Red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Scolytidae), response to host semiochemicals in China

The response of the introduced red turpentine beetle, Dendroctonus valens LeConte, to host semiochemicals in Shanxi Province, China, was distinctly different from that reported in previous studies conducted in the western part of the native range of D. valens in the central Sierra Nevada, CA. This finding suggests either that there is regional variation in D. valens response to host volatiles in North America or that the species underwent rapid adaptation after its introduction into Asia. In the Chinese population of D. valens, (+) -3-carene was the most attractive host monoterpene tested in studies conducted in 2002 using multiple funnel traps suspended in a Pinus tabuliformis stand. It attracted significantly more beetles than did any other single semiochemical or any of the ternary or quaternary blends tested, including the standard D. valens blend used in North America [a 1:1:1 blend of (+)-alpha-pinene, (-)-beta-pinene, and (+)-3-carene]. (+)-alpha-Pinene and (-)-beta-pinene, presented individually, were not significantly more attractive than controls. Adding limonene to the standard lure decreased response of D. valens but not significantly. A new type of semiochemical release vial was tested using a range of release rates of a 1:1:1 blend of (+)-a-pinene, (-)-beta-pinene, and (+)-3-carene. The rates ranged from 150 to 210 mg/d, and these were compared with the standard North American lure, which releases approximate to110 mg/d. The most attractive of these vials, which released approximate to150 mg/d, captured significantly more beetles than did the standard release device; however, increasing the release rate beyond 150 mg/d did not further increase trap catch. The implications of our results for the phylogenetic geography of D. valens and its management as an invasive species are discussed.