EPPO Alert List – Tetranychus mexicanus (Acari: Tetranychidae)
Why
In October 2018, Tetranychus mexicanus (Acari: Tetranychidae) was found for the first time in the Netherlands in a greenhouse on pot plants of Beaucarnea recurvata (EPPO RS 2018/223). In October 2019, this outbreak was officially declared eradicated. Considering that this spider mite is polyphagous and could be a risk for glasshouse crops in the EPPO region as well as outdoor crops in the Southern EPPO region, the Panel on Phytosanitary Measures suggested that T. mexicanus should be added to the EPPO Alert List.
Where
T. mexicanus has a neotropical distribution. It is reported from the Americas. A record in China in 1994 has not been confirmed.
EPPO Region: absent (an outbreak was detected in 2018 in the Netherlands but was subsequently eradicated).
North America: Mexico, USA (Florida, Texas).
Central America and the Caribbean: Costa Rica, Cuba, El Salvador, Guadeloupe, Honduras, Martinique, Nicaragua.
South America: Argentina, Brazil (Acre, Amapa, Amazonas, Bahia, Ceara, Distrito Federal, Goias, Maranhao, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Para, Paraiba, Pernambuco, Rio de Janeiro, Rio Grande do Sul, Santa Catarina, Sao Paulo, Sao Paulo, Sergipe), Colombia, Paraguay, Peru, Uruguay, Venezuela.
On which plants
About 100 species, belonging to 44 plant families, have been recorded as hosts (Migeon & Dorkeld, 2018). The finding on Beaucarnea recurvata in the Netherlands adds a new plant family (Asparagaceae). The host range includes important crops in the EPPO region such as Citrus spp., Malus domestica, Vitis vinifera, as well as many plants used as ornamentals.
Damage
Damage is similar to other spider mites. Feeding punctures lead to whitening or yellowing of leaves, followed by desiccation, and eventually defoliation. Mites and their webbing can be seen on the underside of the leaf. Females are carmine in colour and bigger than males. The life cycle at 27°C is about 10-12 days. In its current area of distribution, T. mexicanus has been recorded as causing economic damage on soursop (Annona muricata), passion fruit (Passiflora edulis), cocoa (Theobroma cacao). In southern Brazil, the following symptoms were observed on Citrus: chlorotic spots on the leaves, shoots' death, as well as leaf and fruit fall. Bleaching of leaves of ornamental plants may affect their commercial value.
Dissemination
Over short distances, Tetranychus mites are mainly transported with their webs by wind. Trade of host plants can ensure long distance dissemination.
Pathways
Plants for planting, cut foliage? fruits with green parts?
Possible risks
Although T. mexicanus mainly has a neotropical distribution, it could potentially establish in the Southern part of the EPPO region, as well as become a glasshouse pest in the entire EPPO region. Establishment in the EPPO region may affect export to certain regions in the world as it is a quarantine pest in several countries (e.g. Taiwan and Japan).
Sources
Anonymous (1980) A tetranychid mite (Tetranychus mexicanus (McGregor)) - Florida - new United States record. Cooperative Plant Pest Report 5(1), p 11.
Beer RE, Lang DS (1958) The Tetranychidae of Mexico. University of Kansas Science Bulletin 38,
Cheng LS (1994) A new record of Chinese Tetranychidae [in Chinese]. Zoological Research 15, p 20.
de Sousa JM, Gondim MGC, Lofego AC, de Moraes SJ (2010) Biology of Tetranychus mexicanus (McGregor) (Acari: Tetranychidae) on three species of Annonaceae. Neotropical Entomology 39(3), 319-323.
INTERNET
DefesaVegetal.Net. Tetranychus mexicanus. http://www.defesavegetal.net/tetrme
Migeon A, Dorkeld F (2019). Spider Mites Web. A comprehensive database for the Tetranychidae. https://www1.montpellier.inra.fr/CBGP/spmweb/ [accessed March 2022]
Ministry of Agriculture Nature and Food Quality. Netherlands Food and Consumer Product Safety Authority.
- First outbreak of Tetranychus mexicanus (spider mite) on ornamental plants of Beaucarnea recurvata in a professional greenhouse.
- Eradication confirmed of the first outbreak of Tetranychus mexicanus (spider mite) on ornamental plants of Beaucarnea recurvata in a professional greenhouse.
NVWA (2018) Quick scan number: QS-ENT-2018-007. Tetranychus mexicanus. https://english.nvwa.nl/topics/pest-risk-analysis/documents/plant/plant-health/pest-risk-analysis/documents/pest-risk-analysis-tetranychus-mexicanus-quick-scan
Vacante V (2010) Citrus mites: identification, bionomy and control. CABI Publishing: Wallingford. 378 pp.
EPPO RS
Entry date: 2019-09,