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Proposed Phragmites Host Specificity Test Plant List by Bernd Blossey1, Richard Casagrande2, Patrick Häfliger3, Lisa Tewksbury2 1 Ecology and Management
of Invasive Plants Program, Department of Natural Resources,
Fernow Hall, Cornell University, Ithaca NY 14853, USA
Instructions for Review Process Background Since 1998 we have studied insects in Europe to assess their suitability for control of invasive Phragmits australis in North America. We have finally settled on four different shoot mining noctuid moth species. The next step in the development of biological control is detailed host specificity screening. We have proposed a list of about 48 species (or haplotypes) for host specificity testing (TABLE 1). To select these species we used the USDA Plants Database, and the Flora of North America. We concentrated on east coast species and those that have large enough stem diameters to allow development of the biological control agents, which are all stem feeders (see section on control agent biology below). We would appreciate your feedback on the proposed test plant list before we submit for approval to TAG (Technical Advisory Group for Biological Control of Weeds in North America). We invite comments for addition/deletions to this list. However, any additions to the list will most likely mean a deletion to keep the total number of species to approximately 50. When proposing substitutions, please use scientific names because common names are not consistent and often confusing. To help structure the responses according to categories TAG has already developed (and we followed in this list) please use one or more of the following categories: 1. Species in the same family as Phragmites australis (Poaceae) At present the list contains at least 1 representative species of 6 subfamilies of the family Poaceae (Fig. 1) 2. Species with similar morphology or chemistry 3. Species in the same habitat 4. Species that are hosts of close relatives of the control agents 5. Species of ecological importance (rare, wildlife food) 6. Economically important species 7. Other (please be very convincing if you recommend something else that does not fall into one of the above categories. Just because a species is locally rare is not a good argument for inclusion in a testing sequence). Please also keep in mind that in order to be tested, we need to locate seed or plant sources. Please let us know if you are able to help locate specimens (either those that you propose or those that are already on the list). Please share this document with people you consider interested in Phragmites and the development of biological control. Please address all comments to:
Biology of select potential biological control agents (adopted from Häfliger et al 2006) Archanara geminipuncta is the most commonly encountered noctuid stem borer on P. australis in Europe. Adults (wingspan 28-37 mm) fly in July and August. Soon after emergence, females mate and begin to lay eggs in individual rows under leaf sheaths and eggs overwinter. Hatching first instars start feeding in the soft, and nutrient rich internodes in April soon after shoots begin to grow. As larvae grow, they quickly exhaust food resources of individual shoots and larvae change shoots three to four times during their development. Mature larvae locate an undamaged internode with a minimum diameter of 5 mm for pupation. Attacked stems (but not those where only pupation occurs) show characteristic signs of damage that differ depending on larval development stage. Stems attacked by early instars wilt and die completely; stems attacked by later instars wilt, loose stem tips, and might develop one to four side shoots. Reports on the impact of Arch. geminipuncta on P. australis performance differ but up to 90% of stems can be attacked with shoot heights and above ground biomass reduced by 50-60% and 20-60%, respectively Archanara dissoluta is the second most commonly mentioned Archanara species in Europe. Adult Arch. dissoluta (wingspan 27-33 mm) fly in July and August and lay eggs in two to three rows under leaf sheaths where they overwinter. Larvae hatch in spring and need to change shoots to complete development. Archanara neurica is the least common of the three known Archanara species feeding on P. australis in Europe. Adults (wingspan 26-29 mm) fly in July and females lay eggs under leaf sheaths where they overwinter. Larvae hatch in spring and need to change shoots to complete development and seem to select thinner stems growing in drier situations compared to the other Archanara species. Arenostola phragmitidis seems to have a more northern and eastern distribution in Europe compared to the Archanara species. Although Aren. phragmitidis is locally common in England and widespread in marshes in the Netherlands and in Denmark, little is known about abundance, impact, larval development and mortality factors. The creamy ochreous adults (wingspan 32-36 mm) fly in July and August and lay eggs under leaf sheaths where they overwinter. As with the Archanara species, larvae hatching in spring need to change shoots to complete development. In contrast to the Archanara larvae, pupation occurs not in the shoots but in damp moss and litter on the ground. Pupation requirements appear to restrict Aren. phragmitidis to land reed. Taxonomy of the grass family (Poaceae, Gramineae) For a recent treatment of the taxonomy of the grasses please visit: http://www.virtualherbarium.org/teach/GrassSys/ Alternatively, you may want to consult the Flora of North America. List of Plant Species Recommended for Testing to Determine Potential Host Range of Candidate Biological Control Agents of Phragmites australis(CAV.) Trin. Ex Steud (Common Reed) Class Liliopsida, Order Cyperales, Family Poaceae, Subfamily Arundinoideae.
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