Aleurotrachelus trachoides (Hemiptera: Aleyrodidae): addition to the EPPO Alert List
Why: Aleurotrachelus trachoides (Hemiptera: Aleyrodidae) was identified in the EPPO study on pest risks associated with the import of tomato fruit as possibly presenting a risk for the EPPO region. This whitefly species was later selected as a priority for PRA by the EPPO Panel on Phytosanitary measures. An EPPO Expert Working Group will meet in December 2015 to conduct PRAs on several tomato pests, including A. trachoides.
Where: A. trachoides is native from the Neotropical region; it has spread to the Pacific, and there are recent findings in Africa.
EPPO region: absent
Africa: Gambia (unconfirmed), Mozambique, Nigeria, Reunion.
North America: Mexico, USA (California, Florida, Hawaii, Louisiana, Texas).
Central America and Caribbean: Antigua and Barbuda, Bahamas, Barbados, Belize, Cayman Islands, Costa Rica, Cuba, Dominica, Dominican Republic, El Salvador, Guadeloupe, Guatemala, Haiti, Honduras, Jamaica, Martinique, Netherlands Antilles (Curaçao), Nicaragua, Panama, Puerto Rico, Trinidad and Tobago, Virgin Islands (US).
South America: Brazil (Bahia, Rio do Janeiro), Colombia, Ecuador (Galapagos), French Guiana, Guyana, Peru, Suriname, Venezuela.
Oceania: Fiji, French Polynesia (Rangiroa, Tahiti), Guam, Micronesia (Kosrae island). There are also unconfirmed reports from Nauru and Tonga.
On which plants: A. trachoides is a polyphagous species with a preference for Solanaceae and Convolvulaceae. Solanaceous hosts include major cultivated species such as Capsicum spp., Solanum lycopersicum (tomato), S. melongena (aubergine), Nicotiana tabacum (tobacco), ornamentals (Cestrum, S. pseudocapsicum, S. seaforthianum) and wild plants/weeds (Datura stramonium, S. nigrum). The pest seems to be attacking mainly Capsicum spp., and to a lesser extent S. melongena and S. lycopersicum. The importance of host plants belonging to other families is not clear, but A. trachoides has been reported on cultivated plants such as, Annona spp., Citrus limon (lemon), Colocasia esculenta (taro), Ipomoea batatas (sweet potato), Persea americana (avocado), Psidium guajava (guava), Theobroma cacao (cocoa), and Rosa.
Damage: A. trachoides mostly feed on leaves and young shoots, but fruit can also be attacked. Direct damage is caused by larvae and adults feeding on large quantities of sap. Symptoms may include plant stunting, and for fruiting species, a lower fruit production (i.e. smaller number of fruits with incomplete development). Indirect damage is caused by sooty moulds developing on honeydew secreted by the insect. This may reduce photosynthesis, as well as the aesthetic and economic value of the plants. A. trachoides is not known to be a virus vector.
Adults are 1-2 mm long and a large part of their body is covered with white waxy secretions. Nymphs are black and partly covered by thick cottony white filaments. Females lay eggs on the lower surface of young leaves. Eggs are initially white or yellowish, becoming grey to brown. They are oblong and glued to the leaf by a short peduncle. First stage larvae are flat and round, and usually stay on the leaf on which they were laid. The second to fourth larval stages, as well as puparia also develop on the leaves. Adults can fly over short distances (especially when they are disturbed) but they are also readily transported by the wind or on clothes. No details could be found on the duration of life cycle, temperature and humidity requirements of A. trachoides.
Dissemination: over short distances, actively flying or wind-carried adults can disseminate the species. Over longer distances, trade of infested plants can spread all stages of the pest. A. trachoides has been intercepted by several countries (e.g. United Kingdom, USA) on different types of leafy vegetables and ornamentals.
Pathway: plants for planting, fruits and vegetables (including leaves), cut flowers of host plants from countries where A. trachoides occurs.
Possible risks: solanaceous crops such as capsicum, aubergines and tomatoes are widely grown in the EPPO region. The climatic similarity according to the ‘EPPO study on pest risks associated with the import of tomato fruit’ between the area where A. trachoides occurs and the EPPO region is low to medium (A. trachoides is a Nearctic species), but the pest might find suitable conditions under glasshouse conditions. Control of whiteflies can be difficult in both outdoor and protected crops. In the literature, several Encarsia species (e.g. Encarsia cubensis, E. formosa, E. hispida, E. nigricephala, E. pergandiella, E. tabacivora) are reported to parasitize A. trachoides, but there is no data about their potential use as biocontrol agents in practice. Although data is generally lacking about the economic impact of A. trachoides, it seems desirable to avoid the introduction of another whitefly species in the EPPO region which might disrupt the existing IPM strategies that are already in place.
EPPO RS 2015/208
Panel review date - Entry date 2015-11
Sources
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INTERNET
- Charles Darwin Foundation. Galapagos species checklist. http://checklists.datazone.darwinfoundation.org/introduced-species/introducedinvertebrates/aleurotrachelus-trachoides-back-1912/
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