Metcalfa pruinosa: a new pest in Europe
Metcalfa pruinosa (Homoptera: Flatidae) originates from the New World. It is present from Canada (Quebec) to Brazil, and in some islands of the Caribbean. In Europe, it was first found in Italy (1979) around Trevise (Veneto), and then spread in the North-East of Italy (Piemonte-Val d'Aosta, Lombardia, Friuli-Venezia-Giulia, Emilia-Romagna, Toscana). The pest has been found in the south-east of France (region of Provence-Alpes-Côte d'Azur), around 1986. In Switzerland, it was reported for the first time in 1993 in the south of Tessin. The pest is also reported as present in Slovenia.
Adults are 7-9 mm long, dark-brown covered with whitish waxy secretions. Larvae are white and also covered by waxy secretions. There is one generation per year. Eggs are laid in September in bark crevices of many woody plant species and the insect overwinters in this form. The first larvae hatch in May-June and five larval instar are observed. The first adults appear in summer (July). Larvae are generally found at the under side of the leaves, and adults are aligned on the twigs in a rather characteristic way. Larvae and adults feed on sap and produce high amounts of honeydew on which sooty mould will develop. However, the honeydew can be used by honey-making insects. At present, M. pruinosa has not been recorded as a vector of viruses or phytoplasmas.
M. pruinosa is an extremely polyphagous insect which can attack fruit trees, forest trees, ornamentals and weeds. In Italy, 173 host plants have been recorded, the most attractive seem to be grapevine, fig tree and wild Rubus. Damage have been reported on grapevine, apple, pear, citrus, olive, citrus, apricot, walnut, plum, sunflower, soybean and persimmon. However, at present this pest does not appear as very damaging, although it may cause problems in nurseries. In addition, chemicals do not seem very efficient as this insect is covered with waxy secretions and little is known about its potential natural enemies. It is suggested that M. pruinosa can be transported over long distances on vehicles as infestations have been observed along the roads. Local invasion of the surroundings is then ensured by natural spread.
Sources
Anonymous (1995) Phyto Régions...Provence-Alpes-Côte d'Azur. Une mineuse et Metcalfa.
Phytoma - La Défense des Végétaux, n° 475, p 3.
Bilancio Fitosanitario (1995) Informatore Fitopatologico No. 2, 6-33.
Bilancio Fitosanitario (1995) Informatore Fitopatologico No. 3, 8-37.
Jermini, M.; Bonavia, M.; Brunetti, R.; Mauri, G.; Cavalli, V. (1995) Metcalfa pruinosa Say, Hyphantria cunea (Drury) et Dichelomyia oenophila Haimah., trois curiosités entomologiques ou trois nouveaux problèmes phytosanitaires pour le Tessin et la Suisse ?
Revue Suisse de Viticulture, Arboriculture, Horticulture 27 (21), 57-63.
Della Giustina, W.; Navarro, E. (1993) Metcalfa pruinosa, un nouvel envahisseur ?
Phytoma - La Défense des Végétaux, n° 451, 30-32.