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.

Stand response to western spruce budworm and Douglas-fir bark beetle outbreaks, Colorado Front Range

1993 ◽  
Vol 23 (3) ◽  
pp. 479-491 ◽  
Author(s):  
Keith S. Hadley ◽  
Thomas T. Veblen
Keyword(s):  
Bark Beetle ◽  
Stand Structure ◽  
Fire Suppression ◽  
Rocky Mountain ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Colorado Front Range ◽  
Front Range ◽  
Western Spruce Budworm ◽  
Wide Range

The montane forests (i.e., below ca. 2900 m) of the Colorado Front Range have experienced repeated outbreaks of western spruce budworm (Choristoneuraoccidentalis Free.) and Douglas-fir bark beetle (Dendroctonuspseudotsugae Hopk.), both of which locally attack Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). In this study we examine the effects of historically documented outbreaks of these insects on succession, stand structure, and radial growth of host and nonhost species in Rocky Mountain National Park. The most recent budworm (1974–1985) and bark beetle (1984–present) outbreaks resulted in the most severe and widespread disturbance of these forests since the late 1800s. Stand response to these outbreaks is primarily a function of stand structure and age characteristics of Douglas-fir prior to an outbreak. Young, vigorous postfire stands show minimal budworm defoliation, and in these stands only remnant trees from the prefire generation appear susceptible to beetle-caused mortality. Dense stands exhibit higher budworm-induced mortality, which hastens the natural thinning process and shifts dominance towards the nonhost species. The stands most severely disturbed by the combined insect agents are multistoried stands with high host densities and a wide range of stem sizes. The stand response to these disturbances include the growth release of shade-intolerant, seral species, and in some cases, a higher survivorship among midsized individuals of the host Douglas-fir. The net result of the combined insect outbreaks is the temporary slowing of the successional trend towards a steady-state Douglas-fir forest. Fire suppression, by increasing the density of suppressed Douglas-fir, has previously been shown to favor increased outbreak severity of western spruce budworm in the northern Rockies. However, in the Front Range, recent increases in outbreak severity and their synchroneity may also be the result of large areas of forest, burned during the late 19th century during European settlement, simultaneously entering structural stages susceptible to insect outbreak.

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.

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.

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.

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.

PROTECTION OF DOUGLAS-FIR FOLIAGE FROM WESTERN SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) DAMAGE BY EARLY APPLICATIONS OF ACEPHATE (ORTHENE 75S)

1978 ◽  
Vol 110 (11) ◽  
pp. 1127-1132 ◽  
Author(s):  
Charles E. Richmond ◽  
Robert D. Averill ◽  
Carl E. Crisp
Keyword(s):  
Liquid Chromatography ◽  
Pseudotsuga Menziesii ◽  
Active Metabolite ◽  
Spruce Budworm ◽  
Significant Degree ◽  
Douglas Fir ◽  
Gas Liquid Chromatography ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm

AbstractAcephate (Orthene 75S) was applied to Douglas-fir (Pseudotsuga menziesii Mirbl. [Franco]) in spring 1976 to determine its efficacy for protecting current year’s foliage from western spruce budworm (Choristoneura occidentalis Freeman). Results showed budworm mortality for both treatments exceeded the checks by at least 91% at all sample periods. A significant degree of foliage protection was also achieved as measured by mean twig length and mean number of missing needles per twig. Samples of new growth were analyzed for residues of acephate and methamidophos (an active metabolite of acephate) by gas-liquid chromatography. Results showed that high levels of insecticide persisted for about 10 days, then dropped over a 5-day period to lower levels for the rest of the study, about 35 days.

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