Colomerus vitis

Colomerus vitis (Pagenstecher)

(The populations of this species may be mixed, especially in Egypt, with those of Colomerus oculivitis (Attiah)).

Taxonomic placing: Acari, Prostigmata, Eriophyoidea, Eriophyidae.

Common name: Grape erineum mite.

Host plants: Grapevines, Vitis vinifera.

Geographical distribution: Almost wherever grapes are grown.

Host plants: Grapevine (Vitis vinifera L.), including wild subspecies of Vitis.

Morphology: The body of the grape erineum mite is yellowish, about 0.18 mm in length, cylindrical, with a similar number (ca 70) of dorsal and ventral opisthosoma rings. The prodorsum bears a pair of forward-pointing setae and several weak, longitudinal ridges along its entire length. The featherclaw is five-rayed.

Life cycle: The mite lives on the lower side of grape leaves and in the buds, overwintering there and in bark crevices. Reproduction continues in winter, provided temperatures do not drop below 15°C. In the spring the mites move onto leaves as soon as they unfold and feed there, forming large colonies within the protective erineum. They may also be carried on the growing shoot from the bud, settling first in the basal buds, their numbers gradually diminishing in the more distant buds. Dispersal between plants is by winds, insects and especially by transferring propagation canes from infested stock to new areas. A life cycle is completed in about a fortnight, and 15-20 annual generations may be raised. Reproduction is by arrhenotoky; spermatophores are deposited by males on the leaves and taken up by the females.

Economic importance: This pest causes different forms of damage to the grape, believed to be due to different mite races. Feeding on the lower leaf surfaces induces the appearance of white-grey patches, made up of unicellular hairs (erineum) that grow out of depressions between the veins, and corresponding blisters that bulge out of the upper leaf sides. The patches later become brownish and may cover the entire leaf, leading to its premature drop. Such leaf damage is of economic importance only in nurseries, as it may retard plant growth. Another form of injury is due to feeding in the buds (each of which is a cluster of buds), resulting in deformations and stunting, and even death of buds. Finally, in heavy infestations the leaves curl, plant growth is retarded and yield is affected. Grape decline may continue for several years before the causative agent is discovered. Pest damage to various grape varieties depends on the type of buds carried on the canes. When only the primary bud can be fruitful, mite damage is far more severe than if the lateral buds are also capable of producing fertile shoots.

Management

Cultural control: Mite numbers can be considerably reduced by careful, strain-dependent pruning, which requires prior knowledge about the distribution of the pest in the various buds. In the first year pruning should leave the less infested buds (out of which the next season’s canes will grow), whereas second year pruning should then remove all canes that grow out of the more infested buds. Varieties whose buds are very tightly compressed can accommodate fewer mites and are therefore relatively undamaged by the pest.

Plant resistance: Varieties with higher levels of indol acetic acid (IAA) were found in Iran to be less affected by the mite than other varieties.

Chemical control: Acaricides in common usage applied in the spring (the only season when the pest is exposed), along with the pruning regime, may reduce injury. However, as damage is dependent on individual growth pattern, control decisions should individually be made for each variety, as well as according to the perceived damage - if any.

Biological control: Abroad C. vitis has several natural enemies of the families Phytoseiidae, Stigmaeidae and Tydeidae, but little is known about them in the Middle East.

References

Craemer, C. and Saccaggi, D.L. 2013. Frequent quarantine interception in South Africa of grapevine Colomerus species (Trombidiformis: Prostigmata: Eriophyidae): taxonomical and distributional ambiguities. International Journal of Acarology 39: 239-243.

Dennill, G.B. 1991. A pruning technique for saving vineyards severely infested by the grape bud mite Colomerus vitis (Pagenstecher) (Eriophyidae). Crop Protection 10: 310-314.

Dusso, C. and De Lillo, E. 1996. Grape. In: Eriophyoid Mites, Their Biology, Natural Enemies and Control (Ed. by Lindquist, E.E., Sabelis, M.W. and Bruin, J.), pp. 571-582. Elsevier, Amsterdam.

Harpaz, I. and Bernstein, Z. 1961. Occurrence of the bud mite strain of Eriophyes vitis (Pgst.) in the old world and the nature of its damage to grape vines. Proceedings XI Congress of Entomology 2: 47-48.

Khederi, S.J., Khanjani, M., Gholami, M. and De Lillo, E. 2018. Sources of resistance to the erineum strain of Colomerus vitis (Acari: Eriophyidae) in grapevine cultivars. Systematic and Applied Acarology 23: 405-425.

Ocete, R., del Tio, R. and Lara, M. 1995. Les parasites des populations de la vigne sylvestre, Vitis vinifera silvestris (Gmelin) Hegi des Pyrenees Atlantiques (France). Vitis 34: 191-192.

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