Aggiornamento dell’entomofauna fitofaga della douglasia in Italia

After its introduction in Italy, Douglas fir (Pseudotsuga menziesii) did not show damage due to phytophagous insects for several decades. Phytosanitary issues were recorded after the second world war, when attacks by sap sucking insects Gillettella coweni and G. cooleyi (native to North America like the Douglas fir) were first observed. The wide use of Douglas fir in Europe favored the adaptation of several native phytophagous insects to the new host. Furthermore, the removal of the undergrowth, as well as other trees to plant Douglas firs, favored the development of herbaceous species, thus affecting the dynamics of insect whose habitats include both the roots of herbaceous plants (immature stages) and the needles of coniferous trees. Moreover, the short distance from native conifer stands favor native insects to shift to the new host, especially xylophagous insects.