BIOLOGICAL CONTROL OF INVASIVE SWALLOW-WORTS IN THE NORTHEASTERN UNITED STATES
Location: Biological Integrated Pest Management Unit
Title: Mapping the current and projected ranges of two swallow-wort invasive vines
Submitted to: Proceedings of Northeastern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: November 30, 2009
Publication Date: January 4, 2010
Citation: Little, N., Morse, S., Ditommaso, A., Milbrath, L.R. 2010. Mapping the current and projected ranges of two swallow-wort ionvasive vines. Proceedings of Northeastern Weed Science Society. p. 54.
Knowing whether a plant species is likely to be locally invasive is important to controlling the spread of such plants and protecting native ecosystems. This is made more difficult by the fact that some introduced plants become invasive in some areas but remain innocuous in other regions. Two species that have become invasive in northeastern North America, especially during the last two decades, are the perennial herbaceous vines: black swallow-wort (Cynanchum louiseae (L.) Kartesz & Gandhi [= Vincetoxicum nigrum (L.) Moench]) and pale swallow-wort (Cynanchum rossicum (Kleopow) Borhidi [= Vincetoxicum rossicum (Kleopow) Barbar.]) [Apocynaceae]. The goal of this study was to use herbaria records, data from individual swallow-wort researchers, and geographic information system (GIS) tools to map and analyze the current known range of these two species and, from this information, project potential distributions in the continental United States. At present, black swallow-wort locations are clustered in the northeastern and upper midwestern states. Records of black swallow-wort in California were of plants growing in the UC Riverside Botanical Garden. Pale swallow-wort locations are currently clustered in the northeastern states, with no records found for the upper midwest states. We found 199 records of black swallow-wort with locations in the following states: California (2), Connecticut (6), Illinois (26), Kansas (3), Massachusetts (22), Maryland (1), Maine (4), Michigan (2), Minnesota (5), Missouri (1), New Hampshire (2), New Jersey (1), New York (65), Pennsylvania (10), Rhode Island (12), Vermont (6), and Wisconsin (22). There were 138 records of pale swallow-wort, with locations in the following states: Connecticut (7), Massachusetts (6), New York (119), and Pennsylvania (1). Nine records of black swallow-wort and five records of pale swallow-wort had no state listed in the record (or information from which the state could be deduced), but were found in the database of the Brooklyn Botanic Garden and so were likely collected in New York State. We generated three potential black swallow-wort distribution maps and two pale swallow-wort distribution maps based on the ranges of climate variables in their current known locations. Although the maps generated are rather coarse given the amount of data collected, they do suggest that projected ranges for these two invasive vines could expand substantially relative to current distributions. For example, the distribution of black swallow-wort is predicted to increase especially in the midwestern U.S., while the distribution of pale swallow-wort is expected to expand most in the Great Lakes region. These findings should help land managers in potentially affected regions to begin planning for early detection and rapid response programs against these two aggressive vines.