Taxonomy

Parasyrphus annulatus

Distribution

Species Biology

Preferred environment

Forest; various types of coniferous forest up to the level (inclusively) of Larix forest, plus conifer plantations and, occasionally, acidophilous Quercus forest. The few Irish records are from the vicinity of Picea plantations, but there is no obvious reason why a spruce-associated hoverfly should be so rarely recorded from spruce plantations in Ireland, if it occurs here in such situations at all. Possibly, the aphids upon which the larvae of P. annulatus feed are themselves scarce in Irish conifer plantations. Or, possibly, the species has only recently arrived in Ireland and its spread is for some reason less rapid than that of some of the other conifer-associated species? Certainly, none of the other Parasyrphus species associated only (or almost entirely) with conifers, and now found in Ireland, are frequent here. Neither were any of them recorded from Ireland prior to the 1970s. But the presence of P. annulatus in Ireland was recognised in the 1950s (Coe, 1953). Since P. annulatus is known from taiga forest in northern Norway south to pine forest in the Alpes Maritimes of southern France, plus right across Siberia to the Pacific coast, it does not seem likely that climatic factors would restrict its occurrence in Ireland.

Adult habitat & habits

To a significant extent arboreal, but descending to visit flowers.

Flight period

May/beginning August, with occasional specimens on into September. Larva: not described, but reported by Bartsch et al (2009a) as found feeding on aphids on Abies spp. Curiously, Kula (1982) records larvae of P. annulatus as hibernating in the leaf litter of spruce (Picea) forest, though he reports no records of the larvae of this species among syrphid larvae collected from spruce foliage, which he investigated in another part of this same study. Bastian (1986) also records larvae from Picea.

Flowers visited

White umbellifers; Allium, Caltha, Cardamine, Euphorbia, Galium, Inula, Ligustrum, Meum, Prunus spinosa,Pyrus communis, Ranunculus, Rubus idaeus, Sambucus nigra, Sorbus aucuparia, Viburnum opulus.

Irish reference specimens

In the collections of NMI

Determination

See Key provided in StN Keys volume. The male terminalia are figured by Hippa (1968b). The adult insect is illustrated in colour by Kormann (1988), Stubbs and Falk (1983) and Torp (1994).

Distribution

World distribution(GBIF)

From northern Fennoscandia south to southern France (Alpes Maritimes); from Ireland eastwards through northern and central Europe (and mountainous parts of Italy and the former Yugoslavia) into European parts of Russia and on to the Caucasus; through Siberia to the Pacific coast (Kuril Isles). 

Irish distribution

Recorded as occurring in Ireland in Coe (1953). Considered simply on the basis of the small number (four) of records there are of this species from Ireland, it should be regarded as threatened here. It has a wide range elsewhere in Europe, and is not generally regarded as threatened, though it would be categorised as under threat in the Netherlands. The fact that apparently appropriate habitat is becoming increasingly available year by year, in the form of conifer plantations, should lead to increased frequency of P. annulatus in Ireland. However, there is no evidence that the species is responding in this way - unknown factors appear to be limiting its frequency in Ireland. One possibility which requires to be brought into consideration is that P. annulatus is not associated with conifers in Ireland, but with deciduous trees. A few conifer-associated beetles, notably the clerid Thanasimus formicarius (L.) and the lycid Pyropterus nigroruber (DeGeer), are presumed to have survived the prolonged absence of indigenous conifers in Ireland via a limited association with deciduous trees, which has left them apparently adapted to this situation and unable to take advantage of the recent re-appearance of conifers mediated by human activity. It is conceivable that some similar history is responsible for the curious situation of P. annulatus in Ireland. But if other conifer-associated syrphids (e.g. Parasyrphus lineolaP. malinellus) are arguably recent arrivals in Ireland, which have established themselves since conifer plantations were introduced to the landscape, why would P. annulatus be unable to do likewise? If P. annulatus were able to colonise Irish conifer plantations by immigration from elsewhere, any localised indigenous P. annulatus population associated with deciduous trees would be unlikely to figure prominently in distribution records, its presence being masked by records of immigrants to the conifers. The relative scarcity of Irish records of various conifer-associated hoverflies is alluded to a number of times in these species accounts, the most extreme examples being Didea alneti and M. compositarum. There is perhaps a general conclusion to be drawn from these data, namely that, although the conifer plantations scattered around the Irish countryside in ever-increasing quantity might appear to provide habitat for syrphids with larvae feeding on aphids in conifer foliage, so that the conifer foliage-associated syrphids in the Irish fauna should be reasonably frequent, if not increasing in frequency, this interpretation fails to take into account the significance of other factors which may limit occurrence of these insects. Returning to the case of P. annulatus in Ireland, there does not seem to be any obvious explanation for the scarcity of Irish records of this species. So, to err on the side of caution, the species should be included in any listing of insects requiring protection in the island.

Temporal change

Records submitted to Data Centre in 2024

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References

Publications

Speight, M. C. D. (2008) Database of Irish Syrphidae (Diptera). Irish Wildlife Manuals, No. 36. National Parks and Wildlife Service. Department of Environment, Heritage and Local Government, Dublin, Ireland.

Speight, M.C.D. (2014) Species accounts of European Syrphidae (Diptera), 2014. Syrph the Net, the database of European Syrphidae, vol. 78, 321 pp., Syrph the Net publications, Dublin.

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