Comparison of Aerially-Applied Gypchek Strains Against Gypsy Moth (Lepidoptera: Lymantriidae) in the Presence of an Entomophaga maimaiga Epizootic

2005 ◽  
Vol 40 (4) ◽  
pp. 446-460 ◽  
Author(s):  
R. E. Webb ◽  
G. B. White ◽  
J. D. Podgwaite ◽  
V. D'Amico ◽  
J. Slavicek ◽  
...  
Keyword(s):  
Gypsy Moth ◽  
Larval Mortality ◽  
Larval Population ◽  
Usda Forest Service ◽  
Entomophaga Maimaiga ◽  
Wave Effects ◽  
Late Instar ◽  
Fungal Entomopathogen ◽  
Occlusion Bodies ◽  
Second Wave

The standard strain (LDP-226) of Gypchek®, a nucleopolyhedrovirus product registered by the USDA Forest Service against the gypsy moth, Lymantria dispar (L.), was compared against a strain, LdMNPV-203NL (NL = nonliquefying), that was developed for production in cell culture. Both strains were applied by air to U.S. government property in Prince Georges Co., MD, in early May 2003 at the rate of 1 × 1012 occlusion bodies per ha. The two goals of the study were (1) to compare the first and second wave effects of the two strains against gypsy moth populations; and (2) to delineate the combined effects of the applied virus and the expected epizootic of the gypsy moth specialist fungal entomopathogen Entomophaga maimaiga Humber, Shimazu, and Soper. Heavy rainfall in May and June preceded a massive epizootic of E. maimaiga, whose effects did not mask the first wave of viral mortality. When the effect of application sequence was considered, it was concluded that the two strains were equivalent in their first-wave impacts. High fungal-induced mid and late-season gypsy moth larval mortality suppressed the second wave of virus at all evaluation sites. There were no obvious differences in the second waves engendered by the two LdNPV strains in the greatly reduced late-instar larval population.

Quantitative Analysis of a Pathogen-Induced Premature Collapse of a “Leading Edge” Gypsy Moth (Lepidoptera: Lymantriidae) Population in Virginia

1999 ◽  
Vol 34 (1) ◽  
pp. 84-100 ◽  
Author(s):  
R. E. Webb ◽  
G. B. White ◽  
K. W. Thorpe ◽  
S. E. Talley
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Nuclear Polyhedrosis Virus ◽  
Leading Edge ◽  
Late Season ◽  
Early Appearance ◽  
Entomophaga Maimaiga ◽  
Resting Spores ◽  
Nuclear Polyhedrosis ◽  
Second Wave

The population dynamics of a “leading edge” (= at the edge of the expanding gypsy moth invasion) gypsy moth, Lymantria dispar (L.), population was monitored for 3 years (1995–97), with emphasis on the interactions of the gypsy moth nuclear polyhedrosis virus (LdNPV) and the fungus Entomophaga maimaiga Humber, Shimazu, & Soper. Gypsy moth populations in the woodlots varied from very sparse to high (potentially defoliating) levels. LdNPV was strongly density dependent, being confirmed only from the higher populated woodlots. In contrast, the fungus was similarly active in both sparse and highly-populated woodlots. In 1995, the fungal epizootic developed late in the season, with most larvae succumbing during stadia 5–6 and producing mainly resting spores (azygospores). Estimated mortality due to fungus averaged 68% in high-density plots and 85% in low-density plots. LdNPV mortality occurred in a two-wave epizootic, although second-wave LdNPV mortality was undoubtedly reduced because of the reduction of late-season larvae due to fungus activity. Estimated mortality due to LdNPV averaged 14% in highly-populated plots and 1% in low-population plots. In 1996, high levels of fungal-induced mortality occurred earlier in the gypsy moth season than in the previous year. Most gypsy moth larvae in 1996 died in a mid-season wave of fungal-induced mortality, with necropsied cadavers containing only conidia. This resulted in relatively few larvae surviving to late instars. At this time, a second wave of fungus-induced mortality occurred, with over half of the necropsied cadavers containing resting spores. The depletion of the gypsy moth populations by the fungus in 1995 resulted in a greatly reduced first wave of LdNPV in all plots in 1996, and perhaps due to the early appearance of the fungus in 1996, LdNPV was nearly absent from late-season larvae collected from all plots. In 1997, gypsy moth populations were uniformly low, and no dead larvae were found in any of the plots.

DIFFERENCES IN THE UTILIZATION OF TREE SPECIES AS LARVAL HOSTS AND PUPATION SITES BY THE GYPSY MOTH, LYMANTRIA DISPAR (LEPIDOPTERA: LYMANTRIIDAE)

1984 ◽  
Vol 116 (5) ◽  
pp. 685-690 ◽  
Author(s):  
Yves Mauffette ◽  
Martin J. Lechowicz
Keyword(s):  
Gypsy Moth ◽  
Host Species ◽  
Quercus Rubra ◽  
Larval Mortality ◽  
Coniferous Species ◽  
Juglans Cinerea ◽  
Ostrya Virginiana ◽  
Carya Ovata ◽  
Host Trees ◽  
Late Instar

AbstractIn the summer of 1980, gypsy moth populations were monitored in 13 sparsely infested forests in southwestern Quebec; counts of living and dead larvae and pupae were made on 1,870 trees representing 28 deciduous and one coniferous species. Contrary to our null expectations, the proportionate numbers of pupae compared with larvae on the various host species were not equal. Hosts more preferred by larvae were less preferred by pupae, and vice versa. For example, pupae were disproportionately abundant on host species like Acer pensylvanicum L., Carya ovata (Mill.) K. Koch, and Juglans cinerea L. which are not generally favored larval hosts. Conversely, favored larval hosts like Quercus rubra L. and Ostrya virginiana (Mill.) K. Koch carried lower numbers of pupae than expected from the numbers of larvae feeding on them. Such differential utilization of host trees by larvae versus pupae, which can arise either from host-dependent differences in larval mortality or from late instar migration between hosts, may contribute to maintaining the broad polyphagy of gypsy moth larvae.

Relating Aerial Deposition of Entomophaga maimaiga Conidia (Zoopagomycota: Entomophthorales) to Mortality of Gypsy Moth (Lepidoptera: Erebidae) Larvae and Nearby Defoliation

2019 ◽  
Vol 48 (5) ◽  
pp. 1214-1222 ◽  
Author(s):  
Joseph S Elkinton ◽  
Tonya D Bittner ◽  
Valerie J Pasquarella ◽  
George H Boettner ◽  
Andrew M Liebhold ◽  
...  
Keyword(s):  
New England ◽  
Gypsy Moth ◽  
Landsat Imagery ◽  
The United States ◽  
Viral Pathogen ◽  
Entomophaga Maimaiga ◽  
Gypsy Moths ◽  
Airborne Conidia ◽  
Late Instar ◽  
Highly Correlated

Abstract We collected data on mortality of late-instar gypsy moth, Lymantria dispar (L.), from outbreak populations over 4 wk in June 2017 at 10 sites in the New England region of the United States, along with estimated rainfall at these sites. Deposition of airborne conidia of the fungal pathogen, Entomophaga maimaiga Humber, Shimazu & R.S. Soper, was measured at these same sites as well as at seven other locations in New England. We also quantified the geographical distribution of gypsy moth-caused defoliation in New England in 2017 and 2018 from Landsat imagery. Weekly mortality of gypsy moth larvae caused by E. maimaiga correlated with local deposition of conidia from the previous week, but not with rainfall. Mortality from this pathogen reached a peak during the last 2 wk of gypsy moth larval development and always exceeded that caused by LdNPV, the viral pathogen of gypsy moth that has long been associated with gypsy moth outbreaks, especially prior to 1989. Cotesia melanoscela (Ratzeburg) was by far the most abundant parasitoid recovered and caused an average of 12.6% cumulative parasitism, but varied widely among sites. Deposition of E. maimaiga conidia was highly correlated with percent land area defoliated by gypsy moths within distances of 1 and 2 km but was not significantly correlated with defoliation at distances greater than 2 km. This is the first study to relate deposition of airborne conidia of E. maimaiga to mortality of gypsy moths from that agent.

Formation and germination of Entomophaga maimaiga azygospores

1997 ◽  
Vol 75 (10) ◽  
pp. 1739-1747 ◽  
Author(s):  
Ann E. Hajek ◽  
Richard A. Humber
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Early Summer ◽  
Resting Spore ◽  
Body Development ◽  
Entomophaga Maimaiga ◽  
Resting Spores ◽  
Late Instar ◽  
Hyphal Bodies ◽  
Hyphal Body

Azygospores (resting spores) of the gypsy moth fungal pathogen Entomophaga maimaiga are produced in abundance during late spring and early summer in late-instar gypsy moth larvae (Lymantria dispar). Azygospores subsequently form, each from an individual hyphal body. Development of azygospores occurs asynchronously over several days; by 5 days after host death, greater than 60% of fungal cells had matured from hyphal bodies to the final double-walled resting state. Azygospores undergo constitutive dormancy and, under field conditions, will not germinate for approximately 9 months after production. Azygospores do not require nutrients to germinate. Germination of field-collected resting spores under laboratory conditions began more than 2 days after transfer from the field to the laboratory. Higher levels of germination occurred with a 14 h L: 10 h D cycle compared with 13 h L: 11 h D or 12 h L: 12 h D. Azygospores germinate relatively slowly and germination rates were greatest between 4 and 8 days, with a total of 71.8 or 72.5% germination by 16 days at 14 h L: 10 h D and 15 or 20 °C, respectively. During 1994 and 1995, resting spores began causing infections in experimental larvae in early May, about 1 – 2 weeks prior to gypsy moth egg hatch, and ceased causing infections in mid to late June, when late instars were present. This latter timing is a correction of previously reported information. Bioassays investigating resting spore activity determined that during 1994, once resting spores began germinating in the field, levels of infection were positively associated with soil moisture. Key words: azygospores, resting spores, entomopathogenic fungi, Entomophaga maimaiga, Lymantria dispar, biological control.

Expression of Entomophaga maimaiga at Several Gypsy Moth (Lepidoptera: Lymantriidae) Population Densities and the Effect of Supplemental Watering

2004 ◽  
Vol 39 (2) ◽  
pp. 223-234 ◽  
Author(s):  
Ralph E. Webb ◽  
Mary Willeford Bair ◽  
Geoffrey B. White ◽  
Kevin W. Thorpe
Keyword(s):  
Gypsy Moth ◽  
Larval Mortality ◽  
High Density ◽  
Mortality Factor ◽  
Egg Mass ◽  
Low Density ◽  
Mortality Factors ◽  
Natural Rainfall ◽  
Resting Spore ◽  
Entomophaga Maimaiga

Assessment of gypsy moth, Lymantria dispar L. (Lepidoptera: Lymantriidae), populations in western Virginia during the year 2000, showed that larval mortality factors differed as a function of population density. Larval mortality, primarily due to the gypsy moth-specific entomopathogenic fungus Entomophaga maimaiga Humber, Shimazu and Soper, was 28.7% in high-density plots (averaging 476.8 larvae per 5 burlap bands) but only 16.5% in low-density plots (averaging 60.8 larvae per 5 burlap bands). On the contrary, “missing” was the dominant mortality factor in low-density plots (6.5% in high-density plots vs 65.6% in low-density plots). This study was designed to assess the potential for inducing an earlier epizootic by facilitating the early germination of resident resting spores by spraying water around the base of trees. Eight of the high-density plots with measured natural E. maimaiga resting-spore loads were selected for a supplemental watering study conducted in 2001. Four plots received weekly watering to supplement natural rainfall, and four received only natural rainfall (control plots). More E. maimaiga occurred in watered plots than in control plots; however, treatment effects for watering were not significant. For a 01 June collection, fungal levels were 17% (ground) and 12% (canopy) for the watered plots vs 12% (ground) and 10% (canopy) for control plots. For a 15 June collection, fungal levels were 74% (ground) and 29% (canopy) for the watered plots vs 60% (ground) and 14% (canopy) from control plots. Height effects were significant for the second date. Egg mass populations in watered plots declined significantly (78%) compared with control plots (4%) (P = 0.0433), possibly reflecting further mortality occurring after the second collection.

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.

Nucleopolyhedrovirus infection in obliquebanded leafroller (Lepidoptera: Tortricidae)

2002 ◽  
Vol 134 (3) ◽  
pp. 303-309 ◽  
Author(s):  
I. Pronier ◽  
J. Paré ◽  
J-C Wissocq ◽  
C. Vincent
Keyword(s):  
Fat Body ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Control Group ◽  
Choristoneura Rosaceana ◽  
Obliquebanded Leafroller ◽  
Naturally Occurring ◽  
The Family ◽  
Microscopic Studies ◽  
Occlusion Bodies

AbstractA virus isolated from obliquebanded leafroller, Choristoneura rosaceana (Harris), larvae collected in an apple, Malus domestica Borkh. (Rosaceae), orchard of Saint-Joseph-du-Lac (Quebec, Canada) was studied. Microscopic studies revealed that it was a uninucleocapsid nucleopolyhedrovirus from the family Baculoviridae. Larval mortality was approximately 75% (0% mortality in control group) in larvae infected as third instars immersed in a suspension of 1.7 × 108 occlusion bodies/mL. The average time for larval mortality was 23 ± 3 d after treatment. The majority (95.5%) of infected larvae died as fifth or sixth instars. Infection was observed primarily in fat body cells, and occasionally in the tracheal matrix and epidermis. Mean larval development time of infected larvae surviving to pupae was 20 ± 3 d, significantly greater than the 18 ± 3 d observed in control larvae. Adult emergence was significantly lower in pupae of treated larvae (73.6%) than in the control group (93.5%). Our work constitutes the first baseline study of naturally occurring virus of the obliquebanded leafroller.

PERSISTENCE AND DISPERSAL OF THE NUCLEAR POLYHEDROSIS VIRUS OF NEODIPRION SERTIFER (GEOFFROY) (HYMENOPTERA: DIPRIONIDAE) IN A VIRUS-FREE LODGEPOLE PINE PLANTATION IN SWEDEN

1988 ◽  
Vol 120 (10) ◽  
pp. 887-892 ◽  
Author(s):  
Einar Olofsson
Keyword(s):  
Nuclear Polyhedrosis Virus ◽  
Lodgepole Pine ◽  
Larval Mortality ◽  
Neodiprion Sertifer ◽  
Experimental Plot ◽  
Pine Plantation ◽  
Larval Population ◽  
Polyhedrosis Virus ◽  
Nuclear Polyhedrosis ◽  
High Level

AbstractAn outbreak of Neodiprion sertifer (Geoffroy) was studied in a lodgepole pine plantation. It was the first tree generation on a 60-ha peatland area. The nuclear polyhedrosis virus (NPV) of N. sertifer was not found in the larval population or in the soil. Within a 1.7-ha experimental plot, a 0.35-ha block was treated with NPV and the ensuing epizootic was studied during three successive summers. The treatment caused 50% mortality of fourth- and fifth-instar larvae. The NPV persisted in the treated block and gradually dispersed into the adjacent blocks. After 2 years, larval mortality was 78% in the treated block and 21% at a distance of 110–125 m from it. The larval population remained at a high level and the outbreak expanded from the experimental plot to the entire 60-ha area in the years following the virus treatment, but few virus-diseased colonies were observed outside the experimental plot. Thus, the capability of this NPV to persist and spread was not sufficient to control and contain the sawfly outbreak.

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