Hostname: page-component-848d4c4894-2xdlg Total loading time: 0 Render date: 2024-07-06T03:43:19.340Z Has data issue: false hasContentIssue false
  • English
  • Français

DISPERSAL OF CONE AND SEED INSECTS TO AN ISOLATED DOUGLAS-FIR TREE IN WESTERN OREGON

Published online by Cambridge University Press:  31 May 2012

T. D. Schowalter
T. D. Schowalter
Affiliation:
Depattrnent of Entomology, Oregon State University, Cowallis, Oregon 97331
Get access Rights & Permissions [Opens in a new window]

Extract

Cone and seed insects frequently cause severe losses to Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed production in the Pacific Northwest (Hedlin et al. 1981; Ruth 1980). Two of the major species west of the Cascades are the Douglas-fir cone gall midge (Contarinia oregonensis Foote (Diptera: Cecidomyiidae)) and the Douglas-fir seed chalcid (Megastigmus spermotrophus Wachtl. (Hymenoptera: Torymidae)). These two species are host specific on Douglas fir and exhibit an extended diapause in which more than 50% of each year's cohort may remain in diapause under host trees for 1 or more years (Annila 1982; Hedlin 1961; Hedlin et al. 1981; Johnson 1962). The economic and biological costs of chemical control have supported recommendation of alternative control measures, particularly (1) establishing seed orchards some distance from sources of coneand seed-insect populations, and (2) removing all cones and burning litter as a means of reducing such populations (Hedlin et al. 1981; Ruth 1980). The success of these two options depends on the dispersal strategies of cone and seed insects (Johnson 1962), but information on dispersal has been lacking. The purpose of this study was to obtain such information.

Type
Articles
Information
The Canadian Entomologist , Volume 116 , Issue 10 , October 1984 , pp. 1437 - 1438
Copyright
Copyright © Entomological Society of Canada 1984

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Annila, E. 1982. Diapause and population fluctuations in Megastigmus specularis Walley and Megastigmus spermotrophus Wachtl. (Hymenoptera, Torymidae). Ann. Ent. Fenn. 48: 33–36.Google Scholar
Hedlin, A. F. 1961. The life history and habits of a midge, Contarinia oregonensis Foote (Diptera: Cecido-myiidae), in Douglas-fir cones. Can. Ent. 93: 952–967.CrossRefGoogle Scholar
Hedlin, A. F., Yates, H. O. III, Tovar, D. C., Ebel, B. H., Koerber, T. W., and Merkel, E. P.. 1981. Cone and Seed Insects of North American Conifers. Environment Canada, Canadian Forestry Service, Ottawa, ON. 122 pp.Google Scholar
Johnson, N. E. 1962. Distribution of Douglas-fir cone midges in the forest litter beneath young, open-grown Douglas-fir. Can. Ent. 94: 915–921.CrossRefGoogle Scholar
Ruth, D. S. 1980. A Guide to Insect Pests in Douglas-fir Seed Orchards. Environment Canada, Canadian Forestry Service, Pacific Forest Research Center, Victoria, BC. 19 pp.Google Scholar
Wheat, J. and Bordelon, M.. 1980. Seed Orchards of Western Oregon, Western Washington, Northern California and British Columbia. Industrial Forestry Association, Olympia, WA. 48 pp.Google Scholar