Defoliators in native insect systems of the mediterranean basin

Native defoliating insects have been considered a threat to the forests since ancient time because of their periodic demographic explosions that have worried generations of forest managers and the public in general. Although trees generally recover from such defoliations in a relatively short time, both positive and negative consequences on growth and ecological functions of the forests have been documented. Damage by native defoliators is frequently inflicted whenever native tree species have been used for plantations, often outside of their natural range. Under such conditions the natural population regulation mechanisms, which are known to operate in pristine habitats, become less efficient or they simply need time before being established.We selected three major forest types to represent the importance and the role of native defoliators in the Mediterranean forests: pines, oaks, and poplars and willows. For each type we provide information about taxonomic traits, guild traits, economic damage, ecological impact, impact on humans, insect-plant interactions, insect-enemies interactions, outbreak dynamics, climate change, and management. Additional information for a few species typical of the Mediterranean forests is appended at the end of the chapter.