Submitted to: Journal of British Columbia Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 28, 2003
Publication Date: December 1, 2003
Citation: Horton, D.R., Lewis, T.M. 2003. Numbers and types of arthropods overwintering on common mullein, Verbascum thapus L (Scrophulariaceae), in a central Washington fruit-growing region. Journal of Entomological Society of British Columbia. 100:79-87. Interpretive Summary: Numbers of insects and mites overwintering on a common weed adjacent to pear and apple orchards was determined. Over 45,000 insects and mites were collected from plants in the winter of 2000-2001. The samples included insects in 8 Orders and 30 Families, and were distributed in both the basal leaf rosettes and in the old flowers and seed capsules of the stalks. Populations were dominated numerically by mites and thrips. Several pest and beneficial arthropods were common in the samples. Pests included western flower thrips, Lygus bugs, and spider mites. Predators included western predatory mite and minute pirate bug. Sites that were near one another geographically were not necessarily similar in terms of the types and numbers of overwintering pests and predators.
Technical Abstract: Densities and types of arthropods overwintering on common mullein, Verbascum thapsus L., in a fruit-growing region of Central Washington were determined. Over 45,000 arthropods were collected from 55 plants (5 plants from each of 11 sites), dominated numerically by Acari and Thysanoptera. Insects representing 8 Orders and 30 Families were identified, distributed both in the basal leaf rosettes and in the stalk material of the plants. One specialist insect herbivore of mullein, the mullein thrips, Haplothrips verbasci (Meyer), was abundant at all sites. Several pest and predatory taxa that commonly occur in orchards were also collected, suggesting that mullein may be a source of overwintered pests or predators moving into orchards in early spring. Pest taxa included primarily western flower thrips (Frankliniella occidentalis (Pergande)), Lygus spp., and tetranychid spider mites. Common predators included phytoseiid mites and minute pirate bugs (Orius tristicolor (White)). Sites that were geographically close to one another were not more similar (in taxonomic composition of overwintering arthropods) than more distantly separated sites.