Saltcedar Trees Research Articles

Discovery of the genus Mirodryinus Ponomarenko, 1972 (Hymenoptera, Chrysidoidea, Dryinidae) associated with salt cedar trees in the eastern part of Iran

In 2015 and 2016 a survey was carried out on the parasitoids of leafhoppers (Hemiptera, Cicadomorpha) feeding on salt cedar trees (Tamarix spp.) growing around Hamoon Lake in the Sistan region (Iran). Among the collected material, a series of dryinid specimens belonging to Mirodryinus atlanticus Olmi, 1984 (Hymenoptera, Dryinidae, Bocchinae) was captured on branches of Tamarix aphylla (L.) Karst. and Tamarix stricta Boiss., infested by Opsius versicolor (Distant) (Hemiptera, Cicadellidae). The subfamily Bocchinae and the genus Mirodryinus Ponomarenko, 1972 are new records for Iran. Diagnostic characters and notes on the morphological variability of the newly collected specimens are presented and discussed.

Employing spatial information technologies to monitor biological control of saltcedar in West Texas

The saltcedar leaf beetle (Diorhadha spp.) has shown promise as a biocontrol agent for saltcedar (Tamarix spp.) invasions in the USA. In Texas, natural resource managers need assistance in monitoring biological control of invasive saltcedars. This study describes application of a medium-format, digital camera acquiring natural colour imagery and global positioning system (GPS) and geographic information system (GIS) technologies to check biological control of saltcedar in west Texas. On 8 July and 8 September 2011, natural colour airborne digital imagery was collected along a 155.8 km transect covering portions of Presidio and Brewster counties of Texas. The camera was tethered to a GPS receiver that geotagged each image and saved the coordinates to a key-hole marked up language file that was viewable on Google Earth. Saltcedar trees exhibiting severe feeding damage and those that were totally defoliated were easily identified in the imagery. The former appeared in orange to brown colour tones; the latter exhibited grey colour tones. Point distribution maps showing locations of saltcedar trees exhibiting feeding damage were developed from GPS information in the GIS. Coordinate points on the map were linked to the corresponding image, permitting the user to have quick access to view imagery. The results of this study show a practical method for monitoring biological control of saltcedar.

Applying broadband spectra to assess biological control of saltcedar in west Texas

Broadband field spectra were assessed to discriminate invasive saltcedar (Tamarix spp.) trees exhibiting feeding damage caused by the saltcedar leaf beetle (Diorhadba spp.) from other land cover types. Data were collected at two study sites near Presidio, Texas in 2010 and 2011. Spectral bands evaluated were coastal blue (400–450 nm), blue (450–510 nm), green (510–580 nm), yellow (585–625 nm), red (630–690 nm), red-edge (705–745 nm), and near-infrared (770–895, 860–1040 nm). Data were evaluated with analysis of variance and Scheffe’s multiple comparison test (α = 0.05). The red band generally separated severely damaged saltcedar trees from other land cover features. Near-infrared bands separated defoliated saltcedar trees. Broadband spectra has potential for distinguishing saltcedar trees exhibiting feeding damage caused by the saltcedar leaf beetle from other associated features, thus supporting future explorations of airborne and satellite-borne multispectral systems to monitor biological control of saltcedar within complex landscapes.

Population Metrics and Use of Saltcedar (Tamarix) Habitats by Common Side-Blotched Lizards (Uta stansburiana)

During 2009 and 2010, we observed common side-blotched lizards (Uta stansburiana) in two types of vegetation along the Virgin River in Nevada and Arizona: monotypic stands of nonnative saltcedars (Tamarix) and mixed stands of cottonwoods (Populus fremontii), willows (Salix gooddingii), mesquites (Prosopis), and saltcedar trees. Using mark-recapture techniques, parameters were recorded from 233 individual lizards. We detected no significant difference in parameters between monotypic stands of nonnative saltcedars and mixed vegetation. However, lizards selected habitats having a more open vegetative structure and parameters were correlated negatively with canopy cover. Greatest canopy cover occurred in sites having >65% stem counts for saltcedar trees. Our results suggest that common side-blotched lizards use habitats with similar structural characteristics in both mixed and nonnative vegetation, and that they avoid sites with dense canopy cover as in the densest stands of saltcedars.Durante 2009 y 2010, observamos las lagartijas costado manchado (Uta stansburiana) en dos tipos de vegetación a lo largo del río Virgin en Nevada y Arizona: rodales de cedro salado (Tamarix) no nativo y rodales mixtos de álamo (Populus fremontii), sauce (Salix gooddingii), mezquite (Prosopis), y cedro salado. Utilizando técnicas de marca-recaptura, obtuvimos parámetros poblacionales de 233 individuos. No encontramos ninguna diferencia significativa en los parámetros entre lugares dominados por el cedro salado y lugares con vegetación mixta. Sin embargo, las lagartijas seleccionaron hábitats que tienen una estructura de vegetación más abierta y los parámetros se correlacionaron negativamente con la cobertura del dosel vegetal. El dosel vegetal mayor fue encontrado en sitios donde >65% del conteo de tallos fue de cedro salado. Nuestros resultados sugieren que las lagartijas costado manchado utilizan hábitats con similares características estructurales tanto de vegetación mixta como de vegetación no nativa, y evitan sitios con un dosel vegetal denso, tales como se encuentran en rodales densos únicamente de cedro salado.

Field Evaluation ofDiorhabda elongateandD. carinata(Coleoptera: Chrysomelidae) for Biological Control of Saltcedars (Tamarixspp.) in Northwest Texas

Abstract. Four species of Diorhabda (Coleoptera: Chrysomelidae) have been approved for release as biological control agents of invasive saltcedars (Tamarix spp.) in the U.S. Two species, D. elongata (Brulle) and D. carinata (Faldermann), were evaluated for their ability to establish populations in northwest Texas (from 32.5°N to 34.0°N) and increase in numbers sufficient to defoliate saltcedar trees. Following releases of adults during 2 years, D. elongata overwintered, established, and increased sufficiently to defoliate saltcedar trees at all three release sites. In contrast, D. carinata overwintered in the field at only one of three sites and then only in very low numbers. D. carinata did not defoliate saltcedar trees outside of cages at any release site. After 2 years of release efforts, D. carinata could not be detected at any of the three release sites during the third year and was not considered to have established. Survival of overwintering adult D. carinata was significantly greater than survival...

Influence of Nutrient Levels inTamarixonDiorhabda sublineata(Coleoptera: Chrysomelidae) Survival and Fitness With Implications for Biological Control

Establishment of the saltcedar leaf beetle (Diorhabda spp.) has been unpredictable when caged or released in the field for saltcedar (Tamarix spp.) biocontrol. It has been observed that one caged tree might be voraciously fed upon by beetles while an adjacent tree in the cage is left untouched. We hypothesized that differences in the nutrient content of individual trees may explain this behavior. We evaluated survival, development rate, and egg production of beetles fed in the laboratory on saltcedar foliage from trees that had been grown under a range of fertilizer treatments. Tissue samples from the experimental trees and from the field were analyzed for percent nitrogen, phosphorus, and potassium. There was essentially no survival of beetle larvae fed foliage from saltcedar trees at nitrogen levels below 2.0%. At levels above 2.0% N, beetle larvae had corresponding increased survival rates and shorter development times. Multiple regression analyses indicated that nitrogen and phosphorus are important for larval survival and faster development rates. Higher levels of potassium were important for increased egg cluster production. The plant tissue analysis showed that the percentage of nitrogen in the experimental trees reflected the range of trees in the field and also that there is high variability within trees in the field. Our research indicates that if beetles are released on trees with poor nutrient quality, the larvae will not survive.

Early impacts of biological control on canopy cover and water use of the invasive saltcedar tree (Tamarix spp.) in western Nevada, USA

The success of biological control programs is rarely assessed beyond population level impacts on the target organism. The question of whether a biological control agent can either partially or completely restore ecosystem services independent of population level control is therefore still open to discussion. Using observational and experimental approaches, we investigated the ability of the saltcedar leaf beetle [Diorhabda carinulata (Brullé) (Coleoptera: Chrysomelidae)] to reduce the water use of saltcedar trees (Tamarix ramosissima Ledeb.) in two sites (Humboldt and Walker Rivers) in Nevada, USA. At these sites D. carinulata defoliated the majority of trees within 25 and 9 km, respectively, of the release location within 3 years. At the Humboldt site, D. carinulata reduced the canopy cover of trees adjacent to the release location by >90%. At a location 4 km away during the first year of defoliation, D. carinulata reduced peak (August) stem water use by 50-70% and stand transpiration (July to late September) by 75% (P = 0.052). There was, however, no reduction in stem water use and stand transpiration during the second year of defoliation due to reduced beetle abundances at that location. At the Walker site, we measured stand evapotranspiration (ET) in the center of a large saltcedar stand and found that ET was highest immediately prior to D. carinulata arrival, dropped dramatically with defoliation, and remained low through the subsequent 2 years of the study. In contrast, near the perimeter of the stand, D. carinulata did not reduce sap flow, partly because of low rates of defoliation but also because of increased water use per unit leaf area in response to defoliation. Taken together, our results provide evidence that in the early stages of population expansion D. carinulata can lead to substantial declines in saltcedar water use. The extent of these declines varies spatially and temporally and is dependent on saltcedar compensatory responses along with D. carinulata population dynamics and patterns of dispersal.

Arboreal Spider Ecology on Saltcedar (Tamarix) at Big Spring, Howard County, Texas

The arboreal species of spiders on saltcedar, Tamarix spp., at Big Spring, Howard County, TX, were surveyed to determine which species could pose a threat to the success of the biological control agent Diorhabda elongata (Brulle) (Coleoptera: Chrysomelidae). This resulted in a list of the spider genera and species found on tamarisk and some initial information on spider ecology in association with this weed tree. Of the 1,495 specimens of spiders collected above ground level during the 3 years of study at the site, 55 spider species in 15 families were found on saltcedar trees. The most abundant species of spiders were mapped to determine their habitat on the trees and in relation to other species. Orb-weavers (Araneidae) and jumping spiders (Salticidae) were the most diverse families, as well as being common, but mesh web-weavers (Dictynidae), while less diverse, were individually numerous. Only orb-weavers were observed to feed on D. elongata in the field.

A Modified Sampling Method to Capture Arboreal Arthropods

Abstract. Arthropods were sampled from branches of saltcedar, Tamarix spp., and willow trees, Salix spp. using a new funnel bucket technique. This is a modification of the beat-bucket design. The funnel bucket was compared to results found by using a traditional 5-gallon bucket, sweep net, and beat sheet. Each method was assessed for effectiveness of arthropod capture. Sixteen saltcedar trees and 16 willow trees were sampled with each method for 10 seconds per compass side of the tree. The means, standard errors, and n needed for a 90% confidence interval are provided for each technique. The funnel bucket method collected numbers of arthropods comparable to the other sampling techniques tested. This technique may be another option for sampling in trees and shrubs, especially for arthropod predators.

Lack of Establishment of the Mediterranean Tamarisk Beetle Diorhabda elongate (Coleoptera: Chrysomelidae) on Athel (Tamarix aphylla) (Tamaricaceae) in South Texas1

Adult Mediterranean tamarisk beetles, Diorhabda elongate (Brullé), a defoliator of exotic saltcedar (Tamarix spp.), were released into four field cages containing small saltcedar trees or closely-related exotic athel trees (Tamarix aphylla (L.) Karsten) and onto uncaged beneficial mature athel trees at sites in south Texas. In field cages, egg, larval, and adult densities per meter of green foliage were equal on saltcedar and athel in the first 8 weeks after release, but numbers of eggs, larvae, and adults were at least two-fold more on saltcedar. During this time, the beetles reduced green foliage by 50% on athel and by 20% on saltcedar. However, athel green foliage recovered after 10 weeks, while saltcedar foliage continued to decline. At two roadside field sites containing mature athel and no saltcedar, D. elongata adults were released in bagged athel branches in July 2006 and May 2007 and produced larvae that defoliated the branches by the third week after infestation. A few larvae and adults were found on unbagged athel branches during the first 3 months after release, but beetles failed to become established on athel trees and removed no more than 3% of green foliage from athel branches, which remained >85% green for 2 years. The Mediterranean tamarisk beetle thus did not colonize or cause permanent disfiguring damage to athel trees.

'Candidatus Phytoplasma tamaricis', a novel taxon discovered in witches'-broom-diseased salt cedar (Tamarix chinensis Lour.)

Salt cedar trees with pronounced witches'-broom symptoms were observed in their natural habitat in China. 16S rRNA gene sequences unique to phytoplasmas were detected in every DNA sample extracted from stem and leaf tissues of the symptomatic trees, revealing a direct association between phytoplasma infection and the salt cedar witches'-broom (SCWB) disease. Phylogenetic analysis of the SCWB phytoplasma 16S rRNA gene sequence indicated that the SCWB phytoplasma belonged to a subclade consisting of several mutually distinct 'Candidatus Phytoplasma' taxa including 'Ca. Phytoplasma prunorum', 'Ca. Phytoplasma mali', 'Ca. Phytoplasma pyri' and 'Ca. Phytoplasma spartii'. Pairwise sequence similarity scores calculated from an alignment of near full-length 16S rRNA genes revealed that SCWB phytoplasma shared 96.6 % or less sequence similarity with each previously described or proposed 'Ca. Phytoplasma' taxon, justifying the recognition of SCWB phytoplasma as a novel taxon, 'Candidatus Phytoplasma tamaricis'. The distinct virtual RFLP pattern derived from the SCWB phytoplasma 16S rRNA gene sequence, together with its lower-than-threshold similarity coefficient values with RFLP patterns of any of the 29 previously established groups, supported the recognition of a new 16Sr group, designated 16SrXXX, salt cedar witches'-broom phytoplasma group.

Open field host selection and behavior by tamarisk beetles ( Diorhabda spp.) (Coleoptera: Chrysomelidae) in biological control of exotic saltcedars ( Tamarix spp.) and risks to non-target athel ( T. aphylla) and native Frankenia spp.

Biological control of invasive saltcedars ( Tamarix spp.) in the western U.S. by exotic tamarisk leaf beetles, Diorhabda spp., first released in 2001 after 15 years of development, has been successful. In Texas, beetles from Crete, Greece were first released in 2004 and are providing control. However, adults alight, feed and oviposit on athel ( Tamarix aphylla), an evergreen tree used for shade and as a windbreak in the southwestern U.S. and México, and occasionally feed on native Frankenia spp. plants. The ability of tamarisk beetles to establish on these potential field hosts was investigated in the field. In no-choice tests in bagged branches, beetle species from Crete and Sfax, Tunisia produced 30–45% as many egg masses and 40–60% as many larvae on athel as on saltcedar. In uncaged choice tests in south Texas, adult, egg mass and larval densities were 10-fold higher on saltcedar than on adjacent athel trees after 2 weeks, and damage by the beetles was 2- to 10-fold greater on saltcedar. At a site near Big Spring, in west-central Texas, adults, egg masses and 1st and 2nd instar larvae were 2- to 8-fold more abundant on saltcedar than on athel planted within a mature saltcedar stand being defoliated by Crete beetles, and beetles were 200-fold or less abundant or not found at all on Frankenia. At a site near Lovelock, Nevada, damage by beetles of a species collected from Fukang, China was 12–78% higher on saltcedar than on athel planted among mature saltcedar trees undergoing defoliation. The results demonstrate that 50–90% reduced oviposition on athel and beetle dispersal patterns within resident saltcedar limit the ability of Diorhabda spp. to establish populations and have impact on athel in the field.

Consumptive Use and Water Waste by Phreatophytes

Phreatophytes are vigorous, water-loving plants ranging from small natural vegetation to large saltcedar and cottonwood trees; saltcedar and cottonwoods use from 50 to 100% more water than most agricultural crops; in California and New Mexico about 25 to 50% of consumptive use by these plants may be saved by elimination of saltcedar and cottonwoods.