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NOTES ON SUFFOLK GALL INDUCING HYMENOPTERA INCLUDING ISOCOLUS SCABIOSAE (GIRAUD, 1859)

(HYMENOPTERA: CYNIPIDAE) AND OPHELIMUS ? MASKELLI (ASHMEAD, 1900) (HYMENOPTERA: EULOPHIDAE)

NEW TO THE COUNTY

JERRY BOWDREY

Abstract Two new Hymenopteran gall inducers are added to the Suffolk list and additional, recent records of other gall-inducing Cynipidae are given.

Introduction Recent field work has added two new species of gall-inducing Hymenoptera to the Suffolk list. These include a previously overlooked native species as well as a new UK coloniser. Unless otherwise stated, all records are the author’s.

Cynipidae: Aulacidinae A visit to Clare Country Park (TL7745) on 26 September 2009 provided the opportunity to search for galls on Centaurea scabiosa (Greater Knapweed), a plant that is frequent along the old railway line track at that site. There are currently three cynipid species recorded as galling this plant in Britain, Phanacis centaureae which galls the stems internally and was also present at Clare, Isocolus fitchii galling the base of the stem and I. scabiosae galling both stems and bracts.

Isocolus scabiosae (Giraud, 1859) form rogenhoferi Wachtl, 1880 Several bract galls induced by I. scabiosae f. rogenhoferi were located in seedheads of C. scabiosa at Clare. They are revealed by scraping aside the ripe seeds to expose the inner surface of the bracts.

I. scabiosae is an unusual gall wasp in that it is capable of inducing two very different types of gall on different parts of the host plant.

One type of gall is multilocular and forms an irregular swelling at the base of the stem of the plant, the other is unilocular and occurs in the involucral bracts of the flower. The bract gall was formerly known as I. rogenhoferi (Eady & Quinlan, 1963), but this has now been downgraded to the status of a form (Nieves-Aldrey, 2001).

Galled bracts are detectable in the flower heads of the plant as hard swellings on the inside wall of the flower. The galls are hard and shiny, measuring about 5 mm × 3 mm and are situated at the base of the bract (Figs. 1 & 2 show a fresh gall and one with the emergence hole of I. scabiosae).

The galls are not usually visible from the outside, although they may cause slight irregular distortion of the flower in some cases (pers. ob.). This cryptic habit probably results in the species being under-recorded.

The gall wasp usually emerges in June or July of the following year, the gall remaining attached to the dead flower head throughout the winter. Occasionally, however, emergence holes can be found in galls in August and September of the same year as gall formation (Fig. 3). These have been attributed to chalcid parasitoids which more usually emerge the following year (Niblett, 1942).

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Morley (1931, 1935) does not record this species from Suffolk and there are no specimens in his collection at Ipswich Museum.

Figure 1. Gall showing emergence hole of

Isocolus scabiosae

Figure 2. Emergence hole of I. scabiosae

Figure 3. Bracts showing parasitoid emergence holes.

Aulacidea hieracii (Linnaeus, 1758) A visit to North Denes Lowestoft (TM5496) on 11 October 2009 turned up galls of Aulacidea hieracii on stems of Hieracium sp. growing on the dunes. This gall varies in appearance, especially the degree of hairiness, in accordance with the species of Hieracium galled. The North Denes examples were sparsely hairy and quite slender.

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Aulacidea pilosellae (Kieffer, 1901) In my paper in the last Transactions (Bowdrey, 2009), it was stated that Aulacidea pilosellae had not yet been found in west Suffolk. Michael Chinery kindly wrote to say that he had found the gall in some numbers at Maidscross Hill, Lakenheath (TL7282) in 2008 and again in 2009.

Diastrophus rubi (Bouché, 1834) Nigel Cuming found an old gall of Diastrophus rubi on Rubus fruticosus agg. (Blackberry) on the disused railway line path at Aldeburgh (TM462588) in August 2009. The wasp seems to prefer to gall stems in the centre of blackberry thickets, making them difficult to find. They are sometimes exposed when the edges of footpaths are cut back.

Phanacis hypochoeridis (Kieffer,1887) Several galls were found on cat’s ear (Hypochaeris radicata) at North Denes Lowestoft (TM5496) on 11 October 2009.

Cynipidae: Rhoditini

Diplolepis spinosissimae (Giraud, 1859) The colony of Diplolepis spinosissimae reported from a garden near Westleton Common (Bowdrey, loc. cit) continues to thrive and galls were observed again in July 2010 by Nigel Cuming. A local resident informed Nigel that the wasp had spread to Rosa spinosissima in another garden in the village.

Galls of this species were again found in good numbers on Rosa canina agg. at Stutton in June 2010 (Bowdrey, loc. cit.)

Cynipidae: Cynipinae

Andricus callidoma (Hartig, 1841) Following high winds in early May 2010 a large number of leaves and twigs were broken off the trees in Christchurch Park, Ipswich. One such twig from pedunculate oak (Quercus robur), found on 10 May 2010, bore male catkins, one of which had tiny cotton-wool like tufts growing from it. Andricus quercusramuli the Cotton-wool gall, was found at the park last year and at first sight the present gall resembled an early stage of the gall of this species. However, after several days the galls (Plate 4) had grown no larger and cynipid wasps emerged. These proved to be the sexual generation of Andricus callidoma form cirratus (previously known as Andricus cirratus).

In A. callidoma the gall is up to 5 mm across and from one to six chambers are visible, whilst in A. quercusramuli there are up to twenty chambers completely concealed in the cotton wool-like growth, the whole gall being up to 20 mm across.

This is an enigmatic and seldom seen species which is often quoted as inhabiting the higher branches of mature oaks (Redfern & Shirley, 2002). It does, however, occasionally occur lower down as was the case at Little Bentley in Essex (pers. obs.) and also on Mull in Scotland (Jennings, 2010).

Morley (1935) recorded the species from Tuddenham on 22 May 1911 (as A. cirratus) and stated that it was ‘apparently rare’. More recently, Redfern & Shirley (loc. cit.) also consider this gall to be rare.

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The gall of the agamic generation is perhaps more readily seen, as it comprises a stalked, spindle-shaped, unilocular gall affecting lateral buds of Quercus robur, although no records of this generation in Suffolk have been traced as yet.

Chalcidoidea, Eulophidae

Ophelimus (?maskelli) (Ashmead, 1900) Galls induced by other families of Hymenoptera are less frequent, but a new species of Ophelimus galling Eucalyptus was added to the county list by Nigel Cuming. Following examination of galls on Eucalyptus from Westcliff in south Essex (Bowdrey, in press), Nigel searched trees in Aldeburgh and was successful in locating a large population at TM461574 on 22 June 2010. This would appear to be the first record of the species from Suffolk.

The Ophelimini is a small tribe of Chalcidoidea belonging to the family Eulophidae and native only to Australia (La Salle, 2005). Females lay eggs on new eucalyptus foliage in early summer, and the larvae develop within the leaves, although the raised galls do not become particularly obvious until the following spring, when the mature larvae pupate within the galls

It is likely that the Ophelimus may have entered Southern Europe via the horticultural trade in eucalypts and have since spread northwards. As the Ophelimini are poorly known, the species identification of the British population remains provisional (Fig. 4).

Figure 4. Ophelimus galling Eucalyptus

Galls attributed to this species were first reported in Britain from Lambeth in London, in April 2005 (Tilbury & Jukes, 2006). On April 3 2007 Badmin (2008) noticed a specimen tree of Eucalyptus gunnii, heavily infested with galls, at Gunnersbury Cemetery in west London.

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The first record for Essex appears to be from Hyde Hall Gardens at Rettendon (TQ7899), where galls were found on a long-leaved eucalypt on 1 June 2008 (Badmin, loc. cit.). In May 2010, further galls were found at Westcliff (TQ8686), in the south-east of the county.

Heavy infestations of galls can lead to leaf loss and discolouration. Further information is available on-line from CSL (2007).

Acknowledgements Thanks to Nigel Cuming for his records of Diastrophus rubi, Ophelimus galls and checking on the Westleton D. spinosissimae population and to Michael Chinery for his record of A. pilosellae from west Suffolk.

References Badmin, J. (2008). Spread of Ophelimus ? maskelli Ashmead (Hymenoptera:

Eulophidae) in south-east England. Br.J.Ent.Nat.Hist. 21: 147. CSL (2007). CSL pest risk analysis for Ophelimus maskelli.

www.fera.defra.gov.uk/plants/plantHealth/...ophelimusMaskelli.pdf Bowdrey, J. (2009). Notes on some Suffolk gall wasps (Hymenoptera:

Cynipidae).Trans. Suffolk Nat. Soc. 45: 35–41. Eady, R. D. & Quinlan, J. (1963). Hymenoptera: Cynipoidea. London , Royal

Entomological Society. (Handbooks for the Identification of British Insects 8(1a)).

Jennings, M. T. (2010). Some records of Cynipidae (Hym.) and associated parasitoids (Hym. Chalcidoidea) from Lochbuie, Isle of Mull, Scotland. Entomologist’s Monthly Magazine 146: 126–7.

Morley, C. (1931). A synopsis of the British hymenopterous family Cynipidae. Entomologist LXIV, 206–210.

Morley, C. (1935).The Hymenoptera of Suffolk. Part 1. Trans. Suffolk Nat. Soc. 3: 17–52.

La Salle, J. (2005). Biology of gall inducers and evolution of gall induction in Chalcidoidea (Hymenoptera: Eulophidae, Eurytomidae, Pteromalidae, Tanaostigmatidae, Torymidae). in Biology, Ecology and evolution of gall-inducing arthropods Vol. 2 edited by Raman, A. et al. Enfield, Science Publishers.

Niblett, M. (1942). The cynipid genus Isocolus (Hymen.) Proc. Trans. S. Lond. Nat. Hist. Soc. 1941–2: 37–39.

Nieves-Aldrey, J. L. (2001). Hymenoptera Cynipidae. Madrid, Museo Nacional de Ciencias Superior de Investigaciones Cientificas. (Fauna Iberica 16).

Redfern, M. & Shirley, P. R. (2002). British plant galls. Preston Montford, Field Studies Council.

Tilbury, C. & Jukes, M. (2006). Ophelimus ?maskelli: a new gall-causing eulophid wasp (Hymenoptera: Chalcidoidea) on Eucalyptus in London. Cecidology 21: 90–91.

Jerry Bowdrey Colchester & Ipswich Museums Service, 14, Ryegate Road, Colchester Essex CO11YG Email: jerry.bowdrey@colchester.gov.uk

Plate 4: Galls of Andricus callidoma (Hartig) on Oak Quercus robur catkins, Christchurch Park, Ipswich (p. 36).

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