Comparing risks from native and exotic bark beetles to the health of Great Lakes forests

摘要

Lowland coniferous forests in several Great Lakes states are experiencing significant die back and mortality. Tamarack is the dominant species in many of these stands. Tamarack mortality may be caused by attacks from the native eastern larch beetle, Dendroctonus simplex, which have also increased in intensity in recent years. Overwintering larvae and adults of this beetle differ in cold hardiness. Recent mild winters have increased the likelihood of adult survivorship through the winter. At the sametime, a new bark beetle, the Mediterranean pine engraver, Orthotomicus erosus, has recently invaded California. What risk does this new bark beetle pose for conifers in the north central U.S.? Orthotomicus erosus may attack tamarack, though pines are more suitable. The beetle seems unlikely to survive the winter in the north central U.S., but may become problematic in the southeastern U.S.