β‐Pinene + ethanol attracts more red turpentine beetles than carene+ ethanol, with or without traces of frontalin, at prescribed burn or thinned sites

Abstract

Abstract Red turpentine beetle, Dendroctonus valens LeConte (Coleoptera: Curculionidae: Scolytinae), previously responded more strongly to (−)‐β‐pinene + ethanol than (+)‐3‐carene + ethanol lures at sites burned the prior year by wildfire in Oregon and northeastern California, whereas at a thinned‐unburned Arizona site (+)‐3‐carene + ethanol was the stronger attractant. This discrepancy was further examined to tease apart whether D. valens attraction varies by region or previous forest disturbance types. Here, (−)‐β‐pinene + ethanol and (+)‐3‐carene + ethanol lures were tested in pine stands at two Oregon sites disturbed the previous year by a prescribed burn or thinning only. Both lures were tested also with or without trace amounts of the pheromone frontalin, as its presence enhanced attractions in China but had not been tested in North America. At both sites, regardless of prior forest disturbance, (−)‐β‐pinene + ethanol lures attracted the most beetles. Lures releasing trace frontalin attracted more beetles than their corresponding lures without it at both sites, except in one case. Overall, previous year disturbances from disparate management treatments had minimal influence on lure attraction to D. valens. For detection, monitoring or management (−)‐β‐pinene + ethanol + frontalin in trace amounts attracts the most beetles of lures tested to date in Pacific Northwest pine forests.