| Title: | "Trap Assays of the Walnut Twig Beetle, Pityophthorus juglandis Blackman (Coleoptera: Curculionidae: Scolytinae), Reveal an Effective Semiochemical Repellent Combination" |
| Author(s): | Audley JP; Bostock RM; Seybold SJ; |
| Address: | "USDA Forest Service, Pacific Southwest Research Station, Davis, CA, 95618, USA. Jackson.audley@usda.gov. Department of Plant Pathology, University of California, Davis, CA, 95616, USA. USDA Forest Service, Pacific Southwest Research Station, Davis, CA, 95618, USA" |
| DOI: | 10.1007/s10886-020-01228-9 |
| ISSN/ISBN: | 1573-1561 (Electronic) 0098-0331 (Linking) |
| Abstract: | "Thousand cankers disease (TCD), is an invasive insect-disease complex caused by the walnut twig beetle, Pityophthorus juglandis, and fungal pathogen, Geosmithia morbida. Semiochemical interruption is a viable option for protecting walnut trees from P. juglandis attack. The goal of this study was to test beetle responses to potential repellent compounds. The results of five, flight-intercept assays are reported. Assays 1-3 tested four compounds at variable release rates: (S)-(-)-verbenone, (R)-(+)-verbenone, racemic chalcogran, and racemic trans-conophthorin. Trapping results indicated that the highest release rate tested for each compound was the most effective in reducing the number of beetles caught. (S)-(-)-Verbenone was the least effective, reducing P. juglandis trap catches by 66%. (R)-(+)-Verbenone reduced the number of P. juglandis by 84%. Neither enantiomer of verbenone performed as well as chalcogran or trans-conophthorin, which both reduced the number of beetles caught by ca. 98%. Following individual assays, the most effective compounds were tested in subtractive-combination assays. Combinations of high release rates for (R)-(+)-verbenone, trans-conophthorin, and two stereoisomers of limonene (tested in a previous study) were tested in two assays. The subtractive-combination assays were inconclusive in that trap catches were similar across all treatments. All combination treatments were highly effective, achieving approximately 99% reduction in the number of beetles caught. Based on the trapping results, commercial availability, and cost of the semiochemicals tested, we conclude that a combination of (R)-(+)-limonene, trans-conophthorin, and (R)-(+)-verbenone constitutes an effective tool for reducing P. juglandis trap catches" |
| Keywords: | Animals Bicyclic Monoterpenes/chemistry/metabolism Female Hypocreales/*physiology Insect Repellents/metabolism Isomerism Juglans/*chemistry Limonene/metabolism Male Pheromones/*metabolism Plant Diseases/prevention & control Spiro Compounds/chemistry/metab; |
| Notes: | "MedlineAudley, Jackson P Bostock, Richard M Seybold, Steven J eng 16-SCBGP-CA-0035/Agricultural Marketing Service/ 2020/10/28 J Chem Ecol. 2020 Dec; 46(11-12):1047-1058. doi: 10.1007/s10886-020-01228-9. Epub 2020 Oct 27" |
