's Wood; John Read for his finc drawing of Piatypus; Martin Collier, Norfolk Coleoptera Recorder, for allowing mc to include his record of Polygraphus and confirming that there were no Norfolk records of Piatypus; Nigel Mackinnon and Simon Kroon, foresters at Ickworth, for their helpful co-operation and for trying to ensure protection of the Piatypus sites; the Suffolk Naturalists' Society for awarding a Morley bursary to support my studies.

References Aitken, A. D. (1975). Insect Travellers. 1: Coleoptera. M.A.F.F. Agricultural Development and Advisory Service Pest Infestation Control Laboratory.

Technical Bulletin 31. HMSO. London.

Allen, A. A. (1970). Ernoporus caucasicus Lind, and Leperisinus orni Fuchs (Col., Scolytidae) in Britain. Entomologist's mon. Mag., 105: 245-249.

Allen, A. A. (1976). Piatypus parallelus F. (= linearis Steph.) (Col.; Scolytidae) Rccaptured in Britain aftcr 150 Years. Entomologist's Ree. J. War., 88: 57-58.

Allen, A. A. (1985). Piatypus parallelus (F.) (Col., Scolytidae) again capturcd at light in S. E. London. Entomologist's mon. Mag., 121: 141.

Anon. (1940). Beetles injurious to timber and furniture. Forest Products Research Bulletin No. 19. Department of Scientific and Industrial Research. London: HMSO..

Baker, J. M. (1956). Investigations on the Oak Pinhole Borer Piatypus cylindrus Fab. A progress report. British Wood Preserving Association Convention Record (Not seen; citcd in Hickin, 1963).

Trans. Suffolk Nat. Soc. 35

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Suffolk

70

Natural

History,

Vol. 35

Balachowsky, A. (1949). Colcopteres Scolytides. Faune de France, 50. Paris: Librairie de la Faculte des Sciences.

Batra, L. R. (1963). Ecology of ambrosia fungi and their transmission by beetles. Trans. Kans. Acad. Sei. 66: 2 1 3 - 2 3 6 (Not seen; citcd in C r o w s o n , 1981).

Bevan, D. (1987). Forest Insects - A guide to insects feeding on trees in Britain. H a n d b o o k 1. Forestry C o m m i s s i o n . London: H M S O .

C h a p m a n , T. A. (1870). O n the habits of Piatypus cylindrus, Fab. Entomologist's mon Mag., 103-106; 132-135.

C r o w s o n , R. A. (1981). The biology of the Coleoptera.

London: A c a d e m i c Press.

Donisthorpe, H. (1937). A rare boring-beetle. Trans. Suffolk Nat. Soc., 3: 284.

D u f f e y , E. A. J. (1953). Coleoptera. Scolytidae and Platypodidae.

Handbk.

Ident. Br. Insects V. Part 15. Royal Entomological Society of London.

Fowler, W. W „ (1891). The Coleoptera ofthe British Islands. Vol. 5. L o n d o n : R e e v e and Co. Hickin, N. E. (1963). The insect factor in wood decay. L o n d o n : Hutchinson & Co. H y m a n , P. S. (revised Parsons, M. S.) (1992). A review ofthe scarce and threatened Coleoptera of Greatßritain Part 1. U.K. Nature Conservation: 3. Peterborough: Joint Nature Conservation Committee.

L a w r e n c e , J. F. & N e w t o n , A . F. (1995). Families and s u b f a m i l i e s of Coleoptera (with selected genera, notes, references and data on familyg r o u p names) in Pakaluk, J. & Slipinski, S. A. (eds.) Biology, phylogeny and Classification of Coleoptera Vol. 2. Warsaw: M u z e u m i Instytut Zoologii.

M u n r o , J. W. (1926). British hark beetles. London: H M S O .

M u n r o , J. W . (1930). Beetles injurious to timber. Forestry C o m m i s s i o n Bulletin No. 9. L o n d o n : H M S O .

N a s h , D. R. (1984). N o t e s on the S u f f o l k list of Coleoptera: 4 - Scolytidae.

Trans. Suffolk Nat. Soc., 20: 3 2 - 3 7 .

P f e f f e r , A. (1994). Familie Scolytidae in Lohse, G. A. & Lucht, W. H., Die Käfer Mitteleuropas 3. S u p p l e m e n t b a n d mit Katalogteil. Goecke & Evers.

Krefeld.

Schcdl, K. E. (1981). Familie: Platypodidae in Freude, H „ Harde, K. W. & Lohse, G. A. Die Käfer Mitteleuropas.

B a n d 10. G o c c k e & Evers. Krefeld.

D a v i d R. Nash 3 C h u r c h Lane Brantham Suffolk C O l l 1PU

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