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.

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.

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: 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.

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.

DOUGLAS-FIR TUSSOCK MOTH (HEMEROCAMPA PSEUDOTSUGATA) EGG-MASS DISTRIBUTION ON WHITE FIR IN NORTHEASTERN CALIFORNIA

1967 ◽  
Vol 99 (11) ◽  
pp. 1193-1203 ◽  
Author(s):  
Robert F. Luck ◽  
Donald L. Dahlsten
Keyword(s):  
Sampling Method ◽  
Douglas Fir ◽  
Egg Mass ◽  
Egg Masses ◽  
Sample Unit ◽  
Tussock Moth ◽  
White Fir ◽  
Cardinal Direction ◽  
Sources Of Variation ◽  
Cardinal Directions

AbstractThe distribution of Douglas-fir tussock moth (Hemerocampa pseudotsugata McD.) egg-masses on white fir (Abies concolor (Gord. and Glend.) Lindl.) was studied in three areas of northern California. In each area 100 trees between 4.5 and 8.4 in. in diameter were stratified into five defoliation classes and four crown classes, giving a total of 20 classes per study area with five trees per class. Trees were divided into four crown levels and samples were taken at each of the cardinal directions at each level. Two branches comprised n sample unit in the top half of the tree (eight branches per level) and one branch the sample unit in the bottom half of the tree (four branches per level). Egg masses were recorded per 10 sq. ft of foliage or branch area. Eighty per cent or more of the egg masses were found in the bottom half of the crown. This percentage in the bottom half of the crown increased on trees with heavy defoliation or with increased exposure of the crown. Of the four possible sources of variation considered in this study, crown level, defoliation class, and crown class were significant while cardinal direction was not. A sampling method is proposed on the basis of the information gathered in this investigation.

PARASITOIDS AND PREDATORS OF THE DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIDAE), IN LOW TO MODERATE POPULATIONS IN CENTRAL CALIFORNIA

1977 ◽  
Vol 109 (5) ◽  
pp. 727-746 ◽  
Author(s):  
D. L. Dahlsten ◽  
R. F. Luck ◽  
E. I. Schlinger ◽  
J. M. Wenz ◽  
W. A. Copper
Keyword(s):  
Sierra Nevada ◽  
Egg Parasitoid ◽  
Host Population ◽  
Douglas Fir ◽  
Egg Mass ◽  
Moth Population ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
White Fir ◽  
Pupal Parasitoids

AbstractDouglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), populations were studied on white fir at four areas in central Sierra Nevada mountains of California during 1971–73. Life tables were constructed for four populations in El Dorado County. The number of eggs per egg mass decreased and the percentage eggs parasitized doubled with declining moth populations. Hymenopterous parasitoids were collected from all immature stages of the moth: one egg parasitoid, Telenomus californicus Ashmead, six species of larval parasitoids, principally, Hyposoter sp., and 13 species of larval–pupal parasitoids. Tachinids were predominant and accounted for 73% of the parasitoidism of the cocoons in 1971. The apparent mortality of female pupae due to the parasitoid complex was greater than 97% in 1971 and 75% in 1972. One population in Placer County collapsed in 1971 apparently due to a combination of heat exhaustion and low levels of virus infection. Other defoliators, spiders, and several predatory insect species were collected from the foliage samples simultaneously with the tussock moth during larval sampling. Twelve species of "free living" spiders which could be capable of preying on the defoliator complex of white fir were collected. Parasitoids and predators appear to be potentially important biotic factors at low to moderate host population levels. This is the first recorded case where an agent other than the nucleopolyhedrosis virus has been responsible for the collapse of a Douglas-fir tussock moth population.

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.

AERIAL APPLICATION OF NUCLEAR POLYHEDROSIS VIRUS AGAINST DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (McDUNNOUGH) (LEPIDOPTERA: LYMANTRIIDAE): I. IMPACT IN THE YEAR OF APPLICATION

1987 ◽  
Vol 119 (7-8) ◽  
pp. 697-706 ◽  
Author(s):  
I.S. Otvos ◽  
J.C. Cunningham ◽  
L.M. Friskie
Keyword(s):  
Nuclear Polyhedrosis Virus ◽  
Mass Density ◽  
Adult Emergence ◽  
Douglas Fir ◽  
Egg Mass ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Population Reduction ◽  
Polyhedrosis Virus ◽  
Nuclear Polyhedrosis

AbstractFour 10-ha plots located in Kamloops Forest District, British Columbia, containing Douglas-fir trees infested with Douglas-fir tussock moth were aerially sprayed with nuclear polyhedrosis virus (Virtuss) in 1982 when most larvae were in the first instar. A dosage of 2.5 × 1011 polyhedral inclusion bodies (PIB) per hectare was applied in an emulsifiable oil tank mix to one plot and the same dosage in an aqueous tank mix containing molasses was applied to a second plot. The remaining two plots were treated with dosages of 8.3 × 1010 and 1.6 × 1010 PIB per hectare, respectively, in the oil mix. The treatments were applied with a fixed-wing aircraft fitted with boom and nozzle equipment and calibrated to deliver 9.4 L/ha. A further four plots were selected as checks.Population reduction at 6 weeks post-spray (calculated using a modified Abbott’s formula) was 65% in the plot receiving the lowest dosage and from 87 to 95% in the remaining three plots. Incidence of virus infection, determined microscopically, peaked at 5–6 weeks post-spray with 85–100% of the larvae scored as positive. Levels of naturally occurring virus remained low in the check plots. Adult emergence from the pupae collected in the treated plots ranged from 4 to 19% and from 28 to 43% in the check plots. Reduction in egg-mass density attributed to the treatments was 97% in one plot, 99% in two others, and not determined for the fourth.A virus dosage of 8.3 × 1010 PIB per hectare, which is one-third of the previously recommended dosage, is adequate, and either tank mix is acceptable.

Surveying for Douglas-Fir Tussock Moth with Pheromone

1977 ◽  
Vol 23 (3) ◽  
pp. 172-174
Author(s):  
R. L. Livingston ◽  
G. Daterman
Keyword(s):  
Douglas Fir ◽  
Tussock Moth
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