02420naa a2200385 a 450000100080000000500110000800800410001910000190006024501830007926000090026252013110027165000230158265000130160565000120161865000170163065000170164765000100166465000230167465000130169765000100171065000250172065000250174565000100177065300280178065300120180865300100182065300170183065300240184765300210187165300260189265300150191865300160193370000180194977300670196712786552025-07-29       1989    bl uuuu     u00u1 u    #d1 aSWEENEY, J. D.  aDistribution of Barbara colfaxiana (Kearfott) (LepidopterabTortricidae) eggs within and among Douglas-fir crowns and methods for estimating egg densities.h[electronic resource]  c1989  aThe spatial and frequency distributions of eggs of Barbara colfaxiana in Douglas-fir trees and stands (Pseudotsuga menziesii) were determined by dissecting 13 262 conelets collected from 81 trees at 3 sites over 2 years in British Columbia. There were no consistent trends in egg density associated with crown level or aspect. The frequency distribution of eggs per conelet fitted the negative binomial in 3 of 5 site-years but a common k for the negative binomial could not be calculated. R.H. Green's index of aggregation suggested that the egg distribution was significantly aggregated in each site-year. The optimal number of conelets per tree to sample was determined to be 4 in forest stands and 3 in seed orchards. The number of sample trees required for estimating mean egg density with 10% and 20% precision and 90% confidence was calculated for a range of mean egg densities using the method of E. Kuno. The sample sizes required to estimate a control threshold density of 0.6 eggs/conelet with 10% precision and 90% confidence were very large and would be impractical for operational use. Therefore, a sequential sampling plan was developed for use in seed orchards that would classify cone moth egg densities as either above or below a critical density at which 10% seed loss would be expected.  aBarbara colfaxiana  aconifers  aecology  aforest pests  ainsect pests  apests  apopulation density  asampling  aseeds  aspatial distribution  astatistical analysis  atrees  aAgricultural entomology  aBiology  aCones  aDistribution  aEconomic thresholds  aMariposa de cone  aPseudotsuga menziessi  aTechniques  aTontricidae1 aMILLER, G. E.  tCanadian Entomologist, Ottawagv. 121, n .7, p. 569-578, 1989.