Aceria fraxinivora, also known as the cauliflower gall mite and the ash key gall, causes the growths, known as galls, found on the hanging seeds or "keys" of the ash (Fraxinus) species.[4]
| Aceria fraxinivora | |
|---|---|
| |
| The ash key gall and unaffected ash keys | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Family: | Eriophyidae |
| Genus: | Aceria |
| Species: | A. fraxinivora
|
| Binomial name | |
| Aceria fraxinivora | |
| Synonyms | |
|
Eriophyes fraxinivorus | |
Appearance and cause
editThe mite usually attacks the flower clusters soon after they open. The individual gall is no more than 2 cm across but when grouped together can be impressive as they present a sizable irregular deformity formed from the fused and swollen flower stalks (pedicels).[5] The gall has also been found on buds, leaf stalks, twigs or trunks. It is brown when fully formed, finally black, but green at first. Once the leaves have fallen, the galls, filled with mites, are obvious and may remain for a year or more. Leaflets or entire leaves and petioles may also be involved, with additional distortions such as thickening and leaf lamina rolling, especially when the tree is heavily infested.[1][2][4] Almost every inflorescence may be involved, the reproductive capacity therefore being reduced, however some seeds may still develop normally amongst the galls.[2]
The cause of the gall are mites, mainly female, the eggs being viable without fertilization. These gall-mites are specialist species; they are cylindrical and feed on sap, and have no circulation or respiratory systems, only two pairs of legs and no eyes.[4]
Species of ash galled, include white ash or American ash (Fraxinus americana), narrow-leafed ash (Fraxinus angustifolia & subsp. oxycarpa), Bunge's ash (Fraxinus bungeana), common ash (Fraxinus excelsior), manna ash (Fraxinus ornus), green ash or red ash (Fraxinus pennsylvanica).[6]
Distribution
editThe ash key gall is widespread in Britain; its numbers vary with the changes in annual seed production levels.[1] In France and the Netherlands they are known as cauliflower galls.[4]
Other acarine gall-mites, aphids, psyllids, and midges are often found within the galls, including the larvae of the gall midge Arthrocnodax fraxinellus which predates the mites of Aceria fraxinivora.[2][6]
References
edit- ^ a b c Redfern, Margaret; Shirley, Peter; Bloxham, Michael (2011). British Plant Galls (Second ed.). Preston Montford: FSC Publications. pp. 117 & 425. ISBN 978-1-85153-284-1.
- ^ a b c d Darlington, Arnold (1975). Plant Galls in Colour. Poole: Blandford Press. pp. 171–2. ISBN 0-7137-0748-8.
- ^ "Aceria Galls On Ash". National Biodiversity Network. Retrieved 25 July 2017.
- ^ a b c d "Cauliflower Gall Mite - Aceria fraxinivora". Nature Spot. Retrieved 25 July 2017.
- ^ Chinery, Michael (2011). Britain's Plant Gall. Old Basing, Hampshire: WILDGuides Ltd. p. 33. ISBN 978-190365743-0.
- ^ a b Ellis, W N. "Aceria fraxinivora (Nalepa, 1909)". Plant Parasites of Europe. Retrieved 25 January 2021.
Further reading
edit- Darlington, Arnold (1975). Plant Galls in Colour. Poole: Blandford Press. ISBN 0-7137-0748-8.
- Hancy, Rex (2000). The Study of Plant Galls in Norfolk. Norfolk & Norwich Naturalists' Society.
- Redfern, Margaret & Shirley, Peter (2011). British Plant Galls. Identification of Galls on Plants and Fungi. Shrewsbury: FSC Publications. ISBN 978 1 85153 284 1.