Phytophagous arthropods of invasive swallow-wort vines (Vincetoxicum spp.) in New York.

Pale swallow-wort (Vincetoxicum rossicum [Kleopow] Barbar.) and black swallow-wort (V. nigrum [L.] Moench), European species of herbaceous, perennial viny milkweeds, have become increasingly invasive in various natural and managed habitats in the northeastern United States and southeastern Canada, including low- and high-light habitats. A classical biological control program is being developed, but almost no information was available on the current arthropod fauna for either species in the invaded range. I conducted quantitative surveys on pale and black swallow-wort at several locations in New York State over 3 yr to identify and compare the seasonal assemblage of phytophagous arthropods that are feeding and developing on the plants in sunny and shaded habitats. Of the approximately 84 nonpredatory species collected, 10 polyphagous, ectophagous species of native and exotic arthropods were identified, exclusively from the leaves or stems, which could develop to the adult stage and in most cases complete at least one generation on one or both species of swallow-wort. However, their densities were low throughout the season and generally did not differ between the sunny and shaded habitats. Very little to no damage was observed on the plants. Exotic swallow-worts seem to have been released from specialized natural enemies and have not accrued a damaging suite of generalist herbivores. This may be a contributing factor in the increasing invasiveness of these weeds, and biological control appears promising for these plants.