GALL RECORDER’S REPORT 2022, INCLUDING THE MITES ACERIA ONONIDIS AND CECIDOPHYOPSIS MALPIGHIANUS PROVISIONALLY RECORDED AS NEW TO SUFFOLK AND THE HYMENOPTERAN PARASITOID PEDIOBIUS ROTUNDATUS NEW TO THE COUNTY JERRY BOWDREY
Introduction
Gall inducers continue to be discovered new to Britain, some arriving naturally and others being inadvertently introduced, sometimes via the horticultural trade and in spite of plant health certification. Many of these newly established species will be covered in the third edition of the Field Studies Council publication ‘British plant galls’ by Redfern, Shirley and Bloxham, due out in 2023.
As well as these new arrivals, our knowledge of the distribution of species already established in Suffolk continues to grow. Some of the more significant records for the year are listed below under their relevant groups. All records, images and identifications are the author’s.
Notable records for 2022
Insecta
Diptera: Cecidomyiidae (Gall midges)
Dasineura kiefferi Marchal
This gall midge affects the flowers of ivy (Hedera helix) and was reported as new to Suffolk in 2020 (Bowdrey, 2021). Several galled flowers were found in the churchyard at Iken (TM411566) on 21.ix.2022, JPB. As previously mentioned, this gall is probably very under-recorded.
Hymenoptera: Cynipidae (Gall wasps)
Andricus callidoma (Hartig)
The sexual generation of this species produces small catkin galls on Quercus robur which resemble wisps of cotton wool. It is seldom found and was thought to be confined to the tops of mature trees; however, galls were found at both Ickworth Park (TL812611) on 3.v.2021 and Minsmere blocks (TM476646) on 21.v.2022 (Fig. 1) and in both cases were located only a couple of metres above the ground. This gall might be confused with the early stages of Andricus quercusramuli, but this gall first appears later in May when A. callidoma adults have already emerged.
Andricus lucidus (Hartig) (Hedgehog gall)
Popularly known as the hedgehog gall, due to its spiny agamic generation gall, this species was first reported in Suffolk from Benhall (Bowdrey, 2019). Four galls were found on Quercus robur at Knodishall churchyard (TM425619) on 13.iv.2022. This species seems to have spread more slowly than some of the other new colonists and there are still no Suffolk records of the sexual generation or its gall on catkins of Quercus cerris (Turkey Oak).
Andricus paradoxus (Radoszkowski)
This agamic generation bud gall on Quercus robur is considered to be uncommon (Redfern et al., 2011), but its sexual generation catkin gall on the same host is even rarer and may not yet have been recorded in Britain. Two agamic galls were found at Raydon (TM480788) on a roadside oak near the car parking area for Raydon Wood Nature Reserve on 17.v.2022 (Fig. 2).
Plagiotrochus quercusilicis (F.)
A Mediterranean species galling Quercus ilex and first recorded in Suffolk from its sexual generation gall (Bowdrey, 2018). After a period of scarcity, galls were again found at Orford Castle (TM420499) on 2.vi.2022. However, some galls collected at Curlew Green, Kelsale-cum-Carlton (TM380653) on 28.vi.2021 later produced some unexpected emergences in the form of the chalcid Pediobius rotundatus (Fonscolombe) a parasitoid which proved to be new to Britain (Jennings & Bowdrey, 2022) and is therefore, also new to Suffolk.
Acari: Eriophyoidea (Gall mites)
Due to the minute size of their inducers, the field identification of mite galls is, by necessity, based on the response of the host plant, rather than on the mites themselves. For this reason, many older records are difficult to authenticate. Two mite galls, apparently new to the County, are provisionally added to the Suffolk list, but are not verified by specialist examination of the mites themselves.
Aceria ononidis (Canestrini) New to Suffolk
Stunted plants, identified as Ononis repens (Common Restharrow) and growing on dry grassland at Sizewell, just south of Minsmere blocks (TM475644), were at first thought to be suffering from the effects of the severe drought experienced during summer 2022. However, closer examination showed that the leaves and flower buds at the shoot tips were smaller than normal and abnormally hairy, contrasting with more normal plants growing nearby (Fig. 3). The galls were identified from Redfern et al. (2011) as being induced by the mite
Aceria ononidis, a species probably new to Suffolk. In addition, a young larva of Aplasta ononaria (Rest Harrow) (Lepidoptera: Geometridae) was found feeding amongst the galled shoots.
Cecidophyopsis malpighianus (Canestrini and Massalongo) New to Suffolk
This gall mite affects the flowers of Laurus nobilis (Bay) causing them to swell to up to 10x their normal size (Fig. 4). Enlarged flowers were noticed on a bay tree growing in a front garden in St. Edmunds Road, Southwold (TM498766) on 10.xi.2022. Microscopic examination revealed elongate mites (Fig. 4) amongst white hairs within the buds.
Originally described from Italy, the British status of the species is reviewed by Spooner (2007).
Fungi
Ustilaginales: Ustilaginaceae (Smut fungi)
Ustilago maydis (DC.) Corda (Maize smut)
Walking the coast path from Snape
Maltings to Iken (TM3956) on 21.ix.2022, a field of Zea mays (Maize) adjacent to the footpath was seen to bear some rather strange looking cobs. Closer examination showed each seed was distorted, silvery white and swollen, whilst older cobs showed masses of black spores. The galls were identified from Redfern et al. (2011) as being induced by the smut fungus Ustilago maydis (Fig. 5).
In Central America the young galls are considered a delicacy and are called ‘Huitlacoche’ or ‘Ambrosia of the Aztecs’, being canned and exported around the world, old galls however, are toxic. This smut has been present in southern Britain since around 1850 (Redfern, 2011).
Although I was interested to find this gall for the first time in Suffolk, it was with more mixed feelings that I recorded it for a second time on 5.x.2022 on my allotment in Kelsale (TM388644)!
References
Bowdrey, J. P. (2021). Three species of Cecidomyiidae new additions to the Suffolk Diptera Checklist. Trans. Suffolk Nat. Soc. 56: 14-1
Bowdrey, J. P. (2019). Andricus lucidus (Hartig, 1843) (Hymenoptera: Cynipidae) The Hedgehog Gall, new to Suffolk. Trans. Suffolk Nat. Soc. 55: 40-42.
Bowdrey, J. P. (2018). Plagiotrochus quercusilicis (Fabricius, 1798), a gall wasp (Hymenoptera: Cynipidae) new to Suffolk. Trans Suffolk Nat. Soc. 54: 29-31.
Jennings, M. T. & Bowdrey, J. P. (2022). Pediobius rotundatus (Fonscolombe, 1832) (Hymenoptera: Chalcoidea: Eulophidae) new to Britain with first reports of native parasitoids reared from Plagiotrochus quercusilicis (Fabricius 1798) (Hymenoptera: Cynipidae) in England. Entomologist’s Monthly Magazine 158: 201-206.
Redfern, M., Shirley, P. R. & Bloxham, M. (2011). British plant galls. 2nd ed. Field Studies Council.
Redfern, M. (2011). Plant galls. (New Naturalist No. 117) London, Collins.
Spooner, B. M. (2007). The gall mite Cecidophyopsis malpighianus in Britain. Cecidology 22(1): 42.
Jerry Bowdrey
10, Dennys Lane
Kelsale IP172PD
jeremybowdrey@btinternet.com