Target Invasive Plants and Biocontrol Agents Undergoing Screening

The BC Ministry of Forests and Range (MFR), through contributed funding, enable research into potential new biocontrol agents for the province on an annual basis. Research on potential biocontrol agents is funded by a consortium of interested partners including Canadian provincial and federal government departments, US county, state and federal agencies, US and Canadian Universities and NGO's. Specific funding and research partners vary with each plant targeted. For prioritization of invasive plants requiring biological control see Priorities for New Biocontrol Agents . For an explanation of the process to attain biological control agents, see Screening Process .

The invasive plants that are targeted by biocontrol consortia in which British Columbia participates and their consortia objectives in 2008/09 are:

Common tansy (Tanacetum vulgare)

The consortium has developed a test plant list for common tansy. The chemical variability of common tansy populations is also being investigated with respect to host plant acceptance by biocontrol agent candidates.  A literature review and field surveys have resulted in focus on four potential agents: the stem-boring moth Isophrictis striatella; the stem-boring weevil Microplontus millefollii; the root-feeding beetle Longitarsus noricus; and, the leaf-feeding beetle Cassida stigmata.

Specific objectives:

  • Conduct field surveys in Europe for potential new biocontrol agents;
  • Rearing and host range tests with C. stigmata, M. millefollii and L. noricus; and
  • Investigations on larval development of I. striatella to enable host range test to be conducted.

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yellow toadflax

Dalmatian and yellow toadflax (Linaria dalmatica and vulgaris)

Host range studies for toadflax, focussing on yellow toadflax, are well underway and continuing.

Specific objectives: 

  • Conduct studies on interactions between gall forming weevils and genetic variation in toadflax;
  • Continue host range studies with Rhinusa pilosa , stem-galling weevil, focussing on yellow toadflax, and compile information obtained to date; and
  • Continue host preference and start host range studies with M. heydeni (ex L. vulgaris) again, focussing on yellow toadflax.
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Hawkweed complex (Hieracium spp.)

Studies for potential biocontrol agents of several hawkweed species are on-going.  Host-specificity screening has been completed by Dr. Jeff Littlefield of Montana State University for the stolon-tip gall wasp Aulacidea subterminalis targeting Pilosella officinarum and P. aurantiaca.  Petitions for release have been submitted in the US and Canada in December 2008 and February 2009, respectively. Both countries are awaiting the outcomes.  An additional biocontrol agent candidate has been added to the studies in 2008, the gall wasp A. hieracii ex Pilosella collected from the Ukraine.  No other potential biocontrol agents were found during surveys to eastern Germany, eastern Austria, Poland, Slovakia, the Czech-Republic and southern Russia.

Specific objectives:

  • Complete host-specificity screening of the hawkweed root-feeding hover fly, Cheilosia urbana , and
  • Host-specificity screening of the hawkweed crown-feeding hover fly, Cheilosia psilophthalma (Diptera: Syrphidae) and the gall wasp Aulacidea hieracii ex Pilosella.
yellow hawkweed orange hawkweed
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Knotweed (Fallopia/Polygonum)

Work on this plant is in the initial stages of screening of North American test-plants. BC contains four separate species: Japanese (Fallopia japonica or Polygonum cuspidatum); Bohemian (F. bohemica, hybrid); Giant (F. sachaliensis or P. sachalinense); and, to a lesser extent, Himalayan (P. polystachyum) knotweed. Knotweed’s ability to hybridize has caused some difficulties in differentiation between the species but also requires consideration for biocontrol agent host range acceptance.  Additionally, cold tolerance and development studies with the candidate agent Aphalara itadori (sap sucker psyllid) has shown that this insect will establish well in both the US and Canada within the current knotweed distributions.

Specific objectives:

  • Host-range screening of candidate agents, including but not limited to Aphalara itadori and the fungal leafspot Mycospharella sp. for their ability to feed, reproduce and develop on non-target North American species with a focus on testing of A. itadori strains against mature plants of key species that have been impossible to propagate from seed collected in previous years and genetically-characterized knotweed lines; and,
  • Propagate and multiply existing plant populations of BC knotweed strains for US collaborators to conduct molecular analysis.
knotweed
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Oxeye daisy (Leucanthemum vulgare)

In 2008, a literature study was conducted to investigate European insect species that feed on oxeye daisy.  Of the resulting 80 insect species, approximately 25% are believed to have a narrow host range.  Twenty-six sites were surveyed in the Swiss Jura, the Swiss Alps, the French/German Rhine Valley and the Pyrenees to find biocontrol agent candidates.  A test plant list has been drafted in 2008.

Specific objectives:

  • Continue review of herbarium specimens, survey the plants, and develop potential host plant test-list for screening of biocontrol agents;
  • Conduct further surveys for potential agents; and
  • Begin establishing rearing colonies for the most promising insects and, if possible, conduct preliminary host-specificity tests.
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Sulphur cinquefoil (Potentilla recta)

The investigation into potential biocontrol agents for sulphur cinquefoil began in 1992 but ended prematurely in 2002 due to funding issues for the consortium and difficulties encountered in determining a host-specific biocontrol candidate.  In 2008, BC funded a risk analysis of sulphur cinquefoil including: review the work on biological control to date; assess and quantify risks of available biocontrol agents with available data; and, identify data gaps.  Also in 2008, preliminary choice and no-choice tests were conducted with the Diastrophus spp. (gall wasp) that had been collected during the surveys of another plant species.  A gall midge (not yet identified) was also exposed to potted plants to rear the insect.  No resulting galls or agents came from these tests.

Specific objectives:

  • Conduct additional surveys in the Black Sea area, e.g. Southern Russia, eastern Turkey and the Ukraine, pending the Province’s review of the risk analysis.
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Tansy ragwort (Senecio jacobaea)

The host-range testing of a cold hardy Swiss strain of Longitarsus jacobaeae, a root-feeding beetle has been completed.  A different strain of this agent is already well-established on the lower mainland in BC but has yet to survive a transfer to the more variable seasons experienced in the interior.

Specific objectives:

  • Completion of petition to request importation of the cold hardy Swiss strain of Longitarsus jacobaeae; and,
  • If the petition is approved, import and distribute the beetle.
Tansy ragwort infestation Tansy ragwort
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