Impact of herbivory on performance of Vincetoxicum spp., invasive weeds in North America
- 226 Downloads
The alien invasive vines Vincetoxicum rossicum and Vincetoxicum nigrum (swallow-wort) are of major concern in eastern North America, where both species invade forested landscapes and threaten faunal and plant diversity. Among the few native natural enemies reported in Eurasia, the specialist chrysomelid, Chrysochus (Eumolpus) asclepiadeus (Coleoptera; Chrysomelidae), feeds on Vincetoxicum both above ground (as adults) and below ground (as larvae). The goal of our study was to assess the potential for using this beetle to manage invasive Vincetoxicum spp. in North America by quantifying the impact of herbivory by C. asclepiadeus on Vincetoxicum and determining whether this effect was influenced by plant density (“Allee effect”). Experimental work was carried out using a split plot design in the field in southern France. Pots of V. nigrum and V. hirundinaria, a substitute for V. rossicum, were planted at high (255 plants/m2), medium (127 plants/m2), and low (32 plants/m2) plant densities, and received treatments of 0 (control), 2 or 4 C. asclepiadeus adult beetles/pot. Leaf damage, root and shoot biomass, and quantity of seeds were measured after 4 weeks of adult feeding. Densities of 2 and 4 beetles/pot caused similar damage, with significant reductions in plant biomass at low plant density. While V. hirundinaria increased allocation of resources to roots in response to herbivory, V. nigrum did not. Seed production was greatest for both species grown at low plant densities, but only V. nigrum produced fewer seeds in response to herbivory. Our results, based on the effects of herbivory by C. asclepiadeus adults, suggest that if this beetle were to be introduced into North America for the management of Vincetoxicum spp. such as V. rossicum, reductions in plant biomass and spread would be greatest if beetles were released on edges or in newly-established satellite populations at low plant densities. In the case of V. nigrum, beetles could be released irrespective of plant density as reproductive output and seed dispersal would be reduced similarly.
KeywordsInvasive species Herbivory Plant fitness Biological control Apocynaceae
This work was funded by the Ontario Ministry of Natural Resources (OMNR), the USDA-ARS and supported by R. Bourchier (Agriculture and Agri-Food Canada). The authors thank Olivier Simonot and Yves Garnier (USDA-ARS European Biological Control Laboratory) for field and technical assistance. We also thank three anonymous reviewers for their comments that improved the quality of this paper.
- DiTommaso A, Lawlor FM, Darbyshire SJ (2005) The biology of invasive alien plants in Canada. 2. Cynanchum rosicum (Kleopow) Borhidi [=Vincetoxicum rossicum (Kleopow) Barbar.] and Cynanchum louiseae (L.) Kartesz & Gandhi [=Vincetoxicum nigrum (L.) Moench]. Can J Plant Sci 85(1):243–263Google Scholar
- Milbrath LR, Biazzo J, Sforza R, Berner D, Casagrande R (2006) Proposed host specificity test plant list for testing potential biological control agents of swallow-worts in North America. USDA Agricultural Research Service Research Proposal, pp 1–31Google Scholar
- Miller GC, Kricsfalusy V, Moleirinho P, Hayes S, Krick R (2008) Dog-strangling vine- Cynanchum rossicum (Kleopow) Borhidi: A review of distribution. ecology and control of this invasive exotic plant. Toronto Region Conservation Authority, Rouge Park DSV Report, pp 1–62Google Scholar
- Mullin BH, Anderson LWJ, DiTomaso JM, Eplee RE, Getsinger KD (2000) Invasive plant species. Council for Agricultural Science and Technology. Issue Paper 13:1–18Google Scholar
- Notzold R, Blossey B, Newton E (1998) The influence of belowground herbivory and plant competition on growth and biomass allocation of purple loosestrife. Oecologia 113:82–93Google Scholar
- R Development Core Team (2005) R: a language and environment for statistical computing, reference index version 2.9.1. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org
- Royall RM (1997) Statistical evidence: a likelihood paradigm. Chapman and Hall, New YorkGoogle Scholar
- Sforza R (2009) Survey in Eurasia for collection of germplasm, natural enemies, and selection of agents for the biological control of swallow-worts (Vincetoxicum spp.) in North America. Phase I, USDA-ARS Research Final Report. Montpellier, France, pp 40Google Scholar
- Tewksbury L, Casagrande R, Gassmann A (2002) Swallow-worts. In: Van Driesche R et al (eds) Biological control of pests in forests of Eastern United States, USDA Forest Service Publication FHTET-2002–04, pp 209–216Google Scholar
- Weston LA, Barnet JN, DiTommaso A (2006) Review of the biology and ecology of three invasive perennials in New York State: Japanese knotweed (Polygonum cuspidatum), Mugwort (Arternisia vulgaris) and pale swallow-wort (Vincetoxicum rossicum). Invasive Plant Council of New York State. http://www.ipcnys.org. Retrieved 12 Oct 2009
- White DJ, Haber E, Keddy C (1993) Invasive plants of natural habitats in Canada: an integrated review of wetland and upland species and legislation governing their control. Canadian Wildlife Service, Ottawa, p 121Google Scholar