The elusive search for an effective repellent against voles: an assessment of anthraquinone for citrus crops
Vole (Cricetidae) girdling of tree trunks is a common form of damage experienced by tree and vine growers throughout much of the Northern Hemisphere. Management programs that effectively incorporate chemical repellents and vegetation management would be of substantial assistance to growers that experience such damage. Anthraquinone has proven effective as a repellent against voles in lab trials, yet controlled field tests of combined anthraquinone and vegetation management programs are lacking. Therefore, we established a mesocosm-based study in central California, USA, to test the efficacy of anthraquinone and vegetation management for reducing girdling damage caused by California voles Microtus californicus to Clementine citrus trees Citrus clementine under semi-field conditions. We observed a 90–100% reduction in girdling damage for trees following a single application of anthraquinone during two trials in summer and spring, respectively. Removal of vegetation around the base of trees further reduced damage during the summer sampling period, with no girdling observed on anthraquinone-treated trees that were surrounded by bare soil. We did not observe this same relationship during spring, and we observed no relationship between vegetation management in the absence of anthraquinone treatments in either seasonal trial, suggesting that vegetation management had a lesser impact on vole girdling than anthraquinone applications. We observed no decrease in efficacy of anthraquinone across the duration of both sampling periods (5–6 weeks), indicating substantial longevity for anthraquinone. Anthraquinone appears to have substantial utility for minimizing vole girdling damage. Field testing is warranted for additional mammalian species to determine potential uses for other taxa.
KeywordsAnthraquinone California vole Girdling Microtus californicus Repellent Vegetation management
We thank Ocean Mist and Sea Mist Farms for all of the assistance and resources they provided during this project. We also thank D. Langone with Vino Farms and R. Long for access to their property for vole captures, and to N. O’Connell for providing valuable feedback during the initial stages of this project. We greatly appreciate Arkion® Life Sciences providing anthraquinone for our use. This project was supported in part by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through Grant 1-SCBGP-CA-0046. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA. Additional support was provided by the University of California’s Division of Agriculture and Natural Resources.
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the University of California, Davis (Study Protocol 19052).
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