Asymmetrasca decedens (Paoli)
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Cicadellidae.
Common name:
Geographical distribution: The Mediterranean and Afrotropical regions, Central America and California.
Host plants: About 60 plant species in about 30 families.
Morphology: The body is 3.5-4.0 mm long, bearing whitish spots on the prodorsum and a pale band in the middle of the vertex. The aedeagus is asymmetric.
Life cycle: At 27ºC A. decedens completes a generation in about two weeks. It is active throughout the year, producing 4-5 annual generations. In citrus groves the pest often occurs in large numbers on the weed undergrowth, from which it moves onto the fruits, its numbers peaking in autumn and winter. On cotton the largest populations occur during mid- to late summer.
Economic importance: This species (sometimes retained in the genus Empoasca) attacks beans, beet, cotton, grapevine, lucerne, Prunus spp., potato and citrus. Its feeding affects leaves and causes severe growth reduction. Typical symptoms are leaves turning yellow (the so-called ‘hopperburn’) and curling their edges downwards, before wilting and dropping. In addition, this pest along with a number of other leafhoppers transmits different phytoplasma groups, which can be highly injurious. Feeding on maturing citrus fruit causes yellowish to brown scars, reducing market value. It may co-occur with other Hemiptera, compounding the damage.
Management: Chemical control measures are recommended in Turkey if an injury patch of 1 cm diameter per 250 fruits is seen. The pest shows much resistance to pesticides, but may be controlled with lime sulphur solutions. Eliminating the weed undergrowth also reduces pest numbers.
References
Atakan, E. 2009. Damage assessment of the leafhopper complex Asymmetrasca decedens (Paoli) and Empoasca decipiens Paoli] (Homoptera: Cicadellidae) in cotton. Journal of Pest Science 82: 227-234.
Baspinar, H., Uygun, N. and De Mendoza, A. H. 2011. Cicadellidae. In Vacante, V and Gerson, U. (Eds) Integrated Control of Citrus pests in the Mediterranean Region. Bentham E Books, pp. 119-125.
Freitas, N. and Aguin-Pombo, D. 2005. Distribution, food plants and control of Asymmetrasca decedens (Paoli, 1932) (Hemiptera: Cicadellidae). Boletim do Museu Municipal do Funchal 56 (315): 23–39.
Pastore, M., Raffone, E., Santonastaso, M., Priore, P., Paltrinieri, S., Bertaccini, A. and Simeone, A.M. 2003. Phytoplasma detection in Empoasca decedens and Empoasca spp. and their possible role as vectors of European Stone Fruit Yellows (16SrXB) Phytoplasma. Acta Horticulturae 657: 507-511.
Rigo, G. and Mori, N. 1997. Il contenimento delle populazioni di cicalina verde del pesco. Informatore Agrario Supplemento 53: 21-23.
Torres, J., Hermoso de Mendoza, A. and Jacas, J. 2002.Influencia de latemperatura y el fotoperiodo sobre el desarrollo de Asymmetrasca decedens (Paoli) (Homoptera: Cicadellidae). Boletín de Sanidad Vegetal Plagas 28: 263-272.