We investigated host preference of the pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), in a large-scale field study in 1997 and 1998. This Eurasian pest, first discovered in North America in 1992, is capable of developing and shoot-feeding in many North American pines. We hypothesized, however, that T. piniperda would preferentially colonize Scots pine (Pinus sylvestris L.), a Eurasian species, more frequently than North American red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb.). We placed freshly cut Scots, red, and jack pine logs in Scots, red, and jack pine forest stands each year in southwestern Michigan, where T. piniperda populations have been established for several years, and in central and northern Michigan, where T. piniperda populations were low to rare. Following T. piniperda progeny emergence, logs were retrieved and debarked and T. piniperda attack density was determined for each log. Tomicus piniperda colonized 80%90% of the pine logs in the southwestern Michigan stands compared with 2%19% of logs in the central Michigan stands. No logs in the northern Michigan stands were colonized by T. piniperda in either year. In the southwestern pine stands, T. piniperda attack densities were significantly greater on Scots pine logs than on jack and red pine logs, regardless of stand species.
Scots pine susceptibility to attack by Tomicus piniperda (L) as related to pruning date and attack density