Ecological segregation of bark beetle (Coleoptera, Curculionidae, Scolytinae) infested Scots pine

Bark beetles infest several pine tree species, often creating major economic losses. Biotic interactions between Scolytinae populations inhabiting Pinus sylvestris were analyzed using a new sampling method involving a two dimensional division of tree space resources into units and sections. The goal was to evaluate the effects of the type of available reproduction material on insect infestation. The P. sylvestris stands in this study included an analysis of bark beetles colonizing dead trees and uninfested living trees (trap trees). Analyzed trees were harvested and their stems divided into ten equal units; each unit was halved into two sections (half of the stem circumference). The colonization of dead trees by insects was evaluated immediately after cutting for infested trees and 2 months after cutting for trap trees. The type of breeding material significantly affected the species composition of bark beetles infesting P. sylvestris. The dead trees were colonized mostly by Trypodendron lineatum and Tomicus minor, and to a lesser extent by Tomicus piniperda, which dominated in trap trees. Tomicus piniperda and T. lineatum preferred thicker stems; however, T. minor, Hylurgops palliatus and Pityogenes bidentatus preferred thinner ones. The application of the new sampling method helped to increase the accuracy of niche segregation among insect species. The results of niche segregation indicate bark beetles exhibited spatial specialization in the use of resources, mainly related to the moisture content of breeding material and the availability of food resources which is the main factor determining the coexistence of bark beetles in the same environment.