PEST MANAGEMENT OF DOUGLAS-FIR TUSSOCK MOTH: ESTIMATING LARVAL DENSITY BY SEQUENTIAL SAMPLING

1985 ◽  
Vol 117 (9) ◽  
pp. 1111-1115 ◽  
Author(s):  
R.F. Shepherd
Keyword(s):  
Pest Management ◽  
Sequential Sampling ◽  
Larval Density ◽  
Critical Density ◽  
Douglas Fir ◽  
Density Level ◽  
Sampling System ◽  
Tussock Moth ◽  
Early Instar ◽  
The Relationship

AbstractA sequential sampling system for early-instar Douglas-fir tussock moth larvae based on beating 3 lower branches from each of a number of trees is described. The relationship between lower- and mid-crown insect densities is given. The number of samples required to assess moderate insect densities using a fixed level of precision and at low insect densities using a critical density level is presented. The system is designed to be used during the early stages of an outbreak in stands not previously defoliated.

POPULATION CHANGE IN AN OUTBREAK OF THE DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE), IN CENTRAL ARIZONA

1974 ◽  
Vol 106 (11) ◽  
pp. 1171-1174 ◽  
Author(s):  
Richard R. Mason
Keyword(s):  
Population Density ◽  
Population Change ◽  
Larval Density ◽  
Douglas Fir ◽  
First Year ◽  
Tussock Moth ◽  
The Third ◽  
Orgyia Pseudotsugata ◽  
Early Instar ◽  
Central Arizona

AbstractChanges in population density were evaluated over an outbreak cycle of the Douglas-fir tussock moth. Growth rate of populations was independent of larval density in the first year, but thereafter became a reciprocal function of density, terminated by complete population collapse at the end of the third year. Through correlation analyses, it was found that density of small larvae accounted for a large proportion of the change in population density between years. This suggests that the local infestations developed largely from resident populations of at least 2 years and not from spread of early instar larvae during the outbreak.

PEST MANAGEMENT OF DOUGLAS-FIR TUSSOCK MOTH (LEPIDOPTERA: LYMANTRIIDAE): A SEQUENTIAL SAMPLING METHOD TO DETERMINE EGG MASS DENSITY

1984 ◽  
Vol 116 (7) ◽  
pp. 1041-1049 ◽  
Author(s):  
R. F. Shepherd ◽  
I. S. Otvos ◽  
R. J. Chorney
Keyword(s):  
Sampling Method ◽  
Mass Density ◽  
Sequential Sampling ◽  
Douglas Fir ◽  
Egg Mass ◽  
Tussock Moth ◽  
Incipient Stage ◽  
Orgyia Pseudotsugata ◽  
Detection Tool ◽  
Variability Data

AbstractA sequential egg-mass sample system for Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough (Lepidoptera: Lymantriidae), was designed, based on visual scanning of the lower branches of Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco. A branch was removed from each quadrant from the upper, middle and lower crown level, and from the lowest whorl of a total of 59 non-defoliated trees in 10 areas. No consistent trend in egg-mass density per branch could be found between crown levels and no level proved superior as a representative of the tree. Therefore, the lower whorl of branches was selected for survey purposes because of sampling efficiency. Sample stop lines were determined from egg-mass density and variability data collected on 55 sites and subsequent defoliation estimates were related to these densities. The system is designed as an early detection tool to be used only in non-defoliated stands at the incipient stage of an impending outbreak.

DEVELOPMENT OF SAMPLING METHODS FOR THE DOUGLAS-FIR TUSSOCK MOTH, HEMEROCAMPA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE)

1970 ◽  
Vol 102 (7) ◽  
pp. 836-845 ◽  
Author(s):  
Richard R. Mason
Keyword(s):  
Sampling Methods ◽  
Larval Density ◽  
Douglas Fir ◽  
Tree Crown ◽  
Moth Population ◽  
Tussock Moth ◽  
Egg Density ◽  
Standardize Sampling ◽  
Eggs And Larvae ◽  
Different Parts

AbstractMethods were developed to standardize sampling of the Douglas-fir tussock moth. Population density was estimated in terms of the number of eggs or larvae per 1,000 sq. in. of branch area of Abies concolor (Gord. and Glend.) Lindl. The density of eggs and larvae varied significantly in different parts of the tree crown. In an outbreak, egg masses were concentrated on inside branches near the bottom of the crown, but in light populations they were most common on outside branches in the top of the crown. Larvae were found over the entire tree, but they were especially concentrated on foliage in the top. Mean density of larvae in the middle crown was representative of the whole tree. Egg density is estimated from whole branches sampled representatively from three crown levels; however, density of larvae is estimated accurately from 17-in. twig samples taken from just the middle crown. Because eggs are clumped in masses and larvae are dispersed over the foliage, larval density can be estimated with much less sampling than can egg density for the same precision.

COMPARISON OF ARTIFICIAL PUPATION SHELTERS AND OTHER MONITORING METHODS FOR ENDEMIC POPULATIONS OF DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (MCDUNNOUGH) (LEPIDOPTERA: LYMANTRIIDAE)

1992 ◽  
Vol 124 (2) ◽  
pp. 359-369 ◽  
Author(s):  
D.L. Dahlsten ◽  
D.L. Rowney ◽  
W.A. Copper ◽  
J.M. Wenz
Keyword(s):  
General Trend ◽  
Larval Density ◽  
Douglas Fir ◽  
Monitoring Methods ◽  
Larval Population ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Pheromone Trapping ◽  
Adult Sex Ratio ◽  
Early Predictor

AbstractTwo artificial pupation shelter types were compared as Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), monitoring methods in El Dorado County, CA. No difference in attraction was found; wood shelters are recommended as they are both inexpensive and durable. Shelters were compared with three-crown-level larval sampling and with pheromone trapping. Cocoon counts from shelters were significantly correlated with same-year larval density, reflecting larval sample differences between ridges and the general trend in plots along ridges. Egg masses from shelters in 1978 were significantly correlated with the next year’s larval counts, and are of potential value as an early predictor of larval population. The shelter method also provides information on adult sex ratio and pupal and egg emergence, parasitism, and predation.

REGRESSION FOR ESTIMATING NUMBER OF DOUGLAS-FIR TUSSOCK MOTH EGGS RELATIVE TO EGG MASS WEIGHT

1978 ◽  
Vol 110 (2) ◽  
pp. 131-134
Author(s):  
Roy C. Beckwith ◽  
R. R. Mason ◽  
H. G. Paul
Keyword(s):  
Douglas Fir ◽  
Regression Equation ◽  
Sampling Scheme ◽  
Egg Mass ◽  
Tussock Moth ◽  
Early Instar

AbstractA common regression equation, representing data collected from four widely separated areas, was constructed to determine number of eggs of the Douglas-fir tussock moth based on individual egg mass weights. The regression is designed for use in any egg mass sampling scheme where a knowledge of the potential early instar population is required. The regression equation is also given for each area.

ACTIVITY RHYTHMS OF LEPIDOPTEROUS DEFOLIATORS: III. THE DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (McDUNNOUGH) (LIPARIDAE)

1965 ◽  
Vol 43 (5) ◽  
pp. 673-681 ◽  
Author(s):  
D. K. Edwards
Keyword(s):  
Adult Emergence ◽  
Douglas Fir ◽  
Nocturnal Activity ◽  
Late Afternoon ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Adaptive Value ◽  
Temperature Regimes ◽  
Late Instar ◽  
Early Instar

Techniques previously described were used to record larval activity on foliage and adult emergence and flight times of Orgyia pseudotsugata (McDunnough) in both constant and naturally varying temperatures. Most larvae hatched in the morning after sunrise; hatching decreased during the day and was minimal at night. Early-instar larvae were active during the day in all temperature regimes studied, and nocturnal activity occurred only when the temperature was at least 20 °C. Young larvae tended to drop from foliage on silken threads with dropping peaks in the morning and afternoon. Late-instar larvae were mainly nocturnal in the constant and varying temperatures. Adult emergence, and flight of males, occurred mainly in late afternoon prior to sunset, and evidence of heightened activity at this same time in the diel was discernible as early as the first and second instars. The possible adaptive value of these rhythms in the insects in nature is discussed.

DISTRIBUTION OF BARBARA COLFAXIANA (KEARFOTT) (LEPIDOPTERA: TORTRICIDAE) EGGS WITHIN AND AMONG DOUGLAS-FIR CROWNS AND METHODS FOR ESTIMATING EGG DENSITIES

1989 ◽  
Vol 121 (7) ◽  
pp. 569-578 ◽  
Author(s):  
J.D. Sweeney ◽  
G.E. Miller
Keyword(s):  
Negative Binomial ◽  
Sequential Sampling ◽  
Critical Density ◽  
Optimal Number ◽  
Douglas Fir ◽  
Seed Orchards ◽  
Frequency Distributions ◽  
Seed Loss ◽  
Control Threshold ◽  
Egg Density

AbstractThe spatial and frequency distributions of Douglas-fir cone moth, Barbara colfaxiana (Kearfott), eggs in Douglas-fir trees and stands were determined by dissecting 13 262 conelets collected from 81 trees in three sites and 2 years. 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 three of five site-years but a common k for the negative binomial could not be calculated. Green’s index of aggregation suggested that the cone moth egg distribution was significantly aggregated in each site-year.The optimal number of conelets per tree to sample was determined to be four in forest stands and three 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 Kuno. The sample sizes required to estimate a control threshold density of 0.6 eggs per 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.

DAMAGE PREDICTION FOR CONTARINIA OREGONENSIS FOOTE (DIPTERA: CECIDOMYIIDAE) IN DOUGLAS-FIR SEED ORCHARDS

1986 ◽  
Vol 118 (12) ◽  
pp. 1297-1306 ◽  
Author(s):  
G.E. Miller
Keyword(s):  
Sequential Sampling ◽  
Gall Midge ◽  
Critical Density ◽  
Sampling Technique ◽  
Average Density ◽  
Douglas Fir ◽  
Damage Prediction ◽  
The Mean ◽  
Optimum Sample ◽  
Filled Seeds

AbstractDamage at cone harvest by the Douglas-fir cone gall midge, Contarinia oregonensis Foote, was positively correlated with the number of egg-infested scales per conelet in the spring. Reducing the average number of galled seeds per cone by 1.5 increased the average number of filled seeds per cone by 1.0 in insecticide trials. Optimum sample sizes for estimating average densities of egg-infested scales were calculated to be one conelet per tree and 150 trees per orchard. The mean crowding variable was linearly related to average density so a sequential sampling technique relative to a critical density, using Iwao’s procedure, was developed for determining the need of control actions.

PEST MANAGEMENT OF DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE): MONITORING ENDEMIC POPULATIONS WITH PHEROMONE TRAPS TO DETECT INCIPIENT OUTBREAKS

1985 ◽  
Vol 117 (7) ◽  
pp. 839-848 ◽  
Author(s):  
R.F. Shepherd ◽  
T.G. Gray ◽  
R.J. Chorney ◽  
G.E. Daterman
Keyword(s):  
Pest Management ◽  
Mass Density ◽  
Douglas Fir ◽  
Population Cycle ◽  
Poor Correlation ◽  
Egg Mass ◽  
Pheromone Traps ◽  
Threshold Density ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata

AbstractThe numbers of Douglas-fir tussock moths (Orgyia pseudotsugata) (Lepidoptera: Lymantriidae) caught in sticky, delta-shaped pheromone traps baited with different concentrations of synthetic lures were compared with egg-mass densities and subsequent defoliation throughout a population cycle. A lure containing 0.01% pheromone by weight in the form of a 3 × 5-mm polyvinylchloride rod provided more consistent catches than pheromone concentrations of 0.0001, 0.001, 0.1, or 1.0%. Trap saturation occurred when >40 moths per trap were caught. To achieve a standard error of 30%, 6 traps were required at each site. There was a poor correlation between numbers of moths caught and egg-mass density or defoliation estimates in the following generation, but a threshold density was found that provides a warning of an incipient outbreak. Ground surveys for egg masses are recommended to confirm suspected infestations after continuous increases in moth catches for 2 to 3 years or if an average of 25 moths or more per trap has been caught.

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