Seminar: Linda Lehmanski

Past decades have been marked by rising tree mortality triggered by more frequent extreme weather events like drought, heat or storms. Such events can also lead to an increased susceptibility of trees towards biotic agents like bark beetles. Despite a rich body of research, reaching back more than 250 years, major knowledge gaps concerning ecological interactions like host tree selection still remain. In early spring, overwintering pioneer beetles start swarming to search for new potential breeding sites and being exhausted from hibernation and food deprivation, they can often find suitable hosts in stressed and weak spruce trees that offer less defence against attackers. Because seasonal population growth depends on the success of the pioneer beetles, such a targeted host selection is of high ecological relevance. In our study we assumed that bark beetles (Ips typographus) use olfactory signals emitted by spruce trees (Picea abies) for identifying and localizing suitable hosts. We measured volatile organic compounds emitted from stems in trees that were weakened and damaged by windthrow and compared volatile emission profiles with those from vital trees.