endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Endemic to the San Joaquin and Sacramento River basins of California's Central Valley from southern Shasta County south to Fresno County (USFWS 2006). It is found mainly within a km of the rivers, and spotty within this range. It is replaced by a different subspecies on the western side of the mountains.
Catalog Number: USNM
Collection: Smithsonian Institution, National Museum of Natural History, Department of Entomology
Verification Degree: Alleged type specimen status verified from secondary sources
Collector(s): B. Thompson
Year Collected: 1921
Locality: Sacramento; Cal, Sacramento, California, United States
- Type: Fisher, W. S. 1921. Proceedings of the Entomological Society of Washington. 23 (9): 207.
Comments: Primarily found in riparian wooded areas where elderberries occur, but it has occasionally been found with these plants in more upland habitats.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
It is thought to occasionally disperse several miles, but generally stays among the elderberry habitats.
Comments: Larvae bore in the stems of elderberries, Sambucus, and adults feed on their foliage. Oviposition occurs on stems with diameter greater than about 2.5 cm. It is likely, but uncertain, that any Sambucus taxon present is potential foodplant, although some authors recognize more than one species in the southwestern USA.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 80
Comments: See USFWS (2012). Based mostly on California Natural Diversity Database, they identify about 26 occurrences since 1980, but a few of these produced no records during the most recent surveys, and a few unknown occurrences could very well exist.
Life History and Behavior
Comments: Adults occur from March to June, larvae occur year-round. The larval stage reportedly often takes two years to complete (USFWS, 2012 and references cited therein).
NatureServe Conservation Status
Rounded Global Status Rank: T2 - Imperiled
Reasons: The subspecies' rank was T2 for many years based on a California state rank from 2000 and the beetle is endemic to that state. This beetle is somewhat more widespread than was formerly believed and has been proposed for delisting under the US Endangered Species Act. The calculated rank is T3, but there is some uncertainty as to how many viable, extant populations the 26 records since 1980 actually represent, although almost certainly not as many as 26, especially with several negative results during the most recent efforts. However, there could be a few undiscovered occurrences. T2T3 better expresses the range of uncertainty.
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
Date Listed: 08/08/1980
Lead Region: California/Nevada Region (Region 8)
Where Listed: Entire
Population location: Entire
Listing status: T
For most current information and documents related to the conservation status and management of Desmocerus californicus dimorphus , see its USFWS Species Profile
Global Short Term Trend: Unknown
Global Long Term Trend: Decline of 50 to >90%
Degree of Threat: High
Comments: Because this species is only found in association with its host plant, Sambucus spp., the major threat is habitat loss due to conversion to agriculture and urbanization. It is estimated that 90% of the riparian habitat in the Central Valley has been lost since the late 1800's, resulting in fragmented and isolated remnants.
Although conversion to agriculture has probably reached its maximum extent in the Central Valley, the conversion of agricultural lands into urban development continues to pose a threat.
Flood control activities and pesticide use (including insecticides) are also ongoing threats.
See USFWS (2012) for a more detailed assessment of threats.
Restoration Potential: Restoration of connectivity, e.g., eliminating gaps in the presence of the foodplant, would probably be very useful in fragmented habitats. Generally increasing the number or size of foodplants in occupied habitat should increase populations. The potential for the species to re-establish, or be reintroduced, to unoccupied restored habitat is unknown.
Global Protection: Several to many (4-40) occurrences appropriately protected and managed
Comments: According to USFWS (2012) at least 10 occurrences have substantial protection. Others may have some level of protection. Some are unprotected.
Relevance to Humans and Ecosystems
Stewardship Overview: Since this is a listed subspecies, although likely to be delisted (USFWS, 2012), current or recent USFWS online information should be consulted. In general the goal would be to maintain relatively contiguous habitat patches with mature elderberry bushes (or small trees) in healthy, natural or restored riparian forest or woodland. Apparently only stems or branches with diameters over 2.5 cm are used for oviposition. Obvious management issues involve not damaging the foodplants. For example if they are cut, any larvae in the portion removed would almost certainly die unless perhaps if they are very close to pupation. It is not likely, maybe not even possible, they could find a new plant and establish in it. Damaged or otherwise stressed stems should not be pruned off, because these may be preferred hosts, and at least they can support larvae. Herbiciding would similarly indirectly kill any larvae in the affected stems. Insecticide drift is an issue in agricultural lands and possibly others, with most kinds (other than Bt) potentially affecting adults and newly hatched larvae that have not yet burrowed into the stems. Control of invasive plants that suppress elderberries would also be a likely management issue. Water management issues might also be of concern.
Valley elderberry longhorn beetle
The valley elderberry longhorn beetle, Desmocerus californicus dimorphus, is a subspecies of longhorn beetle native to the riparian forests of the Central Valley of California from Redding to Bakersfield. It is listed as a Federally threatened species, although it is likely to be removed from the endangered species list.
Valley elderberry longhorn beetles (Desmocerus californicus dimorphus) are stout-bodied. Males range in length from about 1.25–2.5 cm (½–1 in; measured from the front of the head to the end of the abdomen) with antennae about as long as their bodies. Females are slightly more robust than males, measuring about 1.9–2.5 cm (¾–1 in), with somewhat shorter antennae. Adult males have red-orange elytra (wing covers) with four elongate spots. The red-orange fades to yellow on some museum specimens. Adult females have dark-colored elytra.
There are four stages in the animal's life: egg, larva, pupa and adult. The species is nearly always found on or close to its host plant, elderberry (Sambucus species). Females lay their eggs on the bark. Larvae hatch and burrow into the stems. The larval stage may last 2 years, after which the larvae enter the pupal stage and transform into adults. Adults are active from March to June, feeding and mating. Adults have been observed feeding on the leafy foliage of the elderberry plant.
It appears that in order to serve as habitat, the shrubs must have stems that are 2.5 cm (1 in) or greater in diameter at ground level. Use of the plants by the animal is rarely apparent. Frequently, the only exterior evidence of the shrub's use by the beetle is an exit hole created by the larva just before the pupal stage. Field work along the Cosumnes River and in the Folsom Lake area suggests that larval galleries can be found in elderberry stems with no evidence of exit holes. The larvae either succumb before constructing an exit hole or are not far enough along in the developmental process to construct an exit hole.
- Sacramento Zone — An area in the city of Sacramento enclosed on the north by the Route 160 Freeway, on the west and southwest by the Western Pacific railroad tracks, and on the east by Commerce Circle and its extension southward to the railroad tracks.
- American River Parkway Zone — An area of the American River Parkway on the south bank of the American River, bounded on the north by latitude 38 37'30" N, and on the South and east by Ambassador Drive and its extension north to latitude 38 37'30" N, River Bend Park, and that portion of the American River Parkway northeast of River Bend Park, west of the Jedediah Smith Memorial Bicycle Trail, and north to a line extended eastward from Palm Drive.
- O'Connor Lakes Ripirain restoration zone sponsored by California's Department of Fish and Game and the wildlife conservation board Location: Sutter and Yuba Counties - 10 miles south of Marysville and Yuba City on the Feather River. Access: Access gained from Star Bend fishing access on Feather River Blvd.
Extensive destruction of California's Central Valley riparian forests has occurred during the last 150 years due to agricultural and urban development. According to some estimates, riparian forest in the Central Valley have declined by as much as 89% during that time. The valley elderberry longhorn beetle, though wide-ranging, is in long-term decline due to human activities that have resulted in widespread alteration and fragmentation of riparian habitats, and to a lesser extent, upland habitats, which support the beetle.
The primary threats to survival of the beetle include:
- loss and alteration of habitat by agricultural conversion.
- inappropriate grazing.
- levee construction, stream and river channelization, removal of riparian vegetation and rip-rapping of shoreline.
- nonnative animals such as the Argentine ant, which may eat the early phases of the beetle.
- recreational, industrial and urban development.
Insecticide and herbicide use in agricultural areas and along road right-of-ways may be factors limiting the beetle's distribution. The age and quality of individual elderberry shrubs/trees and stands as a food plant for beetle may also be a factor in its limited distribution.
- "Desmocerus californicus dimorphus". Integrated Taxonomic Information System.
- "Valley Elderberry Longhorn beetle". United States Fish and Wildlife Service.
- Barr, C. 1991. The Distribution, Habitat, and Status of the Valley Elderberry Longhorn Beetle Desmocerus californicus dimorphus. Sacramento, CA.
- Eng, L. L., 1984. Rare, threatened and endangered invertebrates in California riparian systems. In: California riparian systems Ecology, conservation, and productive management, ed. R. E. Warner and K. M. Hendrix. Berkeley: University of California Press.
- Thelander, C. ed. 1994. Life on the edge: a guide to California's endangered natural resources. BioSystem Books. Santa Cruz, CA. p 414-415.
- U.C. Berkeley, Essig Museum of Entomology. California's Endangered Insects.
- U.S. Fish & Wildlife Service. 1980. Listing the Valley elderberry longhorn beetle as a threatened species with critical habitat. (PDF) Washington, DC.
- U.S. Fish & Wildlife Service. 1984. Valley elderberry longhorn beetle recovery plan. Portland, Oregon.
- U.S. Fish and Wildlife Service. 1996. Valley elderberry longhorn beetle consultation with the U.S. Army Corps of Engineers. Sacramento, California. Appendix: Conservation Guidelines for the Valley Elderberry Longhorn Beetle, Updated July 9, 1999.
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