SEX RATIOS OF THE WESTERN SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

1983 ◽  
Vol 115 (9) ◽  
pp. 1059-1063 ◽  
Author(s):  
Robert W. Campbell ◽  
Torolf R. Torgersen ◽  
Kevin P. Hosman ◽  
Nilima Srivastava
Keyword(s):  
Sex Ratios ◽  
Survival Rates ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Negligible Effect ◽  
Western Montana ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Male And Female ◽  
The One

AbstractPopulations of the western spruce budworm, Choristoneura occidentalis, were sampled in western Montana, central Idaho, and eastern Oregon. In 22 of 24 populations, the proportion of females among pupae did not differ from 0.5. Similarly, in 21 of 24 populations, the proportion of females among adults was not different from 0.5. In all populations, differences between survival rates of male and female pupae were attributed to chance. The proportion of females among pupae (a) did not differ between insects on Douglas-fir and those on grand fir, (b) was slightly but significantly higher among insects in the mid-crown than among those in the lower crown, and (c) was significantly higher among the insects in the one site studied where average defoliation of current-year shoots was greater than 50%. Variation in the proportion of females among adults should have a negligible effect on the dynamics of these populations.

RELATIONSHIPS BETWEEN ATTACK RATES AND SURVIVAL OF WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALIS FREEMAN (LEPIDOPTERA: TORTRICIDAE), AND BUD DEVELOPMENT OF DOUGLAS-FIR, PSEUDOTSUGA MENZIESII (MIRB.) FRANCO

1992 ◽  
Vol 124 (2) ◽  
pp. 347-358 ◽  
Author(s):  
Roy F. Shepherd
Keyword(s):  
Close Association ◽  
Spruce Budworm ◽  
Larval Survival ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Bud Development ◽  
Feeding Sites ◽  
Vegetative Buds ◽  
Wide Range

AbstractIndividual larvae of western spruce budworm (Choristoneura occidentalis Freeman) were observed from overwintering emergence to pupation at six locations spread over a wide range of altitudes and thus climate. A weekly census of 100 lower-crown buds per plot indicated large differences in rates of bud development and larval survival among locations.Emerging second-instar larvae attempted to mine swelling buds of Douglas-fir. If the buds were hard and tight, larvae mined 1-year-old needles until penetrable buds were available. Larvae dispersed over the crowns with only one larva becoming established in each bud; thus, many early-emerging and surplus larvae could not find suitable feeding sites and disappeared. Within the protective bud, survival was high. After buds flushed and larvae became exposed, densities dropped, probably due to increased predation and decreased food quality. Correlations indicated a close association between larval survival for the exposed period between bud flush and pupation, and overall larval survival.Douglas-fir trees responded to initial bud removal, but not to needle removal, by inducing latent buds in the axils of needles to grow into active vegetative buds ready to develop and flush the next spring. The number of these new vegetative buds formed was greatest when the initial buds were removed early in the season before flush, and decreased thereafter. Trees with vigorous crowns had the greatest response to defoliation by inducing the largest number of latent buds into becoming active vegetative buds; these were found mainly on the 2- and 3-year-old internodes.

EARLY GROUND APPLICATION OF ACEPHATE FOR CONTROL OF THE WESTERN SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) ON DOUGLAS-FIR

1977 ◽  
Vol 109 (9) ◽  
pp. 1153-1158 ◽  
Author(s):  
J. Wayne Brewer ◽  
J. O’Neal
Keyword(s):  
Aqueous Solution ◽  
Larval Mortality ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Regression Analyses ◽  
Western Spruce Budworm ◽  
Systemic Action ◽  
Equipment Application

AbstractThe insecticide acephate (0.5-dimethyl acetyl phosphoramidothioate) was applied at 0.5, 1.0, and 1.5 lb A.I./gal (.058, 0.118, 0.179 kg/l.) in aqueous solution to individual Douglas-fir trees infested with western spruce budworm, Choristoneura occidentalis Freeman, larvae in central Washington using hand held ground application equipment. Application was made when larvae were in the needle mining – bud mining stage at rates ranging from 2.58 to 5.10 gal/acre (3.97 to 7.84 l./ha). For all three concentrations, mortality of larvae inside needles was 94–98% after 1 day compared with a check mortality of 18% and larval mortality inside buds was 99% after 1 day compared with 23% for the check. Regression analyses indicated that defoliation was positively correlated with the number of needles mined the current year and per cent punctured buds, and negatively correlated with larval mortality inside both needles and buds. The data suggest that when applied at the rates used, acephate has some type of systemic action and can provide foliage protection during the year of application.

IMPLANTATION AND INJECTION OF SYSTEMICS TO SUPPRESS SEED AND CONE INSECTS IN DOUGLAS FIR IN MONTANA,

1985 ◽  
Vol 117 (8) ◽  
pp. 961-969 ◽  
Author(s):  
R.C. Reardon ◽  
L.J. Barrett ◽  
T.W. Koerber ◽  
L.E. Stipe ◽  
J.E. Dewey
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seed Yield ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Systemic Insecticides ◽  
Filled Seeds

AbstractThe systemic insecticides oxydemeton-methyl and acephate were injected at 10- and 15-cm spacings, and acephate and dimethoate were implanted at 10-cm spacing in Douglas fir, Pseudotsuga menziesii var. glauca (Beissn.) Franco, to improve seed yield. Nutrients were also injected at 15-cm spacing. All treatments except nutrients and dimethoate increased the yield of filled seeds when compared with the checks. The western spruce budworm, Choristoneura occidentalis Freeman, and spruce coneworm, Dioryctria reniculelloides Mutuura and Munroe, caused most of the damage to cones.

NUMBER AND SIZE OF EGGS IN EGG MASSES OF THE WESTERN SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

1984 ◽  
Vol 116 (5) ◽  
pp. 657-661 ◽  
Author(s):  
Robert W. Campbell ◽  
Torolf R. Torgersen ◽  
Nilima Srivastava
Keyword(s):  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Egg Masses ◽  
Single Row

AbstractFoliage of Douglas-fir and grand fir bearing egg masses of the western spruce budworm, Choristoneura occidentalis Freeman, was collected from sites in Oregon, Idaho, and Montana. Later, 4154 of these egg masses were examined in the laboratory. The average number of eggs per mass was 47.5 ± 10.65 (range 23–58). The number of eggs in a mass increased as defoliation of current foliage increased from none to moderate. The average number of eggs per linear millimeter of a single row ranged among sites from 1.24 ± 0.02 to 2.43 ± 0.21. The average number of eggs per linear millimeter of a row was highest (1.99) among the sites studied in Idaho, and lowest (1.58) among the sites studied in Oregon.

ANTS PREYING ON PUPAE OF THE WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALIS (LEPIDOPTERA: TORTRICIDAE), IN EASTERN OREGON AND WESTERN MONTANA

1984 ◽  
Vol 116 (12) ◽  
pp. 1665-1669 ◽  
Author(s):  
Lorna C. Youngs ◽  
Robert W. Campbell
Keyword(s):  
Spruce Budworm ◽  
Western Montana ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Formica Obscuripes

AbstractIn 1981 and 1982, the following ant species and numbers were detected preying on pupae of the western spruce budworm, Choristoneura occidentalis Freeman, in eastern Oregon and western Montana: Formica obscuripes Forel, 174; Camponotus modoc Wheeler, 160; C. laevigatus Smith, 53; C. vicinus Mayr, 48; F. podzolica Francoeur, 43; F. accreta Francoeur, 32; F. neorufibarbis Emery, 12; F. lasioides Emery, 1; and Formica sp. (microgyna group). The Camponotus species and F. obscuripes were detected preying on budworm on one-third or more of the trees they foraged.

Timing of Trunk-Implanted Acephate for Protection of Douglas-Fir from Defoliation by the Western Spruce Budworm

1988 ◽  
Vol 3 (4) ◽  
pp. 126-128 ◽  
Author(s):  
Thomas W. Koerber ◽  
Roger E. Sandquist
Keyword(s):  
Pseudotsuga Menziesii ◽  
Spruce Budworm ◽  
Weather Conditions ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm ◽  
Defoliation Treatment ◽  
Favorable Weather

Abstract The effectiveness of implanting acephate in boles of superior Douglas-fir (Pseudotsuga menziesii var. glauca) to protect them from defoliation by western spruce budworm (Choristoneura occidentalis) and spruce cone-worm (Dioryctria reniculelloides) was investigated. April treatment afforded greater foliage protection than May treatment. November treatment was as effective as April in protecting trees from defoliation. Treatment in fall would be more efficient than in spring because of better road access and more favorable weather conditions. West. J. Appl. For. 3(4):126-128, October 1988.

Multicentury history of western spruce budworm outbreaks in interior Douglas-fir forests near Kamloops, British Columbia

2006 ◽  
Vol 36 (7) ◽  
pp. 1758-1769 ◽  
Author(s):  
Rochelle Campbell ◽  
Dan J Smith ◽  
André Arsenault
Keyword(s):  
British Columbia ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Survival Rates ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Western Spruce Budworm ◽  
Air Temperatures ◽  
Forest Sites ◽  
History Of

Western spruce budworm (Choristoneura occidentalis Freeman) is a native defoliator of forests in the interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) forests of British Columbia, Canada. Dendrochronological techniques and the software program OUTBREAK were used to reconstruct a defoliation history of Douglas-fir for 19 forest sites near Kamloops in central British Columbia. By comparing the radial-growth response of ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) with that of Douglas-fir growing in nearby but separate stands, eight western spruce budworm outbreaks over the past 300 years were distinguished. Although there is considerable variation in the timing and duration of these western spruce budworm events at the stand level, synchronous outbreaks have occurred in approximately 30- to 43-year cycles. Spectral analyses of a composite time series from all stands showed similar and consistent intervals between outbreaks. Climatic variation appears to have been important to budworm outbreaks in the 20th century. Notable outbreaks tended to occur during years with average spring air temperatures following winters with less than average precipitation. Based on this finding, it is proposed that with high over-winter survival rates and a longer growing season, the duration of outbreaks may increase in the future.

Western Spruce Budworm Damage to Sprayed and Unsprayed Young Douglas-Fir

1988 ◽  
Vol 3 (2) ◽  
pp. 44-46 ◽  
Author(s):  
Rene I. Alfaro ◽  
Emil Wegwitz
Keyword(s):  
British Columbia ◽  
Regression Model ◽  
Pseudotsuga Menziesii ◽  
Tree Mortality ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm

Abstract Defoliation, mortality, and top-kill were measured in 40-year-old, open-grown Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) under attack by the western spruce budworm (Choristoneura occidentalis [Freeman]) in the interior of British Columbia, in control trees and trees treated with ground sprays of the insecticide Sevin. In untreated trees that sustained repeated defoliation of 50 to 90% of the total crown foliage, tree mortality began after four years and had reached 29% after eight years. Thirty-four percent of the survivors in this group suffered top-kill, which averaged 1.0 m at the end of eight years. No mortality and only negligible top-kill occurred in trees, sprayed or not, which sustained less than 50% defoliation. A regression model of the probability of tree mortality based on the defoliation is presented. West. J. Appl. For. 3(2):44-46, April 1988.

THIODICARB AND SULPROPHOS APPLIED TO WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALIS (LEPIDOPTERA: TORTRICIDAE), WITH AN AERIAL SPRAY SIMULATOR

1983 ◽  
Vol 115 (4) ◽  
pp. 357-359
Author(s):  
Charles E. Richmond
Keyword(s):  
Pseudotsuga Menziesii ◽  
Large Scale ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Mortality Level ◽  
Western Spruce Budworm

AbstractThiodicarb and sulprophos were applied to western spruce budworm, Choristoneura occidentalis Freeman, which were infesting small Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco. An aerial spray simulator was used for this application at three dosages. At 105 and 160 g a.i./ha, thiodicarb reduced the number of larvae/100 buds by at least 90%. Sulprophos failed to achieve the target mortality level of 90% or better, even at the highest dosage tested—at 380 g a.i./ha sulprophos reduced the number of larvae/100 buds by 74%. Thiodicarb appears to be the better candidate for future large-scale aerial tests.

Sign in / Sign up

Export Citation Format

Share Document