Two types of Norway spruce Picea abies (L.) H. Karst. infestation by the double spined bark beetle Ips duplicatus (C.R. Sahlb.) (Coleoptera: Scolytinae) in southern and north-eastern Poland

Przemysław Szmit

During an outbreak in the second half of the 1990s, the infestation pattern of I. duplicatus on standing trees in the Silesian Upland (southern Poland), was seen to be different from the pattern observed in the north-eastern spruce range. The "southern" type can be characterised by (i) the abundance of I. duplicatus galleries in lower parts of stems (including the basal parts of stems), and (ii) co-occurrence and high spatial competition with I. typographus. The "southern" type of infestation seems to be temporal in nature, related to the high abundance of I. duplicatus during the progradation and culmination phase of its outbreak.