I lepidotteri defogliatori in ambiente forestale: il caso studio della processionaria del pino

Some moths are known as important indicators of the quality of the environment, and therefore used within surveys about the biodiversity conservation. However, some other lepidopteran species are known to deeply threaten the agricultural and forest environment, as well as other human activities, representing a serious public health hazard. This aspect causes several problems, often not easily solved. Only a limited number of species can be considered harmful, not because of their feeding activity, but mainly for the occurrence of remarkable outbreaks. Among these insects, the noteworthy species in the forest environment are Euproctis chrysorrhoea L., Lymantria dispar (L.), Thaumetopoea processionea (L.), Tortrix viridana (L.) and Zeiraphera diniana (Hübner). Their control, which rarely threaten the surviving of the wood, is normally regulated by natural factors. A control plan may be necessary only in urban areas, or if the outbreak of the urticant caterpillars endangers the public health. This issue drew the attention on another forest pest, the pine processionary moth Thaumetopoea pityocampa (Denis et Schiffermüller). This lepidopteran species is widely spread, from the Mediterranean area to the center of France. The effects of the climate change have led to its establishment in new areas, at broader latitudes and altitudes, and to its adaptation to a new host, the mountain pine Pinus mugo Turra, in addition to the common hosts black and Scots pine. The population of this insect shows characteristic outbreaks, whose length spans from one to three years, interrupted by long breaks, from 5 to 8 years. During these outbreaks, besides the severe consequence due to the defoliation of the host trees, the ecological and sanitary problems give rise to concern, since the larvae are covered with urticating hairs, harmful to humans, and animals too. This is particularly worrying when the host plants are located in the urban environment. In Italy, the control of the pine processionary moth is compulsory, following a Ministerial Decree dated 1926; for this reason it is necessary to set effective plans to prevent and control the infestations, both in the short and in the long term.