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

1996 ◽  
Vol 86 (2) ◽  
pp. 177-182 ◽  
Author(s):  
C.E. Turner ◽  
G.L. Piper ◽  
E.M. Coombs
Keyword(s):  
Biological Control ◽  
Centaurea Solstitialis ◽  
Yellow Starthistle ◽  
Invasive Weed ◽  
Western Usa ◽  
Centaurea Cyanus ◽  
Field Samples ◽  
Initial Release ◽  
The Usa ◽  
Chaetorellia Australis

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 > 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 > 1C. australisresulted in a 95.4% reduction in seeds per infested capitulum.

scholarly journals Factors Affecting Infection of Yellow Starthistle (Centaurea solstitialis) by Synchytrium solstitiale, Causal Agent of False Rust Disease

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 425-428 ◽  
Author(s):  
T. L. Widmer ◽  
F. Guermache
Keyword(s):  
United States ◽  
Classical Biological Control ◽  
The United States ◽  
Carthamus Tinctorius ◽  
Centaurea Solstitialis ◽  
Yellow Starthistle ◽  
Rust Disease ◽  
Invasive Weed ◽  
Factors Affecting ◽  
Centaurea Calcitrapa

Yellow starthistle (Centaurea solstitialis) is an annual invasive weed in the United States with Mediterranean origins. The expense of chemical control and the vast area of invasion make this weed an appropriate target for classical biological control. Observations of a field site in southern France revealed small orange galls on the leaves of yellow starthistle seedlings caused by the fungus Synchytrium solstitiale. Inoculation of yellow starthistle seedlings with a suspension of zoospores released from infected tissue resulted in infection. Ten days after inoculation, typical orange galls appeared on the exposed tissue. Preliminary host range testing showed up to 100% infection of C. solstitialis seedlings from both France and the United States and infection of Carthamus tinctorius, Centaurea americana, C. diffusa, C. rothrockii, C. squarrosa, and Helianthus annuus seedlings. No symptoms were observed on seedlings of Centaurea calcitrapa, C. maculosa, C. sulfurea, Cirsium californica, C. occidentale, Cynera cardunculus, and Taraxacum officinale. Zoospores were released in a pH range between 4.45 and 8.25 and optimally at temperatures between 5 and 15°C. Infection of yellow starthistle seedlings occurred after a minimum 1-h exposure to a zoospore suspension at 20°C.

Biological Control of Yellow Starthistle (Centaurea solstitialis) in the Salmon River Canyon of Idaho

2010 ◽  
Vol 3 (4) ◽  
pp. 462-469 ◽  
Author(s):  
Jennifer L. Birdsall ◽  
George P. Markin
Keyword(s):  
Biological Control ◽  
Control Program ◽  
Centaurea Solstitialis ◽  
Biological Control Agents ◽  
Yellow Starthistle ◽  
Vegetation Monitoring ◽  
Salmon River ◽  
The Past ◽  
Insect Populations

AbstractYellow starthistle is an invasive, annual, spiny forb that, for the past 30 yr has been steadily advancing up the Salmon River Canyon in west central Idaho. In 1994, a decision was made to attempt to manage yellow starthistle by establishing a complex of biological control agents in a containment zone where the weed was most dense. Between 1995 and 1997, six species of seedhead-attacking insects were introduced and successfully established. By 1999, the insects had spread through the entire containment zone. Following this dispersal, a rapid buildup of insect populations occurred, and, since 2003, seed destruction has fluctuated around 90%. Vegetation monitoring plots, however, have shown no consistent decline in the overall population of yellow starthistle, indicating that the amount of seed produced is still sufficient to allow full replacement. However, county weed control personnel, who are responsible for surveying and destroying outlying populations of yellow starthistle beyond the containment zone, report that, during this period, the number of new, isolated pockets of yellow starthistle they are finding has dropped dramatically. This case study discusses how the biological control program partially met the objective of managing yellow starthistle by reducing the rate of advance of this weed in the Salmon River Canyon.

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