Attraction of red turpentine beetle and other Scolytinae to ethanol, 3‐carene or ethanol + 3‐carene in an Oregon pine forest

1. Red turpentine beetle Dendroctonus valens LeConte is a non‐aggressive bark beetle in North America that attacks weakened or recently dead pines, as well as their fresh logs or stumps. Fire‐injured ponderosa pines releasing stress‐induced ethanol are often attacked. The oleoresin from these trees frequently contains 3‐carene as a major component mixed with α‐ or β‐pinene. 3‐Carene lures usually attract more D. valens than α‐ or β‐pinene lures or 1 : 1 : 1 mixtures, whereas the attraction of ethanol + 3‐carene lures has never been tested.
2. Funnel traps with ethanol, 3‐carene or ethanol + 3‐carene lures, and a no lure blank, were set‐up as a randomized complete block design in a pine forest near La Pine, Oregon, U.S.A., from 23 April until 11 June 2015.
3. Dendroctonus valens, Hylastes nigrinus, Hylurgops reticulatus, Hylurgops porosus and Hylastes gracilis exhibited similar responses, with highest numbers captured in traps with ethanol + 3‐carene. The response by the first three species was confirmed as synergistic.
4. Ips spp., Pityogenes spp., Gnathotrichus spp., Pachysquamus subcostulatus and Hylastes macer composed a second group whose numbers captured with ethanol lures were similar or greater than the 3‐carene or ethanol + 3‐carene lures. A reduced H. macer response to ethanol + 3‐carene was confirmed as an interruption.