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.

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.

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.

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 CYCLES OF THE DOUGLAS-FIR TUSSOCK MOTH (LEPIDOPTERA: LYMANTRIIDAE): THE TIME-DELAY HYPOTHESIS

1978 ◽  
Vol 110 (5) ◽  
pp. 513-518 ◽  
Author(s):  
Alan A. Berryman
Keyword(s):  
Time Delay ◽  
Negative Feedback ◽  
Population Model ◽  
Time Delays ◽  
Population Cycles ◽  
Douglas Fir ◽  
Limited Data ◽  
Moth Population ◽  
Density Dependent ◽  
Tussock Moth

AbstractA simple population model is used to test the hypothesis that Douglas-fir tussock moth population cycles are caused by time-delays in the responses of density-dependent (negative feedback) processes. The limited data that are available do not seriously conflict with this hypothesis.

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.

AERIAL APPLICATION OF NUCLEAR POLYHEDROSIS VIRUS AGAINST DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (McDUNNOUGH) (LEPIDOPTERA: LYMANTRIIDAE): II. IMPACT 1 AND 2 YEARS AFTER APPLICATION

1987 ◽  
Vol 119 (7-8) ◽  
pp. 707-715 ◽  
Author(s):  
I.S. Otvos ◽  
J.C. Cunningham ◽  
R.I. Alfaro
Keyword(s):  
Tree Mortality ◽  
Nuclear Polyhedrosis Virus ◽  
Douglas Fir ◽  
Aerial Application ◽  
Moth Population ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Polyhedrosis Virus ◽  
Nuclear Polyhedrosis ◽  
The Impact

AbstractFollowing aerial application of a Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), nuclear polyhedrosis virus (NPV) product called Virtuss on four plots in 1982, observations were made to determine the impact of these treatments in 1983 and 1984. Treated plots as well as buffer zones between and adjoining the treated plots, and three of the four check plots established in 1982, were monitored. The NPV appeared to have spread from the treated plots to adjoining areas in 1982, effectively reducing the Douglas-fir tussock moth population. This observation suggests that a strategy of spraying alternate swaths of Douglas-fir tussock moth infested stands with this viral insecticide may effectively initiate an epizootic that would control the population at a reduced cost.A naturally occurring NPV epizootic decimated the Douglas-fir tussock moth population in the three check plots in 1983, but severe tree mortality occurred in two of these plots with 60 and 62% of sample trees dead in 1984. Light tree mortality was noted in 1984 in two of the four treated plots with 4 and 7% of sample trees killed. It is concluded that the virus treatments in 1982 were successful in preventing tree mortality.

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

scholarly journals Impact of Biochar on Douglas-Fir Tussock Moth (Orgyia pseudotsugata Lepidoptera: Erebidae) Larvae Reared on Synthetic Die

Insects ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1065
Author(s):  
Stacey Rice-Marshall ◽  
Stephen P. Cook ◽  
John Randall
Keyword(s):  
Weight Gain ◽  
Larval Mortality ◽  
Douglas Fir ◽  
High Concentration ◽  
Larval Weight ◽  
Synthetic Diet ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Compensatory Feeding ◽  
Significant Difference

The use of biochar as a soil amendment in forest ecosystems can be beneficial in the restoration of degraded soils. Forest insects such as the Douglas-fir tussock moth, Orgyia pseudotsugata (McDonnough) (Lepidoptera: Erebidae), may be exposed to biochar when the material is applied. Two experiments were conducted using biochar either (1) applied to the surface of the diet at three rates (0, 5, and 10 mg) or (2) incorporated into synthetic diet at four rates (0, 10, 20, and 40% volume/volume). The objective of both experiments was to determine if biochar on the surface or incorporated into a synthetic diet affected development and survival of O. pseudotsugata larvae. In both experiments, there was a significant decrease in estimated time to larval mortality in all biochar treatments compared to untreated controls. In the surface-applied biochar experiment, there was a significant difference in larval weight gain at day 12 between the control and 10 mg biochar treatments. In the experiment with biochar incorporated into the diet, mean larval weight at day 12 was highest in the low (10%) biochar treatment compared to all other treatments, although weight gain was only significantly different between the low- and high-concentration (40%) biochar treatments. Our results suggest that larvae, feeding on a low amount of biochar in the synthetic diet, may respond by engaging in compensatory feeding behavior. Fewer surviving larvae in the biochar treatment groups may contribute to the lack of significance found in the comparison of weight gain at day 24 in each experiment.

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