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Fish & Wildlife Service Seeks Comments on Rule Withdrawal to Delist Valley Elderberry Longhorn Beetle Under Endangered Species Act(Targeted News Service Via Acquire Media NewsEdge) Targeted News Service WASHINGTON, Sept. 18 -- The U.S. Fish & Wildlife Service published the following proposed rule in the Federal Register: Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule To Remove the Valley Elderberry Longhorn Beetle From the Federal List of Endangered and Threatened Wildlife A Proposed Rule by the Fish and Wildlife Service on 09/17/2014 Publication Date: Wednesday, September 17, 2014 Agencies: Department of the Interior Fish and Wildlife Service Dates: The Service is withdrawing the proposed rule published October 2, 2012 (77 FR 60238) as of September 17, 2014. Entry Type: Proposed Rule Action: Proposed rule; withdrawal. Document Citation: 79 FR 55873 Page: 55873 -55917 (45 pages) CFR: 50 CFR 17 Agency/Docket Numbers: Docket No. FWS-R8-ES-2011-0063 FXES11130900000C2-123-FF09E32000 RIN: 1018-AV29 Document Number: 2014-21585 Shorter URL: https://federalregister.gov/a/2014-21585 Action Proposed Rule; Withdrawal. Summary We, the U.S. Fish and Wildlife Service (Service), withdraw the proposed rule to remove the valley elderberry longhorn beetle (Desmocerus californicus dimorphus) from the Federal List of Endangered and Threatened Wildlife under the Endangered Species Act of 1973 (Act), as amended. This withdrawal is based on our determination that the proposed rule did not fully analyze the best available information. We find the best scientific and commercial data available indicate that the threats to the species and its habitat have not been reduced to the point where the species no longer meets the statutory definition of an endangered or threatened species. DATES: The Service is withdrawing the proposed rule published October 2, 2012 (77 FR 60238) as of September 17, 2014. ADDRESSES: The withdrawal of our proposed rule, comments and materials we received, and supplementary documents are available on the Internet at http://www.regulations.gov at Docket No. FWS-R8-ES-2011-0063. All comments, materials, and supporting documentation that we considered in this final agency action are available by appointment, during normal business hours, at: U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office, 2800 Cottage Way, Suite W-2605, Sacramento, California 95825; telephone 916-414-6600; or facsimile 916-414-6713. FOR FURTHER INFORMATION CONTACT: Jennifer Norris, Field Supervisor, Sacramento Fish and Wildlife Office (see ADDRESSES section). Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339. SUPPLEMENTARY INFORMATION: Executive Summary Why we need to publish this document. Section 4 of the Act and its implementing regulations (50 CFR part 424) set forth the procedures for revising the Federal Lists of Endangered and Threatened Wildlife and Plants. Rulemaking is required to remove a species from the Federal Lists of Endangered and Threatened Wildlife and Plants, accordingly, we issued a proposed rule and 12-month petition finding on October 2, 2012 (77 FR 60238) to remove the valley elderberry longhorn beetle as a threatened species from the List of Endangered and Threatened Wildlife and to remove the designation of critical habitat for the subspecies. Based upon our review of public comments, comments from various Federal, county, and local agencies, peer review comments, comments from other interested parties, and new information that became available since the publication of the proposal, we reevaluated information in our files and our proposed rule. This document withdraws the proposed rule because the best scientific and commercial data available, including our reevaluation of information related to the species' range, population distribution, and population structure, indicate that threats to the species and its habitat have not been reduced such that removal of this species from the Federal List of Endangered and Threatened Wildlife is appropriate. The basis for our action. A species may warrant protection under the Act if it is found to be endangered or threatened throughout all or a significant portion of its range. A species may be determined to be an endangered species or threatened species because of one or more of the five factors described in section 4(a)(1) of the Act: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. Based on our evaluation of the best scientific and commercial data available pertinent to threats currently facing the species and threats that could potentially affect it in the foreseeable future, we determine that threats have not been reduced such that the species no longer meets the statutory definition of an endangered or threatened species. Peer review and public comment. We sought peer review comments from independent specialists to ensure that our proposed delisting designation was based on scientifically sound data, assumptions, and analyses. We invited these peer reviewers to comment on our proposal to remove the valley elderberry longhorn beetle from the Federal List of Endangered and Threatened Wildlife. We also considered all other comments and information received during the public comment periods. Summary of Changes From the Proposed Rule Based upon our review of public comments, comments from various Federal, county, and local agencies, peer review comments, comments from other interested parties, and new information that became available since the publication of the proposal (77 FR 60238; October 2, 2012), we reevaluated information in our files and our proposed rule, making changes as appropriate in this document. Where appropriate, we incorporated new information that became available since publishing the proposed rule, information received during the public comment periods, and in some cases provided additional discussion of information in our files that may not have been presented in adequate detail in the proposed rule. This document also provides important clarifications on the species' biology and threats to the species. Thus, this determination differs from the proposed rule as outlined below. (1) Based on the results of the information received from peer reviewers and the public, we concluded that some species distribution information in the proposed rule was incorrectly presented. As a result, we reevaluated the quality of distribution information (occurrences) for the valley elderberry longhorn beetle that was included in our previous summaries (e.g., Valley Elderberry Longhorn Beetle Recovery Plan (Recovery Plan) (Service 1984, entire); proposed and final listing rules (43 FR 35636; August 10, 1978; 45 FR 52803; August 8, 1980); 5-year review (Service 2006a); and proposed delisting rule (77 FR 60238; October 2, 2012)). This required a reanalysis of the original data sets in our files throughout the range of the species. (2) As a result of (1) above and our review of additional sources of information received during the open public comment periods, we reexamined existing information in our files. In this document, we provide either clarifications where necessary, additional or revised discussions where appropriate (e.g., Population Distribution and Current Distribution sections under Background), or incorporate and discuss new information received (e.g., Climate Change and Pesticide discussion under Factor E, preliminary survey results using aggregation pheromones under Population Structure in Background). (3) As a result of (1) and (2) above, as well as information received after the proposed rule published, we reevaluated and revised our description of the valley elderberry longhorn beetle's life history, and its population distribution, range, and occupancy. Our revised discussions are provided throughout the Background section. (4) We revised the Summary of Factors Affecting the Species section, incorporating new or revised information, where appropriate, in our assessments for these factors. The substantial changes to the Background section required us to complete a detailed examination of the five-factor analysis information presented in the proposed rule for each threat to determine whether the discussions were still valid or required revisions. Thus, our threats analysis and associated summaries may differ, where appropriate, from that presented in the proposed rule. The primary changes to this document as compared to the proposed rule are the result of our reanalysis of occurrence and distribution information of the valley elderberry longhorn beetle. Specifically, we restructured the five-factor analysis from our proposed rule to reflect our reanalysis of threats, including additional and more detailed information (e.g., invasive plants in Factor A and pesticides under Factor E). We provide a more extensive discussion of effects related to climate change in Factor A, and incorporate predictions from several regional climate models for the Central Valley region. We also incorporate detailed results of several studies (e.g., metapopulation analysis) and use this information to evaluate the current threats to the species. Finally, threats related to the effects of pruning (briefly mentioned in our proposed rule under a Factor E threat (Human Use) (77 FR 60263; October 2, 2012)) are discussed in this withdrawal under Factor A. (5) Based on our reanalysis and the changes described above under (1) through (4), and primarily as a result of the revised occurrence and distribution information that affects our evaluation of the factors impacting the species, we determined that the current and future threats are of sufficient imminence, intensity, or magnitude to indicate that the valley elderberry longhorn beetle is likely to become endangered within the foreseeable future throughout all of its range. Therefore, the valley elderberry longhorn beetle currently meets the definition of a threatened species, and we are withdrawing the proposed rule to delist the valley elderberry longhorn beetle. Background Previous Federal Actions Please refer to the Previous Federal Actions section of the valley elderberry longhorn beetle proposed delisting rule (77 FR 60238, October 2, 2012) for a detailed description of the previous Federal actions concerning this species. On October 2, 2012, we proposed to remove the designation of the valley elderberry longhorn beetle as a threatened species under the Act (77 FR 60238). We opened a 60-day public comment period on the proposed rule that closed on December 3, 2012. On January 23, 2013 (78 FR 4812), we announced a 30-day reopening of the public comment period for our October 2, 2012, proposed delisting rule for the species. Taxonomy and Species Description The valley elderberry longhorn beetle, Desmocerus californicus dimorphus, is a member of the family Cerambycidae, subfamily Lepturinae, and genus Desmocerus (Chemsak 2005, pp. 6-7); adults are approximately 0.5 to 0.8 inches (in) (13 to 21 millimeters (mm)) long (Chemsak 2005, p. 6). In North America, the genus Desmocerus includes three species (D. palliatus, D. californicus, D. aureipennis) and six subspecies (D. c. californicus, D. c. dimorphus, D. a. aureipennis, D. a. cribripennis, D. a. piperi, D. a. lacustris) in the United States and Canada (Chemsak 2005, pp. 4-12). Members of the genus Desmocerus are brightly colored and sexually dichromatic with antennal tubules that are not prominently produced at the apex (Chemsak 2005, pp. 2-3). The protonum (upper surface of the prothorax segment; the midsection (Evans and Hogue 2006, p. 293)) of the two Desmocerus californicus subspecies differ from the other two North American species (D. palliatus, D. aureipennis) with a disk that is densely, confluently punctate (with small depressions on the disk that flow or run together), but without large, irregular, and transverse rugae (ridges) that are about twice as long as broad (Chemsak 2005, p. 3). Along the foothills of the eastern edge of the California coast range and in the southern San Joaquin Valley, the valley elderberry longhorn beetle range may overlap or abut portions of its range with the similar-looking California elderberry longhorn beetle (Desmocerus californicus californicus) (Talley et al. 2006a, p. 5). Prior to 1972, the valley elderberry longhorn beetle was considered a separate and valid species (Halstead and Oldham 2000, p. 74). The two elderberry longhorn beetles are now considered two subspecies (Linsley and Chemsak 1972, pp. 7-8; Chemsak 2005, pp. 5-6). Valley elderberry longhorn beetle experts indicate that the small number of available specimens limits the ability to distinguish between the two types based on characteristics such as body length, elytra length and width, and antennal hair color (Talley et al. 2006a, p. 5). Thus, the two subspecies can be identified with certainty only by the adult male coloration, such that valley elderberry longhorn beetle males have predominantly red elytra (wing cases) with four dark spots, while California elderberry longhorn beetle males have dark metallic green to black elytra with a red border; females of the two subspecies are similar in appearance (Talley et al. 2006a, p. 4). Atypically colored (mostly dark) male elderberry longhorn beetles have been observed in both the center and eastern edge of the valley elderberry longhorn beetle's range (Talley et al. 2006a, p. 5). Talley et al. (2006a, p. 7) recommend a systematic geographic morphological and genetic study to determine the degree of overlap and interbreeding between the two subspecies. The obligate larval host plants for both elderberry longhorn beetles have been described as blue elderberry (Sambucus mexicana) and, to a lesser extent for the valley elderberry longhorn beetle, red elderberry (Sambucus racemosa) (Collinge et al. 2001, p. 104; Holyoak 2010, p. 1). However, the current treatment of Sambucus in California (Family Adoxaceae) describes three taxa: Blue elderberry (S. nigra subsp. caerulea), black elderberry (S. racemosa var. melanocarpa), and red elderberry (S. racemosa var. racemosa) (Bell 2012, p. 160). As noted previously by others (e.g., Talley et al. 2006a, p. 15), the taxonomic status of Sambucus is imprecise, and blue elderberry is currently described as "variable" and in need of further study (Bell 2012, p. 160). In this rule, we use the more general term, elderberry, to describe the host plant for the valley elderberry longhorn beetle since many of the elderberry surveys and their reported results do not distinguish, or do not identify, the two taxa known to be occupied by the valley elderberry longhorn beetle (i.e., blue elderberry and red elderberry). Local climate differences between the more coastal region occupied by the California elderberry longhorn beetle and the California Central Valley occupied by the valley elderberry longhorn beetle may promote different phenologies (e.g., flowering time) of the host plant and, therefore, differences in time of emergence for the two subspecies (Talley et al. 2006a, p. 6). Life History Similar to other beetles, the valley elderberry longhorn beetle goes through several developmental stages. These include an egg, four larval stages (known as "instars," with each instar separated by molting), pupa, and adult (Greenberg 2009, p. 2). As reported by Arnold (1984, p. 4), females lay eggs singly on elderberry leaves and at the junction of leaf stalks and main stems, with all eggs laid on new growth at the outer tips of elderberry branches. Based on observations of Desmocerus californicus females along the Kings River, Halstead and Oldham (1990, p. 24) stated that females laid eggs at locations on the elderberry branch where the probing ovipositor (i.e., the female's egg-laying organ) could be inserted. In a laboratory setting, Barr (1991, p. 46) found that the majority of eggs laid by a female valley elderberry longhorn beetle were attached to leaves and stems of foliage (provided as food), with a preference for leaf petiole-stem junctions, leaf veins, and other areas containing crevices and depressions. Eggs are approximately 0.09 to 0.12 in (2.3 to 3.0 mm) long and reddish-brown in color with longitudinal ridges (Barr 1991, p. 4). Eggs are initially white to bright yellow (Talley et al. 2006a, p. 8) and then darken to brownish white and reddish brown (Burke 1921, p. 451). Results of captive studies of Desmocerus californicus indicate the number of eggs produced per female vary, ranging from 8 to 110 (Burke 1921, p. 25; Arnold 1984, p. 4; Barr 1991, p. 51). Talley (2003, pp. 153-157) recorded a total of 136 larvae (and an additional 44 eggs that did not hatch) from one captive female valley elderberry longhorn beetle collected in 2002. Hatching success has been estimated at 50 to 67 percent of eggs laid, but survival rates of larvae are unknown (Talley et al. 2006a, p. 7). In a laboratory setting eggs hatched within a few days of oviposition (Talley 2003, p. 145), but in the natural setting, the time to eclosing (development from egg to first instar larvae) is unknown (Barr 1991, pp. 4-5). Based on laboratory observations, the first instar larvae may bore immediately into the green tissue of the elderberry stem at or near the egg site, or larvae may persist on the shrub surface for several hours (Halstead and Oldham 1990, p. 26). Previous studies of both subspecies of Desmocerus californicus (Burke 1921, p. 450; Linsley and Chemsak 1972, p. 4) estimated that the larval development rate inside the plant is 2 years, but laboratory observations have indicated that a 1-year cycle is possible (Halstead and Oldham 1990, p. 26). The boring of the larva creates a feeding gallery (set of tunnels) in the pith at the stem center (Burke 1921, p. 450; Barr 1991, pp. 4-5). While only one larva is found in each feeding gallery, multiple larvae can occur in one stem if the stem is large enough to accommodate multiple galleries (Talley et al. 2006a, p. 8). Prior to pupation, the final (fifth) instar larva chews a larger pupal cavity in the pith of the stem and creates an exit burrow through the hardwood just below the surface of the bark of the plant, creating an exit hole (Halstead and Oldham 1990, p. 23), but then returns inside the plant stem, plugging the hole with wood shavings (also known as frass) (Talley et al. 2006a, p. 8). These larvae move back down the feeding gallery to the enlarged pupal chamber packed with frass, where they metamorphose into pupae between January and April (Burke 1921, p. 452). Approximately 1 month later, they metamorphose into an adult, although the adult form may remain in the cavity for several weeks (Burke 1921, p. 452). The adults chew through the outer bark and emerge in the spring or early summer through the exit hole, generally coinciding with the flowering season of the elderberry (Burke 1921, p. 450; Halstead and Oldham 1990, p. 23). Several studies or surveys have documented the presence of potential predators (e.g., earwigs, native and nonnative ants) of valley elderberry longhorn beetle larvae on elderberry shrubs or within stems (Barr 1991, p. 44; Huxel 2000, pp. 83-84; Holyoak and Graves 2010, pp. 16-17). The Argentine ant (Linepithema humile) is an invasive, nonnative species that has successfully colonized many areas of California (Vega and Rust 2001, p. 5), including permanent stream systems in parts of the Central Valley (Ward 1987, pp. 7-8; Huxel 2000, p. 84; Klasson et al. 2005, pp. 7-8). Nectar and honeydew are important food sources for Argentine ants, but studies of feeding behavior have found that Argentine ants are opportunistic feeders that readily forage on protein sources such as insect larvae or pupae, when available (Rust et al. 2000, p. 209). For example, Way et al. (1992, pp. 428-431) found that Argentine ants easily located and removed exposed eggs laid by another arboreal insect borer (Phoracantha semipunctata (Coleoptera: Cerambycidae)) in studies conducted in eucalyptus stands in Portugal. See Summary of Factors Affecting the Species section below for additional discussion of predation threats to the valley elderberry longhorn beetle. Collection records indicate that adult valley elderberry longhorn beetles can be observed from mid-March until early-June, though most records are from late-April to mid-May (Service 1984, p. 7). However, the adult stage is rare, both in space and time (Talley et al. 2006b, p. 649); adults likely die within 3 months (Halstead and Oldham 1990, p. 22). In a laboratory setting, Arnold (1984, p. 4) recorded females living up to 3 weeks, but males lived no more than 4 or 5 days. Similarly, Barr (1991, p. 46) described a life span of 17 days for a captive male and 25 days for two captive females. Halstead and Oldham (1990, p. 25) recorded caged adults living from 4 to 66 days in their experimental studies. The exit holes created in elderberry stems by the emerging adult eventually heal, but distinct scars remain on the plant stem (Talley et al. 2006a, p. 9). Although the presence of exit holes is used to survey and estimate population size for the valley elderberry longhorn beetle (Talley et al. 2006a, p. 10) (see additional discussion in Population Distribution section), this survey technique can be problematic as an estimate of occupancy for several reasons. First, the exit holes of both the valley elderberry longhorn beetle and the California elderberry longhorn beetle are reported to be identical and both beetles use the same elderberry taxa as their host plants (Arnold 2014b, pers. comm.), making it difficult to determine occupancy of the two subspecies in areas where their ranges may overlap. Second, surveys may have included observations of exit holes in dead stems, rather than only those found in live elderberry stems even though the species uses only live host plants. Third, once an elderberry stem is abandoned by the valley elderberry longhorn beetle, other species can occupy the holes and fill them with frass, making it difficult to confirm that the feeding chamber was created by the valley elderberry longhorn beetle (Talley et al. 2006a, p. 10). Finally, birds may also enlarge or rework valley elderberry longhorn beetle exit holes making them difficult to identify as such (Jones and Stokes Associates 1987, p. 38). Adult Behavior and Ecology Because of the species' rarity, its short-lived adult form, and difficulty in observing adults in the field, few studies document the behavior of adult valley elderberry longhorn beetles. Where observed, adults have been described as feeding on the nectar, flowers, and leaves of the elderberry plant (Arnold 1984, p. 4; Collinge et al. 2001, p. 105), or flying between trees (Service 1984, p. 7). Mating likely begins fairly quickly upon emergence. In field studies conducted in the north Sacramento area, Arnold (1984, p. 4) noted that male adult valley elderberry longhorn beetles appear more active than female adults, and males were observed taking short flights both within elderberry shrubs or to another shrub. Dispersal distances for the valley elderberry longhorn beetle are unknown. Based on site occupancy and patterns of colonization and extinction from 1991 to 1997, Collinge et al. (2001, p. 111) concluded that the valley elderberry longhorn beetle has limited dispersal ability. In this and following sections (i.e., Adult Behavior and Ecolo gy, Population Structure, and Summary under Background), the term "extinction" refers to the observations defined and described in the original citations (e.g., Collinge et al. 2001, entire, and Zisook 2007, entire), and does not refer to extinction of the valley elderberry longhorn beetle. Talley et al. (2007, p. 28) concluded the abundance of exit holes was spatially clustered over distances of 33 to 164 feet (ft) (10 to 50 meters (m)) in alluvial plain, riparian corridors, and upper riparian terrace habitats along portions of the American River Basin. In this same study, the average distance between the nearest neighboring (recent) exit hole was estimated at 141 ft (43 m); however, there was a wide range in the distances measured (plus or minus 144 ft (44 m)) (Talley et al. 2007, p. 28), making it difficult to draw definitive conclusions for this spatial relationship. Based on these data, Talley et al. (2007, p. 28) estimated the dispersal distance of an adult valley elderberry longhorn beetle from its emergent site to be 164 ft (50 m) or less (Talley et al. 2007, p. 28). However, Arnold (2014a, pers. comm.) has observed males flying at least 1 mile (mi) (1.6 kilometers (km)) in areas of good habitat. Given the varying results of these studies (i.e., Collinge et al. 2001; Talley et al. 2007; Arnold 2014a, pers. comm.) and lack of comprehensive studies of adult behaviors (e.g., mark and recapture studies), we are not able to accurately define a precise dispersal distance or assess how dispersal or other behaviors affect population persistence for this species. However, we believe that the dispersal ability for this species range is fairly limited. Habitat The valley elderberry longhorn beetle occupies portions of the Central Valley of California (also known as the Great Valley of California). The Central Valley is bounded by the Cascade Range to the north, the Sierra Nevada to the east, the Tehachapi Mountains to the south, and the coastal ranges and San Francisco Bay to the west. The valley is a large agricultural region drained by the Sacramento and San Joaquin Rivers and represents one of the more notable structural depressions in the world with much of the valley close to sea level in elevation with very low land surface relief, though elevations are higher along the valley margins (U.S. Geological Survey (USGS) 2013a). The climate in the Sacramento Valley and the San Joaquin Basin, which comprise the northern two-thirds of the Central Valley, can be characterized by cool, rainy winters and hot, dry summers (USGS 2013a). The average annual rainfall for the Central Valley ranges from 5 inches (12.7 centimeters (cm)) at the southern end to over 30 inches (76.2 cm) at the northern end (U.S. Bureau of Reclamation (USBR) 2014). With more than three-quarters of this rain coming during a 5-month period (December through April), seasonal floods are common in the valley due to heavy winter and spring runoffs. This precipitation pattern often creates water shortages in the summer and fall when rain is most needed for irrigation purposes; in low rainfall years, drought conditions are often observed in the valley (USBR 2014). In addition to rain falling within the valley itself, snowpack in the Sierra Nevada Mountains to the east historically provided flows from numerous rivers and streams into both the Sacramento Valley and the San Joaquin Valley through late spring (Katibah 1984, p. 24). These river systems have been altered by artificial levees, river channelization, dam construction, and water diversions (Katibah 1984, p. 28). The primary host plant of the valley elderberry longhorn beetle, blue elderberry, is an important component of riparian ecosystems in California (Vaghti et al. 2009, p. 28). As part of the remnant riparian forests in the Central Valley, elderberry provides wintering, foraging, and nesting habitat for birds (Gaines 1974, entire; Gaines 1980, entire) and supporting habitat for other boring insects and spiders (Barr 1991, p. 44). Its berries, leaves, and flowers provide food for wildlife, particularly during dry summer months (Vaghti et al. 2009, pp. 28-29). Elderberry seeds are likely dispersed by vertebrates, particularly birds (Talley 2005, p. 57). Elderberry seedlings have shallow roots, and high rates of mortality have been observed in the field (Talley 2005, p. 57). Lower seedling mortality rates (about 25 percent in the first year of planting) have been reported from areas where elderberry plants have been transplanted or where new elderberry seedlings have been planted (i.e., mitigation sites) where site conditions are managed (Holyoak et al. 2010, p. 48). A 1991 survey for the valley elderberry longhorn beetle between the Central Valley and adjacent foothills recorded elderberry plants (i.e., both red and blue elderberry) in habitats ranging from lowland riparian forest to foothill oak woodland, with elevation ranges from 60 to 2,260 ft (18.3 to 689 m) (Barr 1991, p. 37). Historically, the riparian forests in the Central Valley consisted of several canopy layers with a dense undergrowth and included Fremont cottonwood (Populus fremontii), California sycamore (Platanus racemosa), willows (Salix sp.), valley oak (Quercus lobata), box elder (Acer negundo var. californicum), Oregon ash (Fraxinus latifolia), and several species of vines (e.g., California grape (Vitis californica) and poison oak (Toxicodendron diversilobum)) (Service 1984, p. 6). These plant communities encompass several remaining natural and semi-natural floristic vegetation alliances and associations within the Great Valley Ecoregion of California (see Buck-Diaz et al. 2012, pp. 12-23). The 1991 survey conducted by Barr noted that elderberry was found most frequently in mixed plant communities, and in several types of habitat, including non-riparian locations, as both an understory and overstory plant (Barr 1991, pp. 40-41) with adults and exit holes created by the valley elderberry longhorn beetle found most commonly in riparian woodlands and savannas (Barr 1991, p. 41). Based on surveys completed along the Sacramento River, Gilbart (2009, p. 51) concluded that the valley elderberry longhorn beetle shows a preference for moderate amounts of cover, but that its occupancy is reduced with some canopy-producing plants, such as box elders, cottonwoods, and willows. Nonnative plants observed in vegetation communities containing elderberry include giant reed (Arundo donax), brome (Bromus spp.), and bur chervil (Anthriscus caucalis) (Vaghti et al. 2009, pp. 33-35). Black locust (Robinia pseudoacacia) and black walnut (Juglans hindsii) have been identified as important invasive species that can displace native plants in riparian floodplains in the Central Valley (Hunter 2000, p. 275; Vaghti et al. 2009, pp. 33-35) (see Summary of Factors Affecting the Species section below). Talley et al. (2006a, p. 10) stated that the valley elderberry longhorn beetle is found most frequently and most abundantly in areas that support significant riparian zones (see also Talley et al. 2007, discussed below). In a study to evaluate the occupancy of the valley elderberry longhorn beetle (based on exit hole observations) in roadside habitats in the northern Central Valley (2006-2008), Talley and Holyoak (2009, p. 8) found that site occupancy rates and rates of elderberry shrub occupancy within occupied sites were higher in riparian vegetation compared with non-riparian vegetation. Hydrological processes, specifically inundation duration and frequency, when measured by relative elevation above a river or creek floodplain, were found to significantly influence the distribution of elderberry in the lower alluvial reaches of the American River, Cache Creek, Cosumnes River, and Putah Creek (Talley 2005, pp. 52, 55, 66). The highest frequency of elderberry shrubs was found within an intermediate relative elevation gradient, that is, between areas influenced by flooding processes (low elevations) and water availability (higher elevations) (Talley 2005, pp. 45, 66). Talley (2005, pp. 56-58) also noted that the differences in relationships between elderberry abundance (number of shrubs within each elderberry patch), lateral size (shrub diameter), and stress level (proportion of dead stems per shrub) within the four river systems studied were attributed to stochastic (random) processes related to seed dispersal patterns and seedling mortality. Several studies have evaluated specific elderberry plant characteristics (e.g., size of stems, density of stems, and height above ground) relative to the valley elderberry longhorn beetle's life-history requirements and its abundance or presence (Jones and Stokes Associates 1987, pp. 27-32; Barr 1991, pp. 37-42; Collinge et al. 2001, pp. 107-109; Talley 2005, pp. 14-15, 17-19; Talley et al. 2007, entire; Holyoak and Koch-Munz 2008, entire). A detailed analysis of habitat and habitat quality for the valley elderberry longhorn beetle was completed based on surveys from 2002 to 2004 within one section of the American River Basin (American River Parkway) (Talley et al. 2007, entire). The study identified several predictors of habitat occupancy in the area surveyed and found that, in general, density of elderberry shrubs and shrub size, number of stems, and range of branch sizes were the most influential predictor variables (Talley et al. 2007, p. 30). Valley elderberry longhorn beetle exit holes were observed most frequently in elderberry stems or branches with a diameter of 0.8 to 2.76 inch (2 to 7 cm) and at a height of 0 to 3.28 ft (0 to 1 m) above ground, which may be the result of the size of the main stems of elderberry shrubs (Talley et al. 2007, p. 30). Of the four types of habitats evaluated within the study area, riparian cover types contained the greater quality of habitat, specifically upper riparian terrace and lower alluvial plain habitats (Talley et al. 2007, p. 30). There are limited studies on the relationship of the valley elderberry longhorn beetle's life-history features and those of its host plants, and the significance of this relationship to the ecology of riparian or other native plant communities where the species is found. Based on comprehensive surveys of elderberry taxa surveyed within the Central Valley in 1991, Barr (1991, p. 50) concluded that the presence of the valley elderberry longhorn beetle was not a factor in the health of elderberry host plants, nor were unhealthy host plants a factor determining the presence of the beetle. Gilbart (2009, entire) evaluated the relationship between the occupancy of the valley elderberry longhorn beetle and the health of blue elderberry planted at restoration sites along the Sacramento River (within the Sacramento River National Wildlife Refuge (NWR)). Results from this study found a correlation between occupancy and dead biomass (versus between occupancy and age), which supports results from other studies regarding the valley elderberry longhorn beetle's preference for plants with partial bark damage or that are otherwise stressed (e.g., low to moderate levels of damaged stems from pruning or burning), or for shrubs with, on average, 25 to 50 percent dead stems (Arnold 1984, p. 4; Holyoak and Koch-Munz 2008, pp. 447-448). Gilbart (2009, p. 54) stated that valley elderberry longhorn beetles likely use olfaction to locate host plants and mates, and volatiles released from the stressed tissue in elderberry shrubs are likely to be the initial cue used for host plant and mate location. This analysis also found that, although the exit holes created by the valley elderberry longhorn beetle may increase the dead biomass of elderberry shrubs, an increase in plant cover has a greater effect on dead biomass and is independent of the occupancy of the beetle (Gilbart 2009, pp. 53-54). Additional studies are needed to determine the relationships between the valley elderberry longhorn beetle's occupancy and: (1) The regenerative ability and timing of elderberry stem growth; (2) the beetle's observed preference for elderberry stems of a certain minimum diameter relative to the host plants' life history; and (3) other factors related to the ecological role of elderberry found in the species' range in the Central Valley. In an unpublished evaluation of environmental factors important to the valley elderberry longhorn beetle, Zisook (2007, entire) evaluated colonization and extinction events based on survey data from the Talley et al. (2007, entire) study along the American River Parkway. Zisook (2007, p. 5) found that colonization events were more likely to occur on shrubs located on north-facing slopes and on relatively large and previously occupied shrubs. Extinction events were more likely to be associated with relatively small elderberry shrubs, shrubs with stem damage, and in areas with larger floodplain widths (Zisook 2007, p. 5). In their evaluation of elderberry characteristics at mitigation sites compared with natural sites, Holyoak and Koch-Munz (2008, pp. 449-450) noted that, within mitigation sites, the abundance of the valley elderberry longhorn beetle per elderberry shrub was positively related to the size and age of the mitigation site, and the species was more likely to be present in elderberry shrubs with low levels of damage (e.g., partial bark damage) at these sites (see also discussion in Adult Behavior and Ecology section above). Relatedly, Talley et al. (2007, p. 28) found that the presence of recent exit holes was correlated with previous occupancy (that is, 73 percent of elderberry shrubs with recent holes also had old holes). A similar result was found in a 2010 survey effort, in which all but one watershed sampled had both new holes and old holes (in both dead and live wood) (Holyoak and Graves 2010, p. 12). Additional habitat characteristics relative to spatial relationships of elderberry shrubs and occupancy of the valley elderberry longhorn beetle are summarized in our metapopulation structure discussion (see Population Distribution section below). [*Federal RegisterVJ 2014-09-17] For more information about Targeted News Service products and services, please contact: Myron Struck, editor, Targeted News Service LLC, Springfield, Va., 703/304-1897; [email protected]; http://targetednews.com. TNS 22VistaJ-140917 gv-1175812 (c) 2014 Targeted News Service |