Population Dynamics of the Northern Tamarisk Beetle (Diorhabda carinulata) in the Colorado River Basin By Levi R. Jamison and Charles van Riper III Open-File Report 2018–1070 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Deputy Director exercising the authority of the Director U.S. Geological Survey, Reston, Virginia: 2018 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov/ or call 1–888–ASK–USGS (1–888–275–8747). For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Jamison, L.R., and van Riper, C., III, 2018, Population dynamics of the northern tamarisk beetle (Diorhabda carinulata) in the Colorado River Basin: U.S. Geological Survey Open-File Report 2018– 1070, 67 p., https://doi.org/10.3133/ofr20181070. ISSN 2331-1258 (online) Contents Introduction .................................................................................................................................................... 1 References Cited ........................................................................................................................................... 3 Chapter 1. The Influence of Tamarix ramosissima Defoliation on Population Movements of the Northern Tamarisk Beetle (Diorhabda carinulata) on the Colorado Plateau .......................................................... 6 Abstract ...................................................................................................................................................... 6 Introduction ................................................................................................................................................ 6 Methods ..................................................................................................................................................... 7 Study Sites ............................................................................................................................................. 7 Survey Techniques ................................................................................................................................ 8 Results ....................................................................................................................................................... 9 Dolores River ......................................................................................................................................... 9 San Juan River .................................................................................................................................... 10 Discussion ................................................................................................................................................ 12 Conclusion ............................................................................................................................................... 14 Acknowledgments .................................................................................................................................... 15 References Cited ..................................................................................................................................... 15 Chapter 2. Utilizing Temperature, Day Length, and Diorhabda carinulata Geographic Distribution for Predicting the Intensity of Tamarix Species Defoliation ........................................................................ 17 Abstract .................................................................................................................................................... 17 Introduction .............................................................................................................................................. 17 Methods ................................................................................................................................................... 19 Study Sites ........................................................................................................................................... 19 Field Methodology ............................................................................................................................... 19 Data Analysis ....................................................................................................................................... 20 Results ..................................................................................................................................................... 22 Influence of Abiotic Cues on Seasonal Timing ..................................................................................... 22 Spatial Dynamics of D. carinulata and Defoliation ............................................................................... 27 Discussion ................................................................................................................................................ 37 Influence of Abiotic Cues on Seasonal Timing ..................................................................................... 37 Spatial Dynamics of D. carinulata and Defoliation ............................................................................... 38 Conclusion ............................................................................................................................................... 40 Management Implications ........................................................................................................................ 42 Acknowledgments .................................................................................................................................... 42 References Cited ..................................................................................................................................... 42 Appendix 1. Temperature and Day-Length Data for Study Sites in the Colorado River basin, 2011–12 ..... 46 iii Figures 1. Map of the Colorado, San Juan, San Miguel, and Dolores Rivers in Utah and Colorado, showing locations of study sites on the Dolores and San Juan Rivers. .......................................................... 8 2. Distribution of Diorhabda carinulata adults and larvae and resulting tamarisk defoliation along the Dolores River between the confluences of the Colorado River and the San Miguel River in August 2008. .............................................................................................................................................. 10 3. Comparative distributions of Diorhabda carinulata adults recorded along the Dolores River in 2008–10.......................................................................................................................................... 11 4. Comparative distributions of Diorhabda carinulata adults and larvae and tamarisk defoliation levels recorded in late July 2010 along the San Juan River between Bluff, Utah, and Clay Hills Crossing, Utah ................................................................................................................................................ 13 5. Map of the Colorado and San Juan Rivers in Arizona and New Mexico showing study site locations. ........................................................................................................................................ 20 6. Diorhabda carinulata population distributions in 2011 at the San Juan and Marble Canyon study sites. ............................................................................................................................................... 22 7. Average daily temperatures at study sites in the Colorado River basin, with timing of initial reproductive activity in 2011 and 2012 ........................................................................................... 26 8. Mean defoliation levels at the Marble Canyon, Grand Canyon, and San Juan study sites in the Colorado River basin in 2011. ........................................................................................................ 27 9. Monthly distributions of Diorhabda carinulata along the San Juan River near Farmington, New Mexico, along the Colorado River in Marble Canyon and in the Grand Canyon, Arizona ............... 28 10. Number of first-summer-generation larvae versus defoliation level one month later at study sites in the Colorado River basin in 2011. .................................................................................................. 31 11. Number of Diorhabda carinulata versus defoliation level at study sites in the Colorado River basin midsummer 2011 ............................................................................................................................ 32 12. Spatial distributions of Diorhabda carinulata larvae and respective defoliation levels along the San Juan River near Farmington, New Mexico, along the Colorado River in Marble Canyon and