INFLUENCE OF NATURAL DIETS AND LARVAL DENSITY ON GYPSY MOTH, LYMANTRIA DISPAR (LEPIDOPTERA: ORGYIIDAE), EGG MASS CHARACTERISTICS

1977 ◽  
Vol 109 (10) ◽  
pp. 1313-1318 ◽  
Author(s):  
John L. Capinera ◽  
Pedro Barbosa
Keyword(s):  
Gypsy Moth ◽  
Egg Size ◽  
Larval Density ◽  
Field Studies ◽  
Forest Composition ◽  
Egg Mass ◽  
Natural Diet ◽  
Egg Masses ◽  
Egg Number ◽  
Host Tree Species

AbstractLaboratory and field studies indicate that differences in gypsy moth egg mass characteristics can be related to larval density and natural diet. Egg mass characteristics are valuable indices of population quality as well as future population levels. Laboratory crowding reduced number of eggs/mass but did not affect egg size. Field collected egg masses from various population levels in Massachusetts also varied in egg number/mass, but egg size could not be directly correlated to density. Laboratory rearing of larvae on several natural diets produced differences in both egg number and size. Maple diets produced egg masses with fewer, smaller eggs, as compared with oak diets. Field collected egg masses also varied in mean egg size, according to host tree species. Thus, forest composition may directly affect the quality of gypsy moth populations, as well as numerical levels. Increasing density could affect egg size indirectly, by forcing gypsy moth larvae to feed on unfavorable host foliage.

Augmenting Nucleopolyhedrovirus Load in Gypsy Moth (Lepidoptera: Lymantriidae) Populations with Egg Mass Treatments

2003 ◽  
Vol 38 (2) ◽  
pp. 300-313 ◽  
Author(s):  
R. E. Webb ◽  
G. B. White ◽  
K. W. Thorpe
Keyword(s):  
Gypsy Moth ◽  
Early Treatment ◽  
Adult Emergence ◽  
Field Studies ◽  
Host Population ◽  
Egg Mass ◽  
Moth Population ◽  
Egg Masses ◽  
Entomophaga Maimaiga ◽  
Virus Dose

Previous observations show that gypsy moth, Lymantria dispar L., mortality induced by the fungus Entomophaga maimaiga Humber, Shimazu & Soper is quickly manifested as host population density increases. However, the gypsy moth nucleopolyhedrovirus (LdMNPV) lags behind the rebounding gypsy moth population. In this study, egg masses were contaminated with virus to successfully augment LdMNPV in gypsy moth populations in Virginia. Laboratory bioassays determined the approximate LdMNPV dose to apply to egg masses with and without the addition of the virus enhancer Blankophor BBH to the spray mixture. The highest dose of virus (5.3 × 105 PIBs/mL) tested without Blankophor BBH gave 82.3% mortality. Mortality for this virus dose increased to 91.8% when 1% Blankophor BBH was added. Field studies established that application of virus at an earlier date (04 April) was as efficacious as an application made at a later date (12 April); this study also included a further assessment of the addition of Blankophor BBH to the spray mixture. While application of LdMNPV + Blankophor BBH resulted in faster kill, levels of kill were similar (88.0% for early treatment and 78.8% for later treatment for virus applied alone versus 87.8% for early treatment and 89.1% for later treatment for virus + Blankophor BBH). However, a higher than expected number of cadavers in the LdMNPV + Blankophor BBH treatments had few or no polyhedral inclusion bodies (PIBs). Finally, virus infection resulting from the application of LdMNPV to pupae in June 1998 was compared with infection levels seen after the application of virus to egg masses in April 1999. The April 1999 treatment to egg masses clearly resulted in a higher kill of emerging larvae (=79.3% mortality) compared to the June 1998 treatment to female pupae (with virus incorporated into the egg masses laid by females after adult emergence) (=13.7% mortality). The virus was recovered season-long from larvae collected from populations in the treated plots (but not from control plots), indicating within season spread.

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.

The annual reproductive cycle of the black prickleback, Xiphister atropurpureus, a Pacific Coast blennioid fish

1974 ◽  
Vol 52 (7) ◽  
pp. 795-802 ◽  
Author(s):  
John P. Wourms ◽  
David Evans
Keyword(s):  
Reproductive Cycle ◽  
Egg Size ◽  
Gonad Index ◽  
Egg Mass ◽  
Base Line ◽  
Annual Reproductive Cycle ◽  
Intertidal Habitat ◽  
Spawning Period ◽  
Egg Number ◽  
Xiphister Atropurpureus

Semimonthly determinations of the gonad index made during the course of a year show that Xiphister atropurpureus has an annual reproductive cycle. The gonad index (ovary) increases during midwinter, attains a maximum value of 20 in late April–May, and declines to a base-line value of 0.5 from June to December. Spawning occurs during a 6-week period in late April–May. Spawning takes place in zone 4 of the intertidal habitat. Eggs deposited singly are fertilized and then shaped into a spherical mass by the parents. As egg envelopes harden, they adhere to one another to form a coherent mass. The egg mass is guarded by one or both parents. The annual reproductive cycle is considered to be a necessary consequence of the energetic demands of oogenesis combined with selection for a spawning period which is environmentally optimal. Alternative cycles based on modification of the present egg size (large)/egg number (few) relationship do not appear feasible, since the required modification of the egg size/egg number ratio would be selectively disadvantageous. The intertidal habitat of Xiphisier is subject to several potential environmental hazards: wave shock, reduced salinity due to rain and runoff, and excessively high or low temperatures. These are seasonal hazards which occur during winter or summer. Spawning is timed (April–May), so the probability that developing eggs will be exposed to environmental risks is minimized while the probability of exposure to environmental benefits is maximized. It is suggested that the reproductive cycle is under photoperiodic control.

Effects of Spined Soldier Bug (Hemiptera Pentatomidae) Augmentation and Sticky Barrier Bands on Gypsy Moth (Lepidoptera: Lymantriidae) Density in Oak Canopies2

1994 ◽  
Vol 29 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Kevin W. Thorpe ◽  
Ralph E. Webb ◽  
Jeffrey R. Aldrich ◽  
Kathy M. Tatman
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Larval Density ◽  
Podisus Maculiventris ◽  
Egg Masses ◽  
Oak Trees ◽  
Gypsy Moths ◽  
Spined Soldier Bug ◽  
Augmentative Releases

The effects of sticky barrier bands, augmentative releases of the spined soldier bug, Podisus maculiventris (Say), and the deployment of P. maculiventris pheromone on gypsy moth, Lymantria dispar (L.), larval density in the canopy of oak trees were tested. Sticky barrier bands used alone reduced larval gypsy moth density by ≈35%. The release of 5,810 P. maculiventris nymphs per tree or the deployment of P. maculiventris pheromone to trees on which sticky barrier bands had been applied had no additional effect on gypsy moth larval density. None of the treatments affected the number of gypsy moth egg masses produced. Significantly more P. maculiventris adults were observed on trees with the pheromone, but higher numbers of nymphs were not subsequently observed on these trees. Counts of gypsy moths beneath burlap bands prior to gypsy moth pupation were about four times higher on unbanded than on banded trees, but counts of pupae beneath burlap bands did not differ between treatments.

SPATIAL DISTRIBUTION OF ADULTS OFOOENCYRTUS KUVANAE(HYMENOPTERA: ENCYRTIDAE), AN EGG PARASITE OFLYMANTRIA DISPAR(LEPIDOPTERA: LYMANTRIIDAE)

1982 ◽  
Vol 114 (12) ◽  
pp. 1109-1120 ◽  
Author(s):  
M. W. Brown ◽  
E. Alan Cameron
Keyword(s):  
Spatial Distribution ◽  
Gypsy Moth ◽  
Tree Species ◽  
Small Sample ◽  
Egg Mass ◽  
Parasite Abundance ◽  
Egg Masses ◽  
Positive Correlation ◽  
Wide Range ◽  
Mass Volume

AbstractThe spatial distribution of adultOoencyrtus kuvanae(Howard) (Hymenoptera: Encyrtidae) was examined in central Pennsylvania during 1978–1980. Data were gathered over a wide range of gypsy moth (Lymantria dispar(L.) (Lepidoptera: Lymantriidae)) densities and from all phases of population growth. There was a linear relationship between the log variance and log mean, fitting Taylor's Power Law with a power of 1.27. The degree of aggregation inO. kuvanaepopulations, as measured by the variance-to-mean ratio, was correlated positively with the abundance of the parasite, and was independent of host density. Aggregation was believed to result from the habit of the female parasite ovipositing repeatedly on the same egg mass, and the resultant progeny emerging synchronously. Behavior and density ofO. kuvanaepopulations were found to depend upon the gypsy moth population condition, i.e., low, rising, high stable, outbreak, or collapsed. The frequency distribution ofO. kuvanaepopulations fit the Poisson at densities less than 0.2 parasite adult per egg mass, a condition which occurred early and late (July, November) in the season, and the negative binomial above this density; a few distributions fit the log normal. The data were also analyzed using analyses of variance (multivariate and univariate), correlation, and regression techniques. All main effects, i.e., study area, host egg mass volume, egg mass height from the ground (within the 0–2 m sampling universe), aspect of the egg mass on the tree, and tree species, were important in explaining the variance in parasite abundance; study area differences were the most important. The effects of aspect and tree species were explained on the basis of small sample sizes, and not studied further. There was a positive correlation between host egg mass volume (= size) and parasite abundance. There was also a positive correlation between the height of the egg mass and parasite abundance during the summer; however, this relationship became negative by late fall. This seasonal change in vertical distribution was attributed to the tendency ofO. kuvanaeto be closer to the ground where they overwinter. Variation in adult abundance was generally greater among gypsy moth egg masses on different trees than among egg masses on the same tree, except at low parasite densities. This was attributed to the parasites searching for egg masses on one tree before dispersing to another.

Influence of burlap-band colour on larval, pupal, and egg-mass counts of Lymantria dispar (Lepidoptera: Lymantriidae)

2003 ◽  
Vol 135 (6) ◽  
pp. 869-877
Author(s):  
David B. Roden
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Field Experiments ◽  
Quercus Rubra ◽  
Egg Mass ◽  
Egg Masses ◽  
Band Position ◽  
The Mean ◽  
Pupation Site ◽  
Selection Of

AbstractThis paper describes the effect of the colour of burlap bands (black versus naturally coloured or tan burlap) affixed to red oak, Quercus rubra (L.) (Fagaceae), and how it influences selection of larval resting site, pupation site, and egg-mass counts of gypsy moth, Lymantria dispar (L.). In field experiments with half black and half tan burlap bands, the mean number of larvae, pupae, and egg masses were significantly greater under the black section of burlap. Individual burlap bands composed of either black or tan burlap affixed to separate trees produced similar significant results for larvae and pupae. When two burlap bands composed of opposite colours (black versus tan) were affixed to the same tree, significantly more larvae were found under the upper band, regardless of colour. In contrast, pupa and egg-mass densities were significantly greater under black bands, regardless of band position.

scholarly journals NET GENETIC AND TEMPORARY EPISTATIC OR MATERNAL ENVIRONMENTAL RESPONSES TO SELECTION FOR EGG PRODUCTION IN CHICKENS

Genetics ◽  
1981 ◽  
Vol 99 (2) ◽  
pp. 309-321
Author(s):  
G L Bennett ◽  
G E Dickerson ◽  
R S Gowe ◽  
A J McAllister ◽  
J A B Emsley
Keyword(s):  
Egg Production ◽  
Transmitted Disease ◽  
Selection Response ◽  
Egg Mass ◽  
Mass Selection ◽  
Total Response ◽  
Egg Weight ◽  
Egg Masses ◽  
Egg Number ◽  
Maternal Responses

ABSTRACT The difference between progeny from selected and unselected parents (T) was experimentally partitioned into net genetic change (GA), temporary favorable epistatic combinations (GEP) and egg-transmitted maternal environment (M) in two strains of Leghorns selected over 14 years for early pure-strain egg production. Differences among progeny from selected sires and dams, selected sires only, selected dams only, unselected sires and dams and the parental generation were equated to expected GA, GEP and M responses for each trait. Total response was 3.3% for early egg number, 3.7% for total egg number, 0.5% for egg weight, 3.8% for early egg mass and 4.2% for total egg mass. Among progeny that survived the test period and were judged to be normal, total response was 2.6% for total number of eggs, 3.0% for early egg mass and 3.1% for total egg mass. The percentage of T attributed to GA was 9% for early egg number, 24% for total egg number, 43% for early egg mass and 47% for total egg mass; but 52% for total egg number, 98% for early egg mass and 71% for total egg mass of normal survivors. Temporary maternal selection responses (M) were (1) positive for number of eggs and egg masses, (2) greater for all progeny than for normal survivors, and (3) increased with progeny age. The results suggest that M was caused by reduced egg-transmitted disease. Epistatic selection response was positive for earlier sexual maturity and for number of eggs, but negative for egg weight and thus was small for egg masses. Temporary epistatic and maternal responses can explain overestimation of additive genetic response from offspring-parent regression or from replicated single-generation selection and apparent superiority of mass selection over family or combined selection.

Destruction of Gypsy Moth Egg Masses (Using Surfactants, Detergents, Oils or Conventional Insecticides) for Quarantine and Community Action Programs2

1994 ◽  
Vol 29 (3) ◽  
pp. 305-317
Author(s):  
R. E. Webb ◽  
W. H. McLane ◽  
J. A. Finney ◽  
L. Venables ◽  
G. B. White ◽  
...  
Keyword(s):  
Soybean Oil ◽  
Gypsy Moth ◽  
Agricultural Research ◽  
Community Action ◽  
Egg Mass ◽  
Mass Destruction ◽  
Egg Masses ◽  
Highly Active ◽  
Methods Development ◽  
Development Center

A series of studies were conducted, beginning in 1976, at the Otis Methods Development Center, Otis ANGB, MA, and beginning in 1982 at the Beltsville Agricultural Research Center, Beltsville, MD, to evaluate surfactants, detergents, oils, and insecticides as egg mass destruction agents for use in quarantine and community action programs. Surfactants, oils, and detergents tended to be more active when applied in the fall, while conventional insecticides were generally more active when applied in the spring. Some products, especially soybean oil, were highly active throughout the gypsy moth egg stage (July–March). A soybean-oil based product has been registered for this use. A 50% concentration of soybean oil is recommended for quarantine purposes, while a 25% concentration should be suitable for homeowners and arborists.

Effect of size on reproductive output of giant crabs Pseudocarcinus gigas (Lamarck): Oziidae

1997 ◽  
Vol 48 (7) ◽  
pp. 581 ◽  
Author(s):  
Caleb Gardner
Keyword(s):  
Egg Size ◽  
Carapace Length ◽  
Reproductive Output ◽  
Ovarian Development ◽  
Female Size ◽  
Allometric Model ◽  
Egg Masses ◽  
Eastern Australia ◽  
Egg Number ◽  
Western Victoria

Fecundity and egg size of giant crabs (Pseudocarcinus gigas) were determined from egg masses of 162 crabs sampled from three sites in south-eastern Australia: western Victoria, western Tasmania and eastern Tasmania. Crabs ranged in carapace length from 126 to 220 mm and egg number ranged from 830000 to 2500000. Egg number and egg size increased with size of female. There appeared to be a decline in number of eggs and size of eggs with successive broods produced between moults. Sampling locality appeared to have little effect on reproductive output. Regression of an allometric model of log egg number to log crab size had a slope of 1.76 which was significantly less than 3.0. This indicates there is not a simple volumetric relationship between the variables, which would tend to occur if increasing fecundity with female size was a simple function of increased body space available for ovarian development. This pattern appeared to be a function of decreasing egg number and size with successive broods, and the trend of increasing egg size with female size.

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