Host and non‐host odour signals governing host selection by the pine shoot beetle, Tomicus piniperda and the spruce bark beetle, Hylurgops palliatus (Col., Scolytidae)

  Tomicus piniperda and Hylurgops palliatus colonize susceptible host trees by responding to host‐specific odour signals as well as by avoiding volatiles emanating from non‐host conifers. In the field, the pine shoot beetle, T. piniperda , responded in high numbers to natural odour sources provided by their host tree, Pinus sylvestris , while the non‐host conifers Larix decidua , Picea abies , or Pseudotsuga menziesii were significantly less attractive. In contrast, the spruce bark beetle, Hylurgops palliatus , preferentially responded to its main host, P. abies . Furthermore, T. piniperda attacks on P. sylvestris bolts decreased in presence of bark and wood particles from the non‐host P. abies , whereas particles from P. menziesii appeared not to affect T. piniperda attacks. Apparently, tree‐specific volatiles act at close range as specific signals that lead to the successful discrimination and colonization of the respective host tree species.