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United States Department of Agriculture

Agricultural Research Service

Research Project: Biological Control of Invasive Terrestrial and Riparian Weeds in the Far Western U.S. Region, with Emphasis on Thistles, Brooms and Cape-Ivy

Location: Exotic and Invasive Weeds Research

2013 Annual Report


1a.Objectives (from AD-416):
1) Characterize the diversity and basic biology of target weeds, including yellow starthistle and other weeds such as Russian thistle and Cape-ivy, estimate their potential range and environmental/economic impacts, and determine their regions of origin..
2)Discover and evaluate the host-specificity and potential efficacy of arthropod biological control agents for target weeds such as Cape-ivy, yellow starthistle, Russian thistle, French broom, and Scotch and bull thistles..
3)Evaluate the population dynamics and efficacy of biological control agents, their impact on non-target species, and relevant interactions in associated biological communities and farming systems, for weeds such as Cape-ivy, French broom, yellow starthistle, and Russian, Scotch and bull thistles.


1b.Approach (from AD-416):
We will develop classical biological control programs to help control invasive alien plants such as Cape-ivy, yellow starthistle, Russian thistle, French broom, and Scotch thistle. Molecular genetic methods will be used to help characterize genetic diversity of the target weeds and determine their geographic origin, which are necessary to direct foreign exploration for prospective agents. Climatological analysis of the known geographic distribution of target weeds will predict potential geographic range for invasion in the USA. Field and laboratory experiments will be used to measure the environmental and economic impacts of these target weeds. With the assistance of foreign cooperators, we will discover prospective arthropod biological control agents for the above weed targets. We will evaluate the host-specificity and potential efficacy of these agents in experiments conducted in our quarantine laboratory and in the field where these agents are native. Host specificity bioassays and GC-MS analysis of volatile organic chemicals of target and nontarget plants will help determine the importance of plant secondary chemistry in determining specificity of prospective biological control agents. We will conduct field experiments to study the population dynamics and efficacy of biological control agents after they have been released for weeds such as Cape-ivy, French broom, yellow starthistle, and Russian, Scotch and bull thistles. This will include studies on impact on non-target species, and on possible interactions within targeted biological communities and farming systems. Replacing 5325-22000-020-00D 11/01/2010.


3.Progress Report:
In support of Objectives 1 and 2 of the parent project, specimens of French broom and Scotch broom were collected in California to evaluate genetic similarity to those plants in Australia and New Zealand, where biological control appears to be more effective than in California. The geographic distribution and seasonal phenology of Cape-ivy was studied in coastal California, and five sites on state-owned land were identified as suitable locations for future releases of biological control agents. Positive recommendations for obtaining a field release permit were received for the Cape-ivy fly (Parafreutreta regalis) and Cape-ivy moth (Digitivalva delaireae) from the USDA-APHIS Technical Advisory Group, which is based on host plant specificity data submitted by our Research Unit. Additional greenhouse host range tests confirmed that these two insects do not damage nontarget plants that are present in the U.S. The potential impact of a prospective biological control agent, Arytinnis hakani, a psyllid from France, was measured on French broom in quarantine laboratory tests. A field experiment was conducted with cooperators in Italy to evaluate the host plant specificity of a prospective agent of yellow starthistle, the seed-feeding weevil, Larinus filiformis. A field experiment was conducted with cooperators in Bulgaria to test Larinus latus, a prospective biological control agent of Scotch thistle. Exploration for prospective agents of Scotch thistle and Salsola tragus (common tumbleweed) were continued by cooperators in Turkey, Italy and Bulgaria. A host-specific insect, Ceratapion basicorne, was tested for its ability to detect host plant odors, to better understand how it selects its host plant. We continued to monitor populations of yellow starthistle and biological control agents at long-term study sites in California to evaluate their impact. Long-term field evaluation of the impact and spread of the introduced biological control agent of Dalmatian toadflax, Mecinus janthiniformis, was initiated in response to termination of the California Department of Food and Agriculture Biological Control Program, which previously conducted this work.


Review Publications
Cristofaro, M., Debiase, A., Smith, L. 2012. Field release of a prospective biological control agent of weeds, Ceratapion basicorne, to evaluate potential risk to a nontarget crop. Biological Control. 64:305-314.

Herr, J.C., Carruthers, R.I., Bean, D.W., Deloach Jr, C.J. 2009. Host preference between Saltcedar (Tamarix spp.) and native non-target Frankenia spp. within the Diorhabda elongata species complex (Coleoptera: chrysomelidae). Biological Control. 51:337-345.

Gultekin, L., Cristofaro, M., Borovec, R., Smith, L. 2008. Broad-nosed weevils feeding on Centaurea solstitialis L. in Turkey, with a description of the new species Araxia cristofario sp. n. (Coleoptera: Curculionidae: Entiminae). Annals of the Entomological Society of America. 101(1):7-12.

Fisher, A.J., Ditomaso, J.M., Gordon, T.R. 2005. Intraspecific groups of Claviceps purpurea associated with grass species in Willapa Bay, Washington, and the prospects for biological control of invasive Spartina alterniflora. Biological Control. 34:170-179.

Smith, L., Drew, A.E. 2006. Fecundity, development and behavior of Ceratapion basicorne (Coleoptera: Apionidae), a prospective biological control agent of yellow starthistle. Environmental Entomology. 35(5):1366-1371.

Last Modified: 10/25/2014
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