On the Sawfly Pristiphora subarctica (Forsslund, 1936) (Hymenoptera: Tenthredinidae) in Spruce Plantations of the Southern Alps

Pristiphora subarctica is commonly considered a rare sawfly species feeding on Norway spruce (Picea abies (L.) Karsten) with central and northern European distribution. In this paper the occurrence of a large population of this sawfly species in spruce plantations of the Southern Alps (Asiago Plateau, Venetian Prealps, Italy) is documented. Three plantations were attacked for two subsequent years starting from spring 1998. Although no trees died as a consequence of the defoliation, the crown architecture was compromised by the growth of multiple shoots derived from proventitious buds. Th e population density of verwintering stages of the sawfly was estimated by searching for cocoons in soil samples and density of adults was monitored with yellow sticky traps. The damage to the plantations was evaluated by counting the number of trees bearing red defoliated leaders.