Aceria fraxinivorus
| Aceria fraxinivorus | |
|---|---|
 | |
| The ash key gall and unaffected ash keys. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Subclass: | Acari |
| Order: | Prostigmata |
| Family: | Eriophyidae |
| Genus: | Aceria |
| Species: | A. fraxinivorus |
| Binomial name | |
| Aceria fraxinivorus Nalepa, 1909[1] | |
| Synonyms | |
|
Eriophyes fraxinivorus; Phytoptus fraxini;[2] Aceria fraxinivora.[3][4] | |
Aceria fraxinivorus, the cauliflower gall mite,[5] causes the ash key gall that is found on the inflorecences commonly called the flowers or seeds.[6] The hanging seeds are the "keys" of the common ash tree (Fraxinus excelsior).[7]
Appearance and cause
The gall presents usually as a sizable irregular deformity formed from fused and swollen flower stalks (pedicels),[8] however it has also been found on buds, leaf stalks, twigs or trunks.[9] It is brown when fully formed, finally black, but green at first.[1] Once the leaves have fallen, the galls, filled with mites, are very obvious within the trees branches and may remain for a year or more.[5] 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.[8]
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.[5]
Distribution
The 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.[5]
Inquilines
Other acarine gall-mites, aphids, psyllids, and midges are often found within the galls.[8]
Effects
Almost every inflorescence may be involved, the reproductive capacity therefore being reduced, however some seeds may still develop normally amongst the galls.[8]
Notes
References
- 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 (2002). British Plant Galls. Identification of Galls on Plants and Fungi. Shrewsbury: FSC Publications. ISBN 1-85153-214-5.
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