Georgofili World

Newsletter of the Georgofili Academy

The impact of introduced exotic insect plant pests on Italian urban forest trees

More than 500 insect pests in the Italian ecosystems are considered to be exotic (DISIE, 2008). About 200 of these species have been introduced and have established themselves in Italy since 1970. The intensification of plant trade between Italy and geographically distant commercial partners is considered to be one of the main causes of these introductions. Climatic abnormalities have also favored the spread and acclimation of these exotic organisms. Climatic change influences directly the establishment of poikilothermic insects by favoring the survival of a great number of introduced individuals or indirectly through the alterations induced in host phenology. 
Urban forest trees particularly affected by these exotic insects in northern and central Italy include alder, beech, birch, hornbeam, maple and sycamore trees. These landscape trees have been severely damaged by Cerambicydae Anoplophora chinensis Forster and A. glabripennis (Motshulsky). 
The devastating impact of the introduction of the curculionid Rhynchophorus ferrugineus (Olivier) on landscape palms is well known. Canary palms [Phoenix canariensis (Hortorum ex Chabaud)] are one of the preferred hosts of this insect, native to Asia. From 2004 to 2009, more than 30,000 Canary palms have been killed by this insect in Abruzzo, Apulia, Campania, Latium, Liguria, Marches, Sardinia and Sicily.
Other introduced species such as the Metcalfa pruinosa (Say) (Rhynchota Flatidae), Corytuca ciliata (Say) and C. arcuata (Say) (Rhynchota Tingidae), Phenacoccus madeirensis Green (Rhynchota Pseudococcidae), Ceroplastes japonicus Green and Protopulvinaria piriformis (Cock.) (Rhynchota Coccidae), Cameraria ohridella Descka & Dimic (Lepidoptera Gracillariidae), Paysandisia archon (Burmeister) (Lepidoptera Castniidae), Megaplatypus mutatus (Chapuis) (Coleoptera Platypodidae), Xylosandrus crassiusculus (Motschulsky) and X. germanus (Blandford) (Coleoptera Scolytidae), Callidiellum rufipenne (Motschulsky), Phoracanta semipunctata Fabricius, and P. recurva Newmann (Coleoptera Cerambycidae) are severely damaging ornamental trees in localized areas. The introductions of these exotic forest insect pests into Italian forests can be prevented by implementing rigorous coordinated surveys by the member countries and inspections at the port of entry to each country in the organization. By setting up monitoring networks to promptly detect the introduction and by delimiting the areas affected by these newly introduced pests, it is possible to contain the infestations in Italian forest ecosystems.
Once new exotic insect pests are introduced, integrated management including appropriate forestry management practices, biological control methods and trapping are recommended, whenever applicable, to limit the devastating effects induced by these harmful exotic forest insects.


Santi Longo - longosan@unict.it



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