You are here: Home
/ Publication Information
Title: Resource use and clonal differences in attack rate by the Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), in France
Author: Rappaport, Nancy; Roques, Alain;
Source: Canadian Entomologist, Vol. 123: 1219-1228
Publication Series: Miscellaneous Publication
Description: The within-cone distribution of Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), the Douglas-fir seed chalcid, infesting Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] cones from north-central France was compared with that in samples from California. Results indicate that the mid-region of cones was more intensively utilized by seed chalcids in France than in California, whereas in the northwestern United States the mid-region is characteristically occupied by dipteran and lepidopteran species. This difference in distribution may explain the large discrepancy in infestation rates on the two continents. The potential impact of this finding on pest management strategies is discussed.
Cones were measured and dissected or X-rayed to determine seed chalcid infestation levels. Analysis of covariance performed on data from cones that were collected in 1986 and dissected showed cone diameter at maturity to be a highly significant factor in attack rate, although slopes were different among clones. Between-tree variation was also significant, but clonal source was not. Cone diameter, clonal source, and between-tree variation constituted 87.1% of the variation in rate of attack by the seed chalcid. Although clone was not a significant factor in data from dissected cones, X-rayed cones showed significant differences in attack rates for some clones.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
XML: View XML
Rappaport, Nancy; Roques, Alain 1991. Resource use and clonal differences in attack rate by the Douglas-fir seed chalcid, Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), in France. Canadian Entomologist, Vol. 123: 1219-1228
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility