Biological Control Of Yellow Starthistle Research Articles

Synchytrium solstitiale: reclassification based on the function and role of resting spores

Studies were made about resting spores of Synchytrium solstitiale, a chytrid that causes false rust disease of yellow starthistle (YST). During evaluation of this fungus for biological control of YST, a protocol for resting spore germination was developed. Details of resting spore germination and study of long-term survival of the fungus were documented. Resting spores from dried leaves germinated after incubating them on water agar at least 7 d at 10–15 C. Resting spores were viable after storage in air-dried leaves more than 2 y at room temperature, suggesting they have a role in off-season and long-term survival of the fungus. Each resting spore produced a single sorus that contained a single sporangium, which on germination released zoospores through a pore. YST inoculated with germinated resting spores developed symptoms typical of false rust disease. All spore forms of S. solstitiale have been found to be functional, and the life cycle of S. solstitiale has been completed under controlled laboratory and greenhouse conditions. Resting spore galls differ from sporangial galls both morphologically and biologically, and in comparison, each sporangial gall cleaves into several sori and each sorus produces 5–25 sporangia that rupture during release of zoospores. For this reason S. solstitiale should be reclassified as diheterogallic sensu Karling (Am J Bot 42:540–545). Because resting spores function as prosori and produce an external sorus, S. solstitiale is best placed in into the subgenus Exosynchytrium.

Climatic analysis to determine where to collect and release Puccinia jaceae var. solstitialis for biological control of yellow starthistle

Puccinia jaceae var. solstitialis is an autoecious rust fungus that is native to areas of Afro-Eurasia with a Mediterranean climate. An isolate collected near Sivas, Turkey was released for classical biological control of yellow starthistle (YST), which is an invasive alien weed in California, USA. The fungus has been released throughout California, but long-term establishment rates are generally low, apparently because this ecotype is not well adapted to the climate where the weed is most invasive. Using a site with excellent establishment as a target, the Match Climates function in CLIMEX climate modeling software identified similar sites in and around the San Francisco Bay Area, east to the Central Valley and Sierra foothills, and along the coast of Southern California. Similar sites in other states include Walla Walla, Washington, Pendelton, Oregon and Salt Lake City, Utah. A Compare Locations model based primarily on experimentally measured temperature and humidity requirements of the rust produced similar results. Using Sacramento, California, which is in the center of YST distribution, as a target, the Match Climates function predicted that the best locations to search for rust accessions to use in California are near Tunis, Tunisia, Foggia, Italy, Khalkis, Greece, Kayseri, Turkey, and possibly Constantine, Algeria. This generally agrees with the prediction of a Compare Locations model based on the geographic distribution of YST in California. Climatic factors that limit the long-term establishment of the fungus are likely to be summer heat and/or dry stress and short dew periods.

DNA Fingerprinting to Improve Data Collection Efficiency and Yield in an Open-Field Host-Specificity Test of a Weed Biological Control Candidate

AbstractAn open-field test was conducted in southern France to assess the host-specificity of Ceratapion basicorne (Illiger), a candidate for biological control of yellow starthistle. Test plants were infested by naturally occurring populations of C. basicorne but were also exposed to sympatric herbivore species, including other Ceratapion spp. Insects from the test plants were collected directly into tubes of ethanol and were subsequently identified to species according to DNA sequence similarity with morphologically identified reference specimens. This integrated, morphological and molecular identification method was used in an effort to maximize the amount of data gained in the field bioassay and to minimize the number of taxonomist–hours necessary to complete the study. The results obtained showed that the French C. basicorne population only attacked yellow starthistle and cornflower, another known host of C. basicorne. Molecular phylogenetic analysis of the insects collected from all other nonhost plants rejected the possibility that any were C. basicorne.

Establishment of the Yellow Starthistle Rust in California: Release, Recovery, and Spread.

The rust fungus Puccinia jaceae var. solstitialis is the first pathogen released for biological control of yellow starthistle (Centaurea solstitialis). From 2004 to 2006, the pathogen was released at 176 sites in 40 counties throughout the state of California. Release sites were evaluated 1 to 3 months and 1, 2, and, in some cases, 3 years after releases to monitor for reemergence. At 1 to 3 months after inoculation, 58 to 93% of sites had rust infection, depending on the year. After 1, 2, and 3 years, the percentages declined to 19 to 21, 9 to 10, and 3% respectively. Spread was detected at 19% of the sites with rust infection, with an average distance of 21 m (±13.3 standard error). The greatest spread occurred at a site in Sonoma County. At this site, the rust spread to over 37 acres 1 year after it was released and has remained in this area for three seasons. Reemergence 1 and 2 years after inoculations was more likely in Northern (above 40°N) compared with Southern California (below 36°N). In general, reemergence was more likely at lower elevations when release sites were within 150 km of the coast. Overall, the rust has not demonstrated a strong record of persistence based on these observations.

Effects of the rust Puccinia jaceae var. solstitialis on Centaurea solstitialis (yellow starthistle) growth and competition

The rust fungus Puccinia jaceae var. solstitialis was introduced to California in 2003 for biological control of yellow starthistle ( Centaurea solstitialis). To test its effectiveness under field conditions, we examined biomass production, chlorophyll levels, and seedhead production of yellow starthistle (YST) infected with P. jaceae. We also evaluated the effect of P. jaceae on the competitive ability of YST grown with wild oat ( Avena fatua), a widespread winter annual grass commonly associated with YST infestations. Chlorophyll levels were reduced by over 50% in severely rust-infested YST leaves. P. jaceae had no effect on growth or reproductive variables in monoculture plots, but caused a modest reduction in YST performance in the competition experiment. In this study, infected plants had fewer leaves than uninfected plants and slightly reduced rosette diameters. P. jaceae also decreased YST biomass from 3.18 kg m −2 in non-inoculated competition plots to 2.62 kg m −2 in inoculated plots over both years of the experiment. Although not significant, there was a trend towards reduced seedhead production in the inoculated plots. These results indicate that P. jaceae may have some negative effects on YST growth, especially under conditions of interspecific competition. However, the effects of P. jaceae appear to be of minor biological significance and are unlikely to cause major declines in YST populations statewide.

Susceptibility of yellow starthistle to Pucciniajaceae var. solstitialis and greenhouse production of inoculum for classical biological control programs

In anticipation of large-scale distribution of a Turkish isolate of Puccinia jaceae var. solstitialis in California for biological control of yellow starthistle ( Centaurea solstitialis, YST), susceptibility of YST within the state was determined and a protocol for bulk inoculum production was developed. Inoculation was made of 62 field accessions of YST representative of the range of habitats in California. These were determined to be equally susceptible to infection by the isolate approved for release in the United States in 2003. To support a program to speed establishment by release at many locations statewide, protocols for artificial increase of inoculum were developed. Over 64 g of urediniospores were produced with a mass-production system under greenhouse conditions from 2003 to 2006. Yield of inoculum varied by season, with peak production occurring from early spring through early summer. A large-scale urediniospore harvest also was made from a field plot at Davis, California. Our results show that susceptibility of YST in California is not likely to limit establishment of P. jaceae for biological control, and that production of this or other obligate pathogenic fungi (biological control agent) is possible for support of statewide release and research programs.

Non-target plant use by a weed biocontrol agent in idaho: host expansion or opportunistic behavior?

Larinus curtus Hochhuth (Coleoptera: Curculionidae) was first introduced into the western United States from Greece for the biological control of yellow starthistle (YST), Centaurea solstitialis L., in 1992. The discovery of L. curtus adults in the open flowerheads of safflower (SF), Carthamus tinctorius L., near Lewiston, Idaho in 2007 suggested this weevil might be expanding its host range to include a non-target crop species closely related to YST. In 2008 field plots near the 2007 observation site, 92 L. curtus adults fed in open SF flowerheads (pollen feeding and minor feeding on corolla tubes). No eggs were found in the ovarioles of 19 pollen-feeding females. No eggs, larvae, or evidence of larval feeding were detected in 39 tagged SF capitula, and no adults emerged from approximately 7,135 post-flowering SF capitula. These collective results are not indicative of an expanding developmental host-range of L. curtus. Also, they are consistent with pre-release host-specificity test results.

Puccinia jaceae var. solstitialis Teliospore Priming on Yellow Starthistle

Following the introduction of Puccinia jaceae var. solstitialis to California for biological control of yellow starthistle (Centaurea solstitialis, Asteraceae), teliospores, pycnia, and multiple urediniospore generations have been observed in the field. Because urediniospores have a relatively short life span in the field, functioning teliospores are expected to be necessary for the permanent establishment of P. jaceae var. solstitialis in California. To determine if conditions in California were conducive to this, teliospore emergence and priming were evaluated in the field. A factorial experiment in the laboratory with five incubation times and three incubation temperatures was used to determine teliospore priming requirements. Teliospore production coincided with plant senescence in August and September at two sites in 2 years; fewer teliospores were produced in 2006, suggesting inconsistent teliospore production may limit population growth and contribute to local extinctions in some areas. When teliospores were primed in the field, germination was low through the fall and abruptly peaked in January during both years. In the laboratory, teliospore germination increased as incubation time increased from 2 to 6 weeks and temperatures decreased from 12 to 4 degrees C. A degree-hour model derived from laboratory data accurately predicts when teliospores are primed for germination in the field. Based on the results obtained in this study, it is apparent that teliospore germination can occur over a range of priming conditions. However, lower temperatures and longer incubation periods are superior in breaking teliospore dormancy.

Latent period and viability of Puccinia jaceae var. solstitialis urediniospores: Implications for biological control of yellow starthistle

Since the introduction of Puccinia jaceae var. solstitialis into California in 2003, multiple urediniospore generations have been observed, along with teliospores and pycnia, on yellow starthistle (Centaurea solstitialis). A field and laboratory study of urediniospore viability was conducted to determine the potential of using infected plant material for redistribution of inoculum into new areas. To better understand the life history of P. j. solstitialis, urediniospore viability was measured during the summer and fall when the host plant is usually senescent. Latent period (time from inoculation to pustule eruption) after field and laboratory inoculations was measured in order to determine the potential number of urediniospore generations that occur per year. Viability of urediniospores stored in the laboratory gradually declined over a period of 10 weeks; spore hydration increased germination. Based on the results obtained in this study, introductions of harvested infected plant material would have to be done quickly to offset losses in urediniospore viability. Urediniospore viability in the field decreased exponentially 86% near the coast and 97% in the Central Valley three weeks after production, and was negligible (0–0.2%) thereafter. Latent period ranged from four to five weeks at cool winter temperatures to two to three weeks at warm summer temperatures in both the laboratory and field. Results of this study suggest that urediniospores are not likely to remain viable through the summer and fall dry season. Teliospores, therefore, serve as the inoculum source when YST seedlings germinate in the winter. Approximately six urediniospore generations can be expected to occur each year in central-northern California under suitable conditions for disease.

First Report of Puccinia jaceae var. solstitialis Pycnia on Yellow Starthistle in the United States.

The rust fungus Puccinia jaceae (Otth) var. solstitialis field isolate FDWSRU 84-71 (formerly TR 84-96) was first released in California for the biological control of yellow starthistle (YST; Centaurea solstitialis) in July 2003. This isolate was collected by S. S. Rosenthal in 1984, east of Yarhisar and Hafik (SIVAS), Turkey. It is macrocyclic and autoecious (1), completing its entire life cycle on YST. Observations were made in field plots west of Woodland, CA that had been inoculated on a monthly regimen between January and June of 2005. On February 22 and March 2, 2006, pycnia were observed in and around one of the plots (38°42.767'N, 121°53.732'W at an altitude of 57 m). Pycnia were yellow, flask shaped, and small (less than 100 μm in diameter), occurring in clusters on abaxial leaf surfaces or on petioles. DNA was isolated from pycnial and uredinial samples collected from the site and used for polymerase chain reaction amplification of the ITS2 region with P. jaceae specific primers. Sequences of amplicons from both samples were identical to FDWSRU 84-71 (GenBank Accession No. AF047728). Further amplification of pycnial DNA with PCR primers specific to the released P. jaceae isolate (2) produced the expected 851-bp amplicon. To our knowledge, this is the first report of pycnia from Puccinia jaceae var. solstitialis in the United States, suggesting that the YST rust is fully functional and completes its life cycle in California.

Supplemental risk evaluations of Puccinia jaceae var. solstitialis for biological control of yellow starthistle

Abstract Additional tests of native North American Cirsium species, Saussurea americana , and modern safflower cultivars ( Carthamus tinctorius ) were requested by regulators and specific interest groups during the risk assessment of foreign isolates of Puccinia jaceae var. solstitialis for biological control of yellow starthistle (YST, Centaurea solstitialis ) in the United States. These tests supplement an earlier, extensive host range determination that established P. jaceae from YST as generally host specific and potentially useful for biological control. The additional research was in response to potential hazards identified in an earlier study, changes in safflower cultivars, and concern that P. jaceae might cause a safflower seedling disease similar to hypocotyl infections from infestation by Puccinia carthami teliospores. S. americana , a close relative of yellow starthistle, had not been tested previously. All tests were conducted in a containment greenhouse. Foliage of 19 Cirsium species, 11 safflower cultivars, and S. americana was inoculated with urediniospores and subjected to a 16-h dew period at 18–20 °C. Neither the Cirsium species nor S. americana became infected after foliar inoculations. Compared to foliar infections by P. carthami from safflower in California, only minor infections developed from inoculations with P. jaceae . These were similar to infections observed in earlier studies, and it was not possible to maintain P. jaceae under optimal greenhouse conditions on safflower foliage. Quantitative teliospore inoculations with P. jaceae did not cause infection on safflower hypocotyls, even though large cankers occurred on plants inoculated with P. carthami teliospores. Clear microscopic evidence of infection also was observed in hypocotyls inoculated with P. carthami . These data suggest that native (including rare, threatened, or endangered) Cirsium spp., modern safflower cultivars, and S. americana are not likely to be adversely affected by the use of P. jaceae for biological control of YST. Results from these studies substantiate previous findings and were incorporated in a proposal for permission to use P. jaceae for YST control in California.

Evaluating biological control of yellow starthistle (Centaurea solstitialis) in California: A GIS based supply–demand demographic model

The biological control of yellow starthistle (Centaurea solstitialis) by four capitulum-feeding insects (weevils Bangasternus orientalis and Eustenopus villosus, and flies Urophora sirunaseva and Chaetorellia succinea), as affected by plant competition with annual grasses, is analyzed using a weather-driven, physiologically based, age-structured, simulation model. Seed density in the soil seed bank for yellow starthistle and the number of overwintering insects provide between-season links. Seed germination intensity and pattern is determined by the timing and quantity of autumn rains and temperatures, while season-length is mostly determined by soil–water balance. Output from the yellow starthistle systems model was integrated into a geographic information system to examine regional differences in abundance for all species across several ecological zones of California. A marginal analysis of the simulation results was performed to examine the efficacy of each capitulum-feeding insect, their within-capitulum competitive interactions, and the effect of competition from annual grasses on yellow starthistle populations. The model suggests that lack of complete control of yellow starthistle may be due to plant compensation via increased per-plant seed production at lower plant densities and the incomplete destruction of seed in attacked capitula. The model suggests herbivory that reduces the plant’s ability to compensate and/or kills whole plants before seed maturity would most likely lead to control of yellow starthistle.

Factors Affecting Germination of Puccinia jaceae var. solstitialis Teliospores from Yellow Starthistle

ABSTRACT The rust fungus Puccinia jaceae var. solstitialis is a candidate for biological control of yellow starthistle (YST). Part of the risk assessment includes determining if safflower seedlings are susceptible to infection by teliospores of P. jaceae. A protocol for germination of P. jaceae teliospores is needed to verify that teliospores used in comparative studies are viable. The protocol developed from this research has two steps: first, priming teliospores on water agar at 4 degrees C in the dark, and second, incubating them at warmer temperatures for 1 week in the presence of an exogenous stimulator. Priming longer than 4 weeks resulted in significantly greater germination than priming for shorter periods. Sources of effective stimulator included seeds and seedlings of YST or safflower. The greatest germination occurred during incubation at 18 degrees C in the dark. Teliospore germination was reduced after incubation with a 12- or 14-h photoperiod. A low percentage (<20%) of teliospores of two isolates germinated after 44 and 96 weeks of dry storage at room temperature; samples of each isolate tested after that did not germinate. Data indicate teliospores of several isolates of P. jaceae are viable, and the protocol will be used to prepare teliospores of P. jaceae for comparative studies with P. carthami on safflower seedlings.

Chaetorellia australis(Diptera: Tephritidae) for biological control of yellow starthistle,Centaurea solstitialis(Compositae), in the western USA: establishment and seed destruction

AbstractYellow starthistle (Centaurea solstitialisLinnaeus) (Compositae), native to Eurasia and the Mediterranean Basin, is a spiny and poisonous, naturalized, invasive weed of grasslands and other environments in the western USA.Chaetorellia australisHering is a trivoltine natural enemy of yellow starthistle whose larvae feed on developing seeds within capitula. Following host-specificity studies in Greece and the USA,C. australiswas first introduced from Greece into the USA in 1988 for the biological control of yellow starthistle. Field samples of yellow starthistle capitula revealed that 10.3% (four years after initial release) and 18.0% (three years after initial release) of capitula at Colfax, Washington, and Merlin, Oregon, respectively, were infested by ≥ 1C. australis(mature larvae or empty puparia). Both sites also contained naturalized, weedy populations of,Centaurea cyanus, a second host-plant ofChaetorellia australis. The fly was also recovered fromCentaurea cyanuscapitula two years after its release at Kendrick, Idaho. The potential importance of the presence ofC. cyanusforChaetorellia australisand biological control of yellow starthistle is discussed. At the Colfax site, all infested yellow starthistle capitula contained 1C. australis, while at the Merlin site 28.8% of infested capitula contained &gt; 1C. australis, with a mean of 1.36C. australisper infested capitulum. A preliminary seed destruction impact study at the Merlin site showed that there was a 83.4% reduction in seeds per capitulum infested by ≥ 1C. australis, and the presence of &gt; 1C. australisresulted in a 95.4% reduction in seeds per infested capitulum.

Life History of Eustenopus villosus (Coleoptera: Curculionidae), a Promising Biological Control Agent for Yellow Starthistle

Studies on the biology and host specificity of Eustenopus villosus (Boheman) were carried out in the field and laboratory in Greece and in the laboratory in Italy from 1981 to 1990. The weevil was first released in the United States for biological control of yellow starthistle, Centaurea solstitialis L. (Asteraceae: Cardueae), during 1990. In nature, overwintering adults appeared on bolting yellow starthistle plants by mid-May and were found until mid-July, south of Thessaloniki, Greece. Oviposition started at the beginning of June and the first pupae were found in early July. The first adults of the F1 generation were found about mid-July in field-collected seedheads. Adults started to emerge gradually from seedheads from mid-July to the end of August and hibernated in cracks in the soil and among debris on the soil surface. E. villosus is univoltine and had three instars under laboratory conditions. Mating and feeding behavior, fecundity, and mortality are described. Adults fed on meristematic tissue and caused severe damage to the plants, and larvae fed in developing seedheads and reduced seed production up to 100% in infested seedheads. Because there is up to 97% mortality of the immature stages, the weevil does not build up dense populations in its native area.

Life history and host specificity of Urophora sirunaseva (Hering) (Dipt., Tephritidae), a candidate for biological control of yellow starthistle, with remarks on the host plant

AbstractYellow starthistle (YST) is an annual (occasionally biennial) weed that is a major problem in many parts of the USA. Seeds of YST collected in various locations in the USA and Europe were grown in Greece under the same conditions. No significant morphological differences could be found among the plants, and all were annuals. Larvae of the southern European picture‐winged fly, Urophora sirunaseva (Hering) (Dipt., Tephritidae), a species introduced and established in the western USA as a biological control agent, feed only in the seedheads of YST. Urophora sirunaseva is bivoltine and overwinters as mature larvae in seedheads. Adults of the overwintered generation emerged from late April to late May, and the F‐1 generation, from mid June to mid July. Adults copulated frequently throughout their lives and oviposition began within four to six days after emergence of the females. Females lived up to 36 days and each laid up to 270 eggs. Eggs were deposited between single florettes in young buds, and hatched within nine to ten days. The development of the immature stages (egg to adult) required 25–26 days under semi‐natural conditions. Larval and pupal mortality was about 50 %. The rate of infestation of YST seedheads was very patchy in several populations of YST.ZusammenfassungZur Biologie und Wirtsspezifität von Urophora sirunaseva (Hering) (Dipt., Tephritidae), einem möglichen Kandidaten zur biologischen Bekämpfung von gelben Sterndisteln, mit Bemerkungen über die WirtspflanzeCentaurea solstitialis ist ein‐, gelegentlich zweijähriges Unkraut. Die Pflanze wurde von Eurasien nach Nordamerika verschleppt und verursacht dort enorme Probleme. Samen von verschiedenen Lokalitäten in den USA und in Europa wurden unter gleichen Bedingungen in Griechenland angesät. Dort entwickelten sich alle Pflanzen als Einjährige. Urophora sirunaseva (Dipt., Tephritidae) ist monophag und entwickelt sich nur in C. solstitialis. Die Art hat zwei Generationen und überwintert als erwachsene Larven in den Blütenköpfen. Die Adulten schlüpfen vom späten April bis späten Mai, und die F1‐Generation schlüpft von Mitte Juni bis Mitte Juli. Die Adulten kopulieren sehr oft bis zum Ende ihres Lebens. Die Eiablage beginnt 4–6 Tage nach dem Schlüpfen. Die Weibchen lebten im Experiment bis zu 36 Tagen und legten bis 270 Eier pro Weibchen. Die Eier wurden zwischen den Röhrenblüten der jungen Knospen abgelegt und schlüpften nach 9–10 Tagen. Die Entwicklung vom Ei bis zum Adultenstadium dauerte 25–26 Tage. Die Larven‐ und Puppenmortalität betrug 42–76 Prozent. Die Art wurde für die biologische Bekämpfung von C. solstitialis in den USA (Kalifornia, Idaho, und Washington) angesiedelt.

A contribution to the biology, phenology and host specificity of Chaetorellia hexachaeta Loew (Dipt., Tephritidae), a possible candidate for the biological control of yellow starthistle (Centautea solstitialis L.)

AbstractThe biology and host specificity of the tephritid Chaetorellia hexachaeta Loew, the larvae of which live in the flower heads of Centaurea solstitialis and some related Centaurea spp. was studied in Northern Greece. The species has at least three generations per year. Previous research revealed that under laboratory conditions adults lived up to 60 days and up to 243 eggs were deposited by a female. Under cage conditions, particularly under oviposition pressure, the threshold of acceptance was lowered and eggs were laid into the flower heads of several non‐host plants. However, the larvae did not survive on 3 non‐hosts tested (Cirsium spp., Zinnia elegans). When caged with safflower (Carthamus tinctorius) and yellow starthistle heads (two—choice test), adults showed a 100% preference for yellow starthistle (YST). On the average, a single larva destroys 86.3% of the achenes of the attacked YST flower head. The species is recommended for consideration as a candidate for the biological control of Centaurea solstitialis but additional host specificity studies are needed before a definitive decision as to its introduction to North America can be made.ZusammenfassungEin Beitrag zur Biologie, Phänologie und Wirtsspezifität von Chaetorellia hexachaeta Loew (Dipt., Tephritidae) und ihre potentielle Eignung für die biologische Bekämpfung von Centaurea solstitialisDie Bohrfliege Chaetorellia hexachaeta Loew ist in Nordgriechenland, wo sie in 3 oder mehr Generationen jährlich auftreten kann, eine wichtige Art im Phytophagenkomplex von Centaurea solstitialis. Im Freiland ist ihr Wirtskreis auf einige zumeist nah verwandte Centaurea‐Arten beschränkt. Im Labor lebten die adulten Tiere bis zu 60 Tage und legten bis zu 243 Eier/Weibchen. Die Eiablage erfolgt unter die Brakteen der Wirtspflanze. In Labortests konnte auch an verschiedenen, nicht zum Wirtskreis der Art gehörenden, Compositen eine Eiablage induziert werden, jedoch waren die Larven nicht in der Lage, sich in den drei eingehender untersuchten Testpflanzen (Cirsium creticum, C. vulgare und Zinnia elegans) zu entwickeln. Es konnte gezeigt werden, daß das Fehlen geeigneter Wirtspflanzen die Akzeptanzschwelle der Weibchen senkt und zur Eiablage in “Nicht‐Wirten” führen kann. Im Durchschnitt zerstört eine einzige C. hexachaeta‐Larve über 80% der Achanenproduktion eines Centaurea solstitialis‐Blütenkopfes. Im Zweifach‐Wahlversuch bevorzugen die Weibchen zu 100% ihre Wirtspflanze gegenüber Carthamus tinctorius. Damit sprechen die biologischen Befunde sowie die Ergebnisse unserer Versuche zur Wirtsspezifität dafür, diese Art zur biologischen Bekämpfung von Centaurea solstitialis einzusetzen, jedoch sind noch weitere Sicher‐heitstests notwendig, bevor über eine Einfuhr dieser Art nach Nordamerika entschieden werden kann.