Tetranychus evansi Baker and Pritchard
Common name: Red tomato spider mite.
Taxonomic placing: Acari, Prostigmata, Tetranychoidea, Tetranychidae.
Geographical distribution: South America and the Caribbean, Sub-Sahara Africa, the Mediterranean region, South-East Asia and Australia.
Morphology: Female color orange to dark red, with indistinct dark blotches on each side of the body, and pale-orange legs, about 0.5 mm long. Dorsum with 13 pairs of setae, the hysterosomal striae are mostly longitudinal, forming a diamond-shaped pattern above legs III and IV. Male smaller, body yellow-orange, legs pale orange.
Host plants: Mostly Solanaceae, but also other cropa, like beans and cotton, and ornamentals like roses, as well as many weeds (Amaranthus, Chenopodium, Convolvus). A favorite host weed is Solanum nigrum L.
Life history: At 31°C 123 eggs/female were laid, but as many as 200 can be produced. The threshold of development was calculated to be at 10.3°C, and the shortest developmental time, less than one week, was at 36°C. The mites are usually on the lower sides of infested leaves, but their profuse webbings may cover entire plants. The mites can be dispersed by winds, irrigation water, and field workers (by adhering to clothing and tools), whereas long distance dissemination is by trade of host plants.
Economic importance: This is a major pest of solanaceous crops, especially tomato and eggplant in greenhouses, and is regarded as a very serious threat to such crops in Africa and the Mediterranean basin. In Africa the pest may reduce yields by up to 90%. Feeding punctures result in leaf wilting and drop and plants may die as a result of severe infestations. The mite’s rapid development and high fecundity lead to quick population growth, causing much economic damage.
Monitoring: The presence of solanaceous weeds, especially S. nigrum, covered by dense webbing, signals an infestation.
Horticultural methods: Pruning and trellising of tomatoes may result in better pest management, fewer fruit rots and diseases.
Plant resistance: The resistance of some tomato cultivars is due to the distribution and density of trichomes on its leaves.
Chemical control: Lime sulphur and neem based products and an enzyme inhibitor provide satisfactory control. Pesticides such as pyrethroids are losing their effectst; other synthetic acaricides had only limited success.
Biological control: The predator Phytoseiulus longipes Evans (Phytoseiidae), of South American origin, controls pest infestations within 4-5 weeks. Several other predators, such as Coccinellidae, Cecidomyiidae and Thysanoptera were also collected in pest colonies, but their effect is not clear. The entomopathogenic fungi Metarhizium anisopliae (Metschnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin attacked all mite stages; the extent of mortality from these infections was dependent on the host plant.
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Bonato, O. 1999. The effect of temperature on life history parameters of Tetranychus evansi (Acari: Tetranychidae). Experimental and Applied Acarology 23: 11–19.
Boubou, A., Migeon, A., Roderick, G.K and Navajas, M. 2011. Recent emergence and worldwide spread of the red tomato spider mite, Tetranychus evansi: genetic variation and multiple cryptic invasions. Recent emergence and multiple cryptic invasions of Tetranychus. Biological Invasions 13: 81-92.
EPPO Bulletin 2013. 43: 425–430, PM 7⁄116 (1) Tetranychus evansi.
Ferrero, M., Calvo, F.J., Atuahiva, T., Tixier, M.-S. and Kreiter, S. 2011. Biological control of Tetranychus evansi Baker & Pritchard and Tetranychus urticae Koch by Phytoseiulus longipes Evans in tomato greenhouses in Spain (Acari: Tetranychidae, Phytoseiidae). Biological Control 58: 30–35.
Nyoni, B.N. (qnd 6 co-authors) 2011. Pyrethroid resistance in the tomato red spider mite, Tetranychus evansi, is associated with mutation of the para‐type sodium channel. Pest Management Science 67: 891-897.
Onyambus, G.K., Maranga, R.O., Gitonga, L.M. and Knapp, M. 2011. Host plant resistance among tomato accessions to the spider mite Tetranychus evansi in Kenya. Experimental and Applied Acarology 54: 385–393.
Saunyama, I.G.M. and Knapp, M. 2003. The effects of pruning and trellising of tomatoes (Lycopersicon esculentum Mill.) on red spider mite (Tetranychus evansi Baker & Pritchard) incidence and crop yield in Zimbabwe. African Crop Science Journal 11: 269–277.
Soto, A., Venzon, M., Oliveira, R.M., Oliveira, H.G. and Pallini, A. 2010. Alternative control of Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) on tomato plants grown in greenhouses. Neotropical Entomology 39: 638‐644.
Wekesa, V.W., M. Knapp, M., Maniania, N.K. and Boga, H.I. 2006. Effects of Beauveria bassiana and Metarhizium anisopliae on mortality, fecundity and egg fertility of Tetranychus evansi. Journal of Applied Entomology 130: 155–159.
Wekesa, V.W., Vital, S., Silva, R.A., Ortega, E.M.M., Klingen, I. and Delalibera Jr., I. 2011.The effect of host plants on Tetranychus evansi, Tetranychus urticae (Acari: Tetranychidae) and on their fungal pathogen Neozygites floridana (Entomophthorales: Neozygitaceae). Journal of Invertebrate Pathology 107: 139–145.