RELATIONSHIPS BETWEEN DIFFERENT SAMPLING PROCEDURES FOR THE GYPSY MOTH, PORTHETRIA DISPAR (LEPIDOPTERA: LYMANTRIIDAE) AND ITS NATURAL ENEMIES

1974 ◽  
Vol 106 (3) ◽  
pp. 225-231 ◽  
Author(s):  
Ronald M. Weseloh
Keyword(s):  
Gypsy Moth ◽  
Natural Enemies ◽  
Sampling Methods ◽  
Egg Mass ◽  
Regression Analyses ◽  
Field Sampling ◽  
Tree Defoliation ◽  
Porthetria Dispar ◽  
Sampling Procedures ◽  
Adult Abundance

AbstractA variety of field sampling procedures were used to estimate population levels of the gypsy moth, Porthetria dispar (L.) (Lepidoptera: Lymantriidae), and the following natural enemies: Apanteles melanoscelus (Ratzeburg) (Hymenoptera: Braconidae), Blepharipa scutellata (Robineau-Desvoidy) (Diptera: Tachinidae), and Calosoma sycophanta (L.) (Coleoptera: Carabidae). Regression analyses indicated, among other things, that gypsy moth egg mass counts were not good indicators of tree defoliation, but that defoliation and number of gypsy moth larvae on branch terminals were correlated. Estimates of adult abundance of A. melanoscelus and B. scutellata were negatively correlated with estimates of numbers of immature parasitoids. Numbers of gypsy moth larvae parasitized by A. melanoscelus were positively correlated with numbers of A. melanoscelus cocoons sampled. Numbers of adult C. sycophanta were not correlated with larval numbers of this insect. It was concluded from these results that the procedures used to estimate numbers of natural enemy adults were not entirely adequate, but may be useful for supplementing other sampling methods.

DEVELOPMENT AND EVALUATION OF A SAMPLING SCHEME FOR THE GYPSY MOTH EGG PARASITOID OOENCYRTUS KUVANAE (HYMENOPTERA: ENCYRTIDAE)

1981 ◽  
Vol 113 (7) ◽  
pp. 575-584 ◽  
Author(s):  
M. W. Brown ◽  
James L. Rosenberger ◽  
E. Alan Cameron
Keyword(s):  
Gypsy Moth ◽  
Negative Binomial ◽  
Sampling Methods ◽  
Field Evaluation ◽  
Egg Parasitoid ◽  
Sampling Scheme ◽  
Egg Mass ◽  
Egg Masses ◽  
Coefficients Of Variation ◽  
Ooencyrtus Kuvanae

AbstractFour sampling methods for Ooencyrtus kuvanae (Howard) populations were compared for efficiency using coefficients of variation. On this basis, none of the sampling methods was uniformly superior to any other, but a cluster of 0.01 ha subplots was chosen as the best method because of the aggregation of both gypsy moth egg masses and parasitoids. From the estimated population variance per egg mass it was calculated that 150 egg masses should be sampled per plot to provide an error bound of 0.2 parasitoid per egg mass (α = 0.1). An analysis of variance indicated that variation among study areas was the largest source of variation, and that among day, within day, and plot configuration variation were significant. Estimates of parasitoid activity are most reliable during the period between 1300 and 1600 h EST. Activity of parasitoids was reduced on overcast days. In August, the distribution of O. kuvanae approximates that of the negative binomial but with too many individuals in the high frequency classes. In a compromise between cost and accuracy, the sampling scheme selected consists of thirty 0.01 ha subplots per plot sampled between 1300 and 1600 h EST on sunny days. This sampling scheme was found satisfactory using field evaluation.

The Role of Disease and Desiccation in the Population Dynamics of the Gypsy Moth Porthetria dispar (L.) (Lepidoptera: Lymantriidae)

1963 ◽  
Vol 95 (4) ◽  
pp. 426-434 ◽  
Author(s):  
Robert W. Campbell
Keyword(s):  
New York ◽  
Population Dynamics ◽  
Gypsy Moth ◽  
Disease Incidence ◽  
Egg Mass ◽  
Population Reduction ◽  
Porthetria Dispar ◽  
Insect Density ◽  
The Town

AbstractThe population dynamics of the gypsy moth, Porthetria dispar (L.), are being studied on 10 sites in the Town of Glenville, New York. This paper discusses the role of disease and a condition here termed “desiccation” in the dynamics of these populations during a 4-year period, 1958-1961 inclusive.The term “desiccation” refers to dead pre-pupae that appeared shriveled, and were stiff to the touch, and which had a solid mass of food in their gut. The incidence of desiccation among pre-pupae was closely related to the number of eggs per egg mass produced at the end of the generation (a measure of relative insect density).Disease incidence among larval gypsy moth populations was directly related to insect density. Disease incidence was also related to site conditions, with higher mortality occurring in wet sites.When larval populations reached high densities, they always declined from the dense level within a few generations. These declines ranged from a sudden drastic reduction to a much more gradual decline. The former was preceded by virtual food exhaustion, while the latter was not usually preceded by exhaustion of the food supply.Disease and desiccation were primary factors in producing the sudden type of population reduction noted above. Pathogens may also play an important part in the more gradual type of decline, but this point remains to be clarified.

scholarly journals Cynipid gall growth dynamics and enemy attack: effects of gall size, toughness and thickness

1999 ◽  
Vol 28 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Geraldo W. Fernandes ◽  
Mário M. Espírito-Santo ◽  
Maurício L. Faria
Keyword(s):  
Multiple Regression ◽  
Wall Thickness ◽  
Natural Enemies ◽  
Growth Dynamics ◽  
Maturation Stage ◽  
Regression Analyses ◽  
The Third ◽  
Galling Insects

Galling insects have developed many strategies to preclude or reduce the attack by natural enemies, such as an increased wall thickness early in the season, and switching to larger and tougher walls later in the maturation stage. In this study, we observed the efficiency of each one of these parameters in reducing mortality of the leaf galling wasp Atrusca caprone Weld (Hymenoptera: Cynipidae), on Quercus turbinella Greene (Fagaceae), during the three months of gall development (June-August). Gall diameter and wall toughness increased from the first to the third month of the study (ANOVA, Diameter: F = 88.73, p < 0.0001; ANOVA, Toughness: F = 26.13, p < 0.0001). However, gall wall thickness increased from June to July, decreasing in August (ANOVA, F = 35.84, p < 0.0001). Gall survivorship was only 2 % in June, increasing to 10 % in July and to 29.3 % in August. Multiple regression analyses showed that only gall wall toughness influenced gall susceptibility to parasitoid attack (r² = 0.52, F = 13.84, p < 0.01). Gall survivorship was very low in the first month due probably to low wall toughness, which led to a higher success of oviposition by parasitoids during this phase. These results suggest that the first month is critical to gall establishment, and the galls which are not parasitized at this stage are less likely to be attacked later.

Experimental parasitization of larvae of the gypsy moth, Porthetria dispar (L.), with the entomogenous fungus, Beauveria bassiana (Balsamo) Vuill

Parasitology ◽  
1975 ◽  
Vol 70 (3) ◽  
pp. 341-346 ◽  
Author(s):  
S. S. Wasti ◽  
G. C. Hartmann
Keyword(s):  
Beauveria Bassiana ◽  
Gypsy Moth ◽  
Post Inoculation ◽  
Entomogenous Fungus ◽  
Porthetria Dispar ◽  
Host Penetration ◽  
Fungus Beauveria Bassiana ◽  
Wax Moth

Second-instar larvae of the gypsy moth, Porthetria dispar (L.) were infected with Beauveria bassiana (Balsamo) Vuill. by allowing larvae to crawl over sporulating cultures of the fungus. Virulence of the pathogen was increased by inoculating larvae of the wax moth, Galleria melonella (L.), twice in serial succession. Observations were made on the infectivity and histopathology of the parasite in the host. Penetration of the cuticle occurred 24 h after inoculation and at 64 h post-inoculation the interior was completely filled with hyphae. Penetration of the gut wall was also observed.

Planning programs to estimate salmon harvest with coded-wire tags

1998 ◽  
Vol 55 (8) ◽  
pp. 1983-1995 ◽  
Author(s):  
David R Bernard ◽  
Robert P Marshall ◽  
John E Clark
Keyword(s):  
Sampling Methods ◽  
Coho Salmon ◽  
Cost Functions ◽  
Commercial Fisheries ◽  
Sampling Strategies ◽  
Sample Sizes ◽  
Field Sampling ◽  
Tag Loss ◽  
Coded Wire Tags

Methods are presented for planning individual catch-sampling, tagging, and field-sampling programs to estimate salmon (Oncorhynchus spp.) harvest in recreational and commercial fisheries from several hatchery-produced and wild cohorts through recovery of coded-wire tags. We show how to determine sample sizes sufficiently large to detect harvest and link sample sizes to expenditures through linear and allometric cost functions to determine optimal tagging and catch-sampling rates. Sample sizes that will minimize bias and variance are charted for field-sampling programs designed to estimate the fraction of a cohort with tags. We describe sampling strategies that can be used to detect or to minimize bias in harvest estimates from tag loss, tag-induced mortality, tag-induced straying, and nonrandom sampling. Methods are demonstrated with data on cohorts of chinook (O. tshawytscha) and coho salmon (O. kisutch) from Alaska.

scholarly journals Effectiveness of Diflubenzuron and Bacillus thuringiensis Against Gypsy Moth Populations

1997 ◽  
Vol 14 (3) ◽  
pp. 135-140 ◽  
Author(s):  
Kevin W. Thorpe ◽  
Richard L. Ridgway ◽  
Ralph E. Webb
Keyword(s):  
Bacillus Thuringiensis ◽  
Population Density ◽  
Gypsy Moth ◽  
Mass Density ◽  
Larval Mortality ◽  
Larval Density ◽  
Egg Mass ◽  
Percent Reduction ◽  
Moth Population ◽  
Oak Trees

Abstract Aerial applications of Bacillus thuringiensis Berliner subsp. kurstaki (74.1 billion international units/ha per application; single and double applications), diflubenzuron [69 g (ai)/ha], and no treatment were evaluated. Treatment effects were estimated from frass collections, defoliation, counts of pupae under burlap, and egg-mass counts. Estimates of larval density in the canopy 20 days after treatment ranged from 318.3 to 55.5 larvae per m² in the control- and diflubenzuron-treated plots, respectively. Larval density was reduced in all treatments, and was lowest in the plots treated with diflubenzuron and two applications of B. thuringiensis. Population density rapidly declined in the control plots, and by June 20, when larvae were predominantly in the fifth and sixth instars, no significant differences in larval density were detected among the treatments. Significantly less defoliation occurred to oak trees in the treated plots, but no differences were detected among the spray treatments. Counts of pupae under burlap, postseason egg-mass counts, and percent reduction in egg-mass density did not differ significantly among treatments or versus controls. These results suggest that diflubenzuron and double B. thuringiensis treatments caused higher levels of larval mortality than occurred with a single B. thuringiensis application, but that with a naturally declining gypsy moth population the final levels of damage were the same under all treatments. North. J. Appl. 14(3):135-140.

scholarly journals A Comparison of Three Field Sampling Methods to Estimate Soil Carbon Content

2012 ◽  
Vol 58 (5) ◽  
pp. 513-522 ◽  
Author(s):  
Luke Worsham ◽  
Daniel Markewitz ◽  
Nathan P. Nibbelink ◽  
Larry T. West
Keyword(s):  
Carbon Content ◽  
Soil Carbon ◽  
Sampling Methods ◽  
Field Sampling ◽  
Soil Carbon Content
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