Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2009
Publication Date: 2/5/2010
Citation: Milbrath, L.R. 2010. Phytophagous arthropods of invasive swallow-wort vines (Vincetoxicum spp.) in New York. Environmental Entomology. 39:68-78. Interpretive Summary: Pale and black swallow-wort are exotic vines that have become increasingly invasive in various habitats in the northeastern United States and southeastern Canada, including low- and high-light habitats. It is of interest to know what insects and mites currently attack these plants here in North America, and what damage they cause to the plants, prior to introducing approved natural enemies from Europe for the biological control of swallow-wort. I therefore surveyed field populations of pale and black swallow-wort growing in old fields and forest understories in New York State over three years. Ten species of insects and mites, all of which feed on a broad range of plant species, were identified from the leaves or stems that could successfully develop to the adult stage and in most cases reproduce on one or both species of swallow-wort. However, they rarely reached high densities and appear to have no impact on the plants in either type of habitat. All other parts of the plants remained free of insects and mites. Exotic swallow-worts therefore appear to have been released from natural enemies, which may be a contributing factor in the increasing invasiveness of these two weeds.
Technical Abstract: 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 84 nonpredatory species collected, 10 polyphagous, ectophagous species of native and exotic arthropods were identiÞed, 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.