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    The Hawkweed Consortium will be meeting at the 2010 Invasive Species in Natural Areas Conference in Idaho.  More details coming soon!

    NEW! Montana Hawkweed Identification Bulletin now available.  To order more copies, contact Montana State University Extension Publications by clicking here.

     

  • resources

    Check out our resources page with many guides, fact sheets, and regional maps to help you identify the hawkweed complex. 

       

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    Established in 1948 as the Europe Station of the Commonwealth Institute of Biocontrol, CABI Europe-Switzerland has traditionally worked on the classical biological control of invasive insect pests and weeds of Eurasian origin, on behalf of the temperate areas of the world, particularly North America, Australia, and New Zealand.

     

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    hawkweed biocontrol consortium

    biocontrol insects

    Dr. Gitta Grosskopf-Lachat is the lead biocontrol researcher at CABI working on the hawkweed insects. CABI researchers and MSU research Dr. Jeff Littlefield have collected and tested eight insect species for three invasive hawkweeds.  The three invasive hawkweeds targeted for biocontrol are:

    • mouse-ear hawkweed (P. officinarum, H. pilosella)
    • orange hawkweed (P. aurantiaca, H. aurantiacum)
    • meadow hawkweed (P. caespitosa, H. caespitosum, H. pratense)

    The biocontrol insects damage the stolons, roots, and stems of the plant impacting seed production and limited spread.  Three of the initial eight insects were found to feed on native species in host-specific testing so now the testing is limited to five remaining insects. 

    Hawkweed plants used for biocontrol open field insect testing.
    Hawkweed plants used for biocontrol open field insect testing.

    gall wasp

    The parthenogentic gall wasp (Aulacidea subterminalis) ovipositions into the stolons of orange and mouse-ear hawkweeds in host range testing.  Currently, the gall wasp screening is being completed at Montana State University (MSU) by Dr. Jeff LIttlefield.  MSU hopes to submit a peitition for release of this insect to the Technical Advisory Group (TAG) in 2009.  MSU and CABI have been mass rearing the insects in quarantine since 2008 in anticipation that this insect will be approved for release.

    Gall wasp (Aulacidea subterminalis) ovipositing on hawkweed.
    The Gall wasp (Aulacidea subterminalis) ovipositing on hawkweed.

    Insect galls on mouse-ear hawkweed.
    Insect galls on mouse-ear hawkweed.

    hover fly

    The two hover flies (Cheilosia urbana, Cheilosa psilophthalma) impact different parts of of the hawkweed plant.  C. urbana impacts the roots while C. psilophthalma eats the above-ground plant parts.  A petition to the Technical Advisory Group (TAG) is currently being compiled by Dr. Gitta Grosskopf-Lachat for Cheilosia urbana in 2009.  Testing for Cheilosa psilophthalma is progressing slowly because it is less common in the field.  Preliminary results reveal invasive hawkweeds in open-tests are not attacked.  However, more testing is need for this insect.


    Hover fly (Cheilosa urbana) impacts hawkweed roots.
    Hover fly (Cheilosa urbana) impacts hawkweed roots.

    Hovery fly eats above-ground plant parts.
    Hover fly  (Cheilosa psilophthalma) eats above-ground plant parts.

    NEW!  stem gall wasps

    Two different populations of stem gall wasps (Aulacidea hieracii and Aulacidea pilosellae) are currently being investigated.  These gall wasps reduce the number of flower heads and inhibit flowering of hawkweed plants.  One population was collected in the Ukraine and the other one in Russia.  The Ukraine population has already shown impacts on the meadow hawkweeds and the first round of tests are being conducted on the Russian insects in 2009. 

    Aulacidea hieracii galls on meadow hawkweed.
    Aulacidea hieracii galls on meadow hawkweed.

    Hover fly (Cheilosa psilophthalma).
    Aulacidea pilosellae ovipositing into a stolon.

    More research is needed on these new stem gall wasps.  However, Hawkweed Biocontrol Consortium funds have decreased and this project will not continue until more money is secured.  To contribute to the Hawkweed Biocontrol Consortium, please contact marijka@uidaho.edu

    new Zealand insects

    There are also many insects released on hawkweeds in New Zealand where they too are invasive.  There are four invasive hawkweed species in New Zealand with the most troublesome being mouse-ear hawkweed (Hieracium pilosella).  Five insects have already been approved for release in New Zealand.  New Zealand does not have any native hawkweeds so the biocontrol approval process has progressed more quickly than in North America.

    gall midge

    The gall midge (Macrolabis pilosellae) has been released for biocontrol on invasive hawkweeds in New Zealand and is now established in the field.  The multivoltine gall midge galls the rosette center, flower heads, and stolen tips of hawkweeds.  Larval feeding on the leaf tissue prevents the unfolding of the leaves.  In no-choice tests the gall midge did develop on most native North American Hieracium spp. so this agent was removed from the list of potential North American agents.

    Female gall midge (Macrolabis pilosellae).
    Female gall midge (Macrolabis pilosellae) ovipositing.

    For more information on hawkweed biocontrol research, contact Gitta Grosskopf-Lachat.