Effect of different semiochemicals blends on spruce bark beetle, Ips typographus (Coleoptera: Scolytidae)

The spruce bark beetle, Ips typographus, is a recent new introduction to the Qilian Mountains of China. An outbreak of these beetles has infested over 0.03 million hectares of spruce forests in this area. Although primary attraction to volatiles has been clearly demonstrated for I.typographus, the existence and role of attraction to insect-produced pheromones have been widely debated. Currently, commercial lures for I.typographus include only the volatiles ipsdienol, cis-verbenol, trans-verbenol, 2-methyl-3-buten-2-ol and 2-phenylethanol in Europe. Several potential pheromone candidates have been identified for I.typographus. Our GCMS and GCFID analyses volatiles from hindgut extracts of I.typographus in different attack phases demonstrated that the 2-methyl-3-buten-2-ol, ipsdienol, cis-verbenol and trans-verbenol as major hindgut components, and ipsenol, 2-phenylethanol, trans- myrtenol and verbenone as minor components. We tested various combinations of semiochemical candidates, to determine an optimal blend. Our results suggest that addition of 2-methyl-3-buten-2-ol to either ipsenol alone, or to blends of ipsenol and other semiochemical candidates, significantly enhanced attraction of I.typographus. Therefore, a simple lure consisting of ipsenol and 2-methyl-3-buten-2-ol would be an optimal blend of I.typographus in the Qilian Mountains, China. We conclude that this optimal semiochemical blend may provide an effective biological pest control method for use in forest ecosystem against I.typographus.