Insects on lodgepole pine in Sweden — current knowledge and potential risks

Eighty species of forest insects have thus far been recorded feeding on lodgepole pine in the Nordic countries (61 in Sweden). The list includes species that have Scots pine as their main host and which feed on needles, flowers, cones, and shoots, as well as species boring in the phloem and xylem of dead or dying Norway spruce. Contrary to our expectations, most of the insect species that have colonised lodgepole pine in Sweden can be considered specialists (with regard to host plant range and feeding mode) rather than generalists. We suggest that the current dominance of specialised insect herbivores is related to the similarity in chemistry and morphology between lodgepole and Scots pine.Only a few of the species considered to be pests have caused considerable damage in lodgepole pine stands in the Nordic countries. The most severe damage has been caused by the needle feeders Neodiprion sertifer and Anthonomus phyllocola. Hylobius abietis, the most harmful forest insect species in Scandinavia, attacks lodgepole pine seedlings to about the same degree as it attacks Scots pine and Norway spruce and causes similar levels of mortality. Other pest species reported to have caused considerable damage to lodgepole pine are Pissodes validirostris (cones) and Rhyacionia boulliana (shoots).No insect species native to North America and living on lodgepole pine have yet to become established in the Nordic countries since the introduction of this exotic tree species. The risk of large-scale damage in Sweden is discussed in relation to the distribution and management of lodgepole pine. (C) 2001 Elsevier Science B.V. All rights reserved.