Distribution and Ecology of Lymantria-monacha L and Cephalcia Spp In Nonoutbreak Areas of Trentino (n-italy)

The life history and the ecology of Lymantria monacha and Cephalcia spp. were studied in spruce (Picea abies) stands under latent conditions. Methods were based on the use of different monitoring devices, whose efficiency was evaluated. The abundance of L. monacha monitored by pheromone traps, was inversely proportional to the altitude and the catches fell always within the range known for the latent populations. The following species of sawflies of the genus Cephalcia were found, in order of decreasing abundance: C. arvensis, C.fallenii, C. abietis, C. alashanica. They presented different flight period, C.fallenii being the first emerging species in spring, followed by C. arvensis, C. abietis, C. alashanica and C. arvensis again. The problem of the peaks in the flight of C. arvensis is discussed in the light of the recent findings in Czechoslovakia. The devices used in monitoring (tree band, yellow board, emergence trap) supplied different results for the sex ratio and the level of catches. Evidence for attraction between individuals is given. The catches of the most abundant species were strongly influenced by the altitude and the stand characteristics. L. monacha seems to prefer the lower sites, with a large number of small trees. C. arvensis and C.fallenii were most abundant in the colder sites, characterized by a medium (C. arvensis) or a medium-high (C.fallenii) diameter and by a low number of trees. The results are compared with the stand characteristics of the outbreak areas.