Conservation
of a threatened beetle
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A major current research direction is the spatial dynamics of a threatened insect, the Valley Elderberry Longhorn Beetle, Desmocerus californicus dimorphus. For further information about the beetle see Theresa Talley's website: http://web.mac.com/tsinicrope/iWeb/Site/VELB%20info/VELB%20info.html Field surveys were used to investigate the importance of different spatial scales for the persistence of this federally protected species, which is restricted to riparian habitats in California’s Central Valley. This project, in collaboration with Dr. Sharon K. Collinge (U. of Colorado), Jaymee T. Marty and Cheryl B. Barr (Essig Museum of Entomology, U. C. Berkeley) demonstrated that local populations showed frequent turnover. However, at the watershed scale there was no extinction or colonization over 10 years (Collinge et al. 2001). Isolated sites were less likely to be occupied by the beetle. This is valuable information because it suggests that a watershed-scale approach is necessary for successful conservation. More recent work in collaboration with my Ph.D. student Theresa Talley has begun to investigate the relationship between the beetle and its host plant, elderberry, which needs to reach a minimum size (and age) before being suitable for the beetle. When habitat is destroyed and new habitat is planted through mitigation there is a time period before the habitat becomes suitable; this ‘lag time’ means that even when habitat losses are well-mitigated there is a temporally substantial loss of habitat that could destabilize populations. We are using habitat restoration, mitigation and natural sites to explore site age, the amount of suitable beetle habitat available and how this influences population presence and abundance. This project will yield both practical information about mitigation and habitat restoration practices and useful ecological information about a species which is puzzling because it persists at low densities. Funding for this work is being sought through the Sacramento Area Flood Control Association, Sacramento County Parks, and a CalFed grant was submitted in collaboration with The Nature Conservancy’s Sacramento River Office in Chico, CA in October 2001. This work will help produce a population viability model, which will be tested and used to aid management decisions. Current mitigation efforts have largely been failing and there is a need to acquire more information about the relationship between the beetle and its host plant to define habitat suitability and suitable management practices. The project uses field surveys and spatially explicit population viability models to predict habitat suitability and understand the spatial dynamics of this system. A long- term aim is to improve the Species Recovery Plan and Habitat Management Plan for the beetle. Current and Past Collaborators on this work include: Theresa Talley, Dept. Environmental Science and Policy at U. C. Davis (tstalley AT ucdavis.edu). Gary Huxel, University of South Florida. Gary's Homepage (ghuxel AT chuma1.cas.usf.edu). Sharon K. Collinge, University of Colorado. Sharon's Homepage (Sharon.Collinge AT Colorado.edu) |
Adult beetles are approximately 2 cm (3/4") long and are rarely seen.
The beetle feeds only on a single plant species, elderberry (Sambucus spp.).
Beetles spend most of their lives burrowing inside elderberry stems. They leave distinctive emergence holes of 6-10mm diamteter. |
