Bittersweet nightshade, Solanum dulcamara L. (Solanales: Solanaceae), was sampled at numerous locations in Washington and Idaho. Adults of 8 species of thrips (Thysanoptera) from 3 families were collected, including the worldwide plant pests Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thripidae), which are vectors of the serious plant viruses in the genus Tospovirus. Aeolothrips fasciatus Hinds (Aeolothripidae), a predator of small insects, also was collected.
Bittersweet nightshade, Solanum dulcamara L. (Solanales: Solanaceae), is a native plant in parts of Europe and Asia. It was introduced and is established in the eastern, north-central, and Pacific Northwest regions of the USA. It is commonly found in grasslands and meadows and occurs most frequently in riparian areas, wetlands, and deciduous forests (Waggy 2009). We report here various thrips (Thysanoptera) species collected from samples of S. dulcamara in Washington and Idaho.
Patches of S. dulcamara were found along irrigation canals and ponds near cultivated areas. Samples were taken with a D-Vac sucking device (Model 24, Rincon-Vitova Insectaries, Inc., Ventura, California) from the entire above-ground portions of the plants from Jun to Nov in 2012 and in Aug and Oct in 2013 (Table 1). Solanum dulcamara grows using other plants as support. Seventeen species of surrounding plants were identified, including Elaeagnus angustifolia L. (Rosales: Elaeagnaceae), Typha sp. (Poales: Typhaceae), Asclepias syriaca L. (Gentianales: Apocynaceae), and Salix sp. (Malpighiales: Salicaceae). The D-Vac tube was placed over the plant patch for approximately 10 s. Subsamples were taken depending on the size of the patch. Insects collected in the mesh bag were placed on dry ice for transport to the laboratory. Only adults were sorted and identified to species. However, thrips larvae of unidentified species were observed on the plants from Colfax in Jun 2013, Moses Lake in Jul and Aug, Mesa (new) in Jun, and Mattawa in Jun and Sep. Thrips were extracted under stereomicroscopy in 90% ethyl alcohol. Adults were mounted in Canada balsam for identification using the procedures in Wirth & Marston (1968) and the keys in Hoddle et al. (2012). Vouchers of each species were deposited at the North Florida Research and Education Center, University of Florida, Quincy, Florida.
Adults of 8 species of thrips from 3 families were collected (Table 2). Species of Thripidae included the phytophagous Caliothrips fasciatus (Pergande), Chirothrips aculeatus Bagnall, Frankliniella occidentalis (Pergande), Thrips hawaiiensis (Morgan), and Thrips tabaci Lindeman. Both F. occidentalis and T. tabaci are worldwide pests of many crops, and they are vectors of the plant viruses in the genus Tospovirus (Bunyaviridae) (Hoddle et al. 2012). Solanum dulcamara is a confirmed host for Tomato spotted wilt virus (Parrella et al. 2003), and F. occidentalis is a confirmed vector of this tospovirus species to S. dulcamara (Stobbs et al. 1992).
Adults of 2 species of Phlaeothripidae were collected (Table 2). Haplothrips verbasci (Osborn) reproduces on the stems and flowers of Verbascum thapsus L. (Lamiales: Scrophulariaceae) (Comegys & Schmitt 1965; Hoddle et al. 2012; Wilbur et al. 2013). This plant species was identified growing near S. dulcamara in eastern Washington. Cephalothrips monilicornis (Reuter) reproduces on the leaves of various Poaceae (Hoddle et al. 2012). Four species of Poaceae were identified growing close to S. dulcamara. Aeolothrips bicolor Hinds in the family Aeolothripidae was collected. Insects in the order Thysanoptera are mainly phytophagous or mycophagous, and obligate predation is limited to only several lineages (Mound 2005). Species of Aeolothrips are predatory on small insects including other species of thrips.
Sample locations, coordinates, sampling dates, and plant stage.
Species of thrips and total numbers of adults found sampling Solanum dulcamara patches in Idaho and Washington.
A host plant is one on which an insect can reproduce (Mound 2013), and more research is needed to determine which species of thrips utilize S. dulcamara as a host plant. Our results suggest that the plant is potentially a source of economically important thrips invading crop fields.
We thank the Northwest Potato Research Consortium for supporting this research, and Marcus Hooker for identifying the plants (Marion Ownbey Herbarium, School of Biological Science, Washington State University).