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.

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.

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.

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.

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.

TOXICITY OF INSECTICIDES TO DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE): I. CONTACT AND FEEDING TOXICITY

1979 ◽  
Vol 111 (10) ◽  
pp. 1145-1159 ◽  
Author(s):  
Jacqueline L. Robertson ◽  
Lucille M. Boelter
Keyword(s):  
Rhodamine B ◽  
Douglas Fir ◽  
Relative Toxicity ◽  
Spray Chamber ◽  
Population Response ◽  
Larval Stages ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Rhodamine B Dye ◽  
Spray Volume

AbstractThe toxicities of 14 insecticides to selected larval stages of the Douglas-fir tussock moth were determined with a laboratory spray chamber. The toxicities of 10 were also determined in feeding bioassays. Younger instars were, in general, more susceptible to the toxicants. Significant differences in population response from 1973 to 1977 precluded a rigid interpretation of relative toxicity values in relation to the standard for comparison, DDT. Spray volume, formulation, and the presence of rhodamine B dye significantly affected toxicities of two of the materials, carbaryl and trichlorfon. The degree of exposure of larvae to bioethanomethrin and carbaryl significantly affected mortality.

THE EFFECT OF TEMPERATURE AND FOOD DEPRIVATION ON SURVIVAL OF FIRST-INSTAR DOUGLAS-FIR TUSSOCK MOTHS (ORGYIA PSEUDOTSUGATA) (LEPIDOPTERA: LYMANTRIIDAE)

1983 ◽  
Vol 115 (6) ◽  
pp. 663-666 ◽  
Author(s):  
Roy C. Beckwith
Keyword(s):  
Food Deprivation ◽  
Larval Survival ◽  
Douglas Fir ◽  
Effect Of Temperature ◽  
Rearing Temperature ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
First Instar ◽  
Starvation Conditions

AbstractMortality of neonatal Douglas-fir tussock moth larvae varied from 0% to 100% depending on the rearing temperature and duration of food deprivation. Lower temperatures apparently favor larval survival under starvation conditions. For each period of food deprivation, mortality occurs earlier as the temperature increases; this shift to earlier mortality was significant at P <.01. Some implications are discussed.

VARIATION IN RESPONSE TO INSECTICIDES BY DOUGLAS-FIR TUSSOCK MOTH, ORGYIA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE), POPULATIONS

1978 ◽  
Vol 110 (3) ◽  
pp. 325-328 ◽  
Author(s):  
Jacqueline L. Robertson ◽  
Lucille M. Boelter ◽  
Robert M. Russell ◽  
N. E. Savin
Keyword(s):  
Likelihood Ratio Test ◽  
Chemical Control ◽  
Douglas Fir ◽  
Ratio Test ◽  
Response Curves ◽  
Control Programs ◽  
Tussock Moth ◽  
Orgyia Pseudotsugata ◽  
Different Populations ◽  
Successive Generations

AbstractSelected insecticides were topically applied to different populations of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough). For each insecticide, the hypothesis of equal response curves was rejected by the likelihood ratio test. Even for two successive generations of the same populations, the hypothesis of equality was not accepted for some insecticides. Chemical control programs directed at different populations of this insect may be adversely affected by such variations.

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