Verbenone interrupts attraction to host volatiles and reduces attack on Pinus tabuliformis (Pinaceae) by Dendroctonus valens (Coleoptera: Scolytidae) in the People's Republic of China

The introduced red turpentine beetle, Dendroctonus valens LeConte, is one of the most economically important forest pests in the People's Republic of China, having killed more than 6 million pines in recent years. There is an urgent need to develop effective behavioral chemicals to monitor and control D. valens in the People's Republic of China, as well as in its native range in North America. We tested host kairomones as a 1:1:1 blend of α-pinene, β-pinene, and Δ-3-carene (releasing in the same proportions) for monitoring D. valens populations in the People's Republic of China. We also tested two release systems of verbenone for protection of Pinus tabuliformis Lawson from D. valens attack: (1) polyethylene bubblecaps (BCs) filled with 800 mg of nearly pure verbenone (releasing 18 mg/tree per day) and (2) a sprayable water suspension of microencapsulated (MEC) verbenone (releasing about 100 mg/tree per day). The host-volatile blend trapped substantial numbers of both sexes of adult beetles, up to 15 beetles per day, proving its potential for monitoring. Both of the verbenone release systems significantly reduced D. valens trap catch, and there was no difference between the BC treatment and the MEC treatment. Both release systems also reduced beetle attack on trees to the same level as unbaited controls, from a mean of 5.1 per tree to a mean of 0.7 per tree (for both release systems), suggesting that the treatments may also reduce tree mortality. Le dendroctone rouge de l'épinette, Dendroctonus valens LeConte, une espèce introduite, est, sur le plan économique, l'un des plus importants ravageurs des forêts de République populaire de Chine; il a détruit plus de 6 millions de pins (Pinaceae) au cours des dernières années. Il y a donc un besoin urgent d'identifier les substances chimiques efficaces qui régissent son comportement, de façon à en faire la surveillance et le contrôle en République populaire de Chine, aussi bien qu'on le fait sur son aire de répartition originale en Amérique du Nord. Nous avons testé les kairomones de l'hôte en utilizant un mélange 1:1:1 de α-pinène, de β-pinène et de Δ-3-carène (libérées en proportions égales) pour l'évaluation des populations de D. valens en République populaire de Chine. Nous avons aussi testé deux systèmes de libération de verbénone pour protéger Pinus tabuliformis Lawson des attaques de D. valens : (1) des capsules émettrices de polythène (bubblecaps, BCs) contenant 800 mg de verbénone presque pure (libérant