Introduction of Tetranychus evansi in some Mediterranean countries: Addition to the EPPO Alert List
A new species of spider mite, Tetranychus evansi, has recently been found in several Mediterranean countries. This species of South American origin has accidentally been introduced to other parts of the world, and is reported as a serious pest of cultivated Solanaceae. Considering its invasive behaviour and the severity of damage, it was felt useful to add it to the EPPO Alert List.
Tetranychus evansi (Acari: Tetranychidae) – red spider mite
Why: The EPPO Secretariat was informed by Dr Reynaud (FR) that a new spider mite species, Tetranychus evansi was spreading within Mediterranean countries. As it is considered as an invasive species and a damaging pest of tomatoes and other solanaceous crops, it was felt useful to add it to the EPPO Alert List.
Where: T. evansi is of South American origin and has been accidentally introduced into other parts of the world (e.g. in the 1980s in Southern Africa, at the end of 1980s- early1990s in north Africa, 1995 in Spain, 2000 in Portugal).
EPPO region: Morocco, Spain (along the Mediterranean coast from Valencia to Almería, also found on protected crops in Tenerife), Portugal, Tunisia.
Africa: Democratic Republic of Congo, Kenya, Malawi, Mauritius (including Rodrigues island), Mozambique, Namibia, Réunion, Seychelles, Somalia, South Africa, Zambia, Zimbabwe.
South America: Brazil, Puerto Rico.
North America: USA (Arizona, California, Florida, Texas).
On which plants: T. evansi tends to prefer solanaceous crops: tomato (Lycopersicon esculentum), aubergine (Solanum melongena), potato (S. tuberosum), tobacco (Nicotiana tabacum). But it is also found from several other vegetable (e.g. beans, citrus, cotton, castor bean) and ornamental crops (e.g. Rosa), as well as on many weed species (e.g. Amaranthus, Chenopodium, Convolvus, Conyza, Diplotaxis, Hordeum murinum, Lavatera, Sonchus, Solanum nigrum).
Damage: Damage is similar to other spider mites. Feeding punctures led to whitening or yellowing of leaves, followed by desiccation, and eventually defoliation. In case of severe attacks, plants may die. Mites and their webbing can be seen on the underside of the leaf. Adult females are 0.5 mm long, oval, orange red with and indistinct dark blotch on each side of the body. They can lay up to 200 eggs. Males are smaller and straw to orange coloured. At 25°C, the life cycle is completed in 13.5 days. Development is favoured by hot dry conditions (minimum temperature 10°C, optimum temperature 34°C). In Southern Africa, it is considered as the most important dry season pest of tomatoes. In Zimbabwe, up to 90% yield losses have been recorded from field trials.
Dissemination: Over short distances, mites can be spread by wind, irrigation water, and field workers (clothing, tools). Trade of host plants can ensure long distance dissemination. The small size of T. evansi, and its morphological similarity with other spider mite species renders its detection difficult on consignments.
Pathway: Plants for planting of Solanaceae, fruits (?)
Possible risks: Solanaceae are important crops in the EPPO region both outdoor and under protected cultivation. In many countries where T. evansi has been introduced, it is reported as a serious pest (in particular on tomato) which may displace the already existing spider mite species. T. evansi is morphologically similar to other spider mite species already present in Europe (e.g. T. urticae), it can easily be confused with them and therefore remain undetected. Unlike other spider mite species, biological control with predatory mites such as Phytoseiulus persimilis and Neoseiulus californicus is not effective. Chemical control is possible, but data is lacking on the ability of T. evansi to develop resistance.
EPPO RS 2004/080
Panel review date - Entry date 2004-05
Personal communication with Dr P. Raynaud (2004-01), Laboratoire National de la Protection des Végétaux, Unité d’entomologie, Montpellier, FR.
Bolland, H.R.; Vala, F. (2000) First record of the spider mite Tetranychus evansi (Acari: Tetranychidae) from Portugal. Entomologische Berichten, 60(9), p 180.
Ferragut, F.; Escudero, L.A. (1999) Tetranychus evansi Baker & Pritchard (Acari, Tetranychidae), una nueva araña roja en los cultivos hortícolas españoles. Boletín de Sanidad Vegetal - Plagas, 25(2), 157-164.
Ferragut, F.; Escudero, L.A. (2002) La araña roja del tomate Tetranychus evansi (Acari, Tetranychidae) en España: distribución, biología y control. Phytoma España, no. 135, 111-113.
Denmark H.A. (1973) Tetranychus evansi Baker and Pritchard (Acarina: Tetranychidae) in Florida. Entomology Circular no. 134. Florida Department of Agriculture and Consumer Services. Division of Plant Industry, 2 pp.
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