Introduction and Spread of the Fungal Pathogen Entomophaga maimaiga (Zygomycetes: Entomophthorales) Along the Leading Edge of Gypsy Moth (Lepidoptera: Lymantriidae) Spread

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.

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Storage of Resting Spores of the Gypsy Moth Fungal Pathogen, Entomophaga maimaiga

Biocontrol Science and Technology ◽

10.1080/09583150120076184 ◽

2001 ◽

Vol 11 (5) ◽

pp. 637-647 ◽

Cited By ~ 5

Author(s):

Ann E. Hajek ◽

Micheal M. Wheeler ◽

Callie C. Eastburn ◽

Leah S. Bauer

Keyword(s):

Gypsy Moth ◽

Fungal Pathogen ◽

Entomophaga Maimaiga ◽

Resting Spores

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Epizootic occurrence of Entomophaga maimaiga at the leading edge of an expanding population of the gypsy moth (Lepidoptera: Lymantriidae) in north-central Ontario

The Canadian Entomologist ◽

10.4039/n04-002 ◽

2004 ◽

Vol 136 (6) ◽

pp. 875-878 ◽

Cited By ~ 5

Author(s):

Yannick Villedieu ◽

Kees van Frankenhuyzen

Keyword(s):

New York ◽

Gypsy Moth ◽

New York State ◽

Forest Health ◽

Population Expansion ◽

Leading Edge ◽

North Shore ◽

The North ◽

Entomophaga Maimaiga ◽

Expanding Population

Ever since its entry from New York State in the late 1960s, the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), has continued to expand its distribution in Ontario to the north and west (Nealis and Erb 1993). Outbreaks were recorded for the first time in the Sudbury – North Bay region in the early 1990s, by which time there was evidence of resident populations extending along the north shore of Lake Huron as far west as Lake Superior. The population expansion along the north shore is characterized by a patchy occurrence of small outbreaks, which typically last for a few years and then disappear (Annual Forest Health Reports, Great Lakes Forestry Centre, http://www.glfc.cfs.nrcan.gc.ca/foresthealth/index_e.html). Nealis et al. (1999) found that winter weather, parasitoids, and the gypsy-moth-specific fungal pathogen Entomophaga maimaiga Humber, Shimazu et Soper (Zygomycetes: Entomophthorales) were the most prominent sources of mortality in those transient outbreaks.

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Short and Long Range Dispersal in the Gypsy moth (Lepidoptera: Lymantriidae) Fungal Pathogen,Entomophaga maimaiga(Zygomycetes: Entomophthorales)

Environmental Entomology ◽

10.1603/0046-225x-32.1.111 ◽

2003 ◽

Vol 32 (1) ◽

pp. 111-122 ◽

Cited By ~ 20

Author(s):

Ronald M. Weseloh

Keyword(s):

Long Range ◽

Gypsy Moth ◽

Fungal Pathogen ◽

Entomophaga Maimaiga

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Detecting the titer in forest soils of spores of the gypsy moth (Lepidoptera: Lymantriidae) fungal pathogen, Entomophaga maimaiga (Zygomycetes: Entomophthorales)

The Canadian Entomologist ◽

10.4039/ent134269-2 ◽

2002 ◽

Vol 134 (2) ◽

pp. 269-279 ◽

Cited By ~ 13

Author(s):

Ronald M. Weseloh ◽

Theodore G. Andreadis

Keyword(s):

Forest Soils ◽

Gypsy Moth ◽

Fungal Pathogen ◽

Spore Viability ◽

Resting Spore ◽

Entomophaga Maimaiga ◽

Resting Spores ◽

A Site ◽

Spore Load

AbstractBioassays and direct counts were used to assess the abundance of resting spores of the gypsy moth, Lymantria dispar (L.), fungal pathogen, Entomophaga maimaiga Humber, Shimazu and Soper in forest soils. Resting spores in soil collected in October, January, and March and held under refrigeration germinated as readily as spores collected in April, but those collected in April germinated faster. Bioassays of resting spores in soils from different sites in Connecticut were directly related to results obtained from physically counting spores in the soil, and weakly correlated with a previously developed forest-based bioassay. The number of resting spores in a site was inversely related to the number of years since the site had last been defoliated by the gypsy moth, resulting in an implied maximum viability of resting spores of about 10 years. This maximum longevity was similar to a direct measure of long-term resting-spore viability. The study implies that resting-spore load in the soil may be an important determinant of the ability of the pathogen to control the gypsy moth.

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Interactions between the introduced fungal pathogen Entomophaga maimaiga and indigenous tachinid parasitoids of gypsy moth Lymantria dispar in Bulgaria

Phytoparasitica ◽

10.1007/s12600-012-0269-6 ◽

2012 ◽

Vol 41 (2) ◽

pp. 125-131 ◽

Cited By ~ 5

Author(s):

Georgi Georgiev ◽

Zdravko Hubenov ◽

Margarita Georgieva ◽

Plamen Mirchev ◽

Maria Matova ◽

...

Keyword(s):

Gypsy Moth ◽

Lymantria Dispar ◽

Fungal Pathogen ◽

Entomophaga Maimaiga

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Assessing the climatic potential for epizootics of the gypsy moth fungal pathogen Entomophaga maimaiga in the North Central United States

Canadian Journal of Forest Research ◽

10.1139/x09-117 ◽

2009 ◽

Vol 39 (10) ◽

pp. 1958-1970 ◽

Cited By ~ 10

Author(s):

Nathan W. Siegert ◽

Deborah G. McCullough ◽

Robert C. Venette ◽

Ann E. Hajek ◽

Jeffrey A. Andresen

Keyword(s):

United States ◽

Gypsy Moth ◽

Fungal Pathogen ◽

Weather Conditions ◽

Eastern United States ◽

Spring Temperature ◽

North Central ◽

The North ◽

Temperature And Precipitation ◽

Entomophaga Maimaiga

The fungal pathogen Entomophaga maimaiga Humber, Shimazu et Soper has become an important biocontrol for gypsy moth ( Lymantria dispar (L.)) in the northeastern United States and is commonly introduced into new areas with established gypsy moth populations. Germination of the fungus is dependent on spring temperature and moisture, but specific conditions associated with epizootics have not been determined. Whether E. maimaiga will be as effective in other regions that experience different weather conditions is not yet known. We examined similarity of weather conditions associated with 16 documented E. maimaiga epizootics with conditions at 1351 North American locations using the climate-matching software CLIMEX. Based on CLIMEX’s overall index of climatic similarity, long-term annual climatic patterns across much of the eastern United States were 60%–80% similar to the conditions associated with epizootics. Monthly weather records from 1971 to 2000 in nine North Central states were examined to compare precipitation and temperature with conditions observed during epizootics. Based on climatic averages identified with the documented epizootics, temperature and precipitation conditions in Illinois, Indiana, Iowa, Kentucky, Missouri, and Ohio were more conducive for epizootics than conditions in Minnesota, Wisconsin, and Michigan, which were likely to support E. maimaiga epizootics in fewer than 6 of the 30 years considered.

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Types of spores produced by Entomophaga maimaiga infecting the gypsy moth Lymantria dispar

Canadian Journal of Botany ◽

10.1139/b96-089 ◽

1996 ◽

Vol 74 (5) ◽

pp. 708-715 ◽

Cited By ~ 35

Author(s):

Ann E. Hajek ◽

Mitsuaki Shimazu

Keyword(s):

Gypsy Moth ◽

Lymantria Dispar ◽

Fungal Pathogen ◽

Fungal Spores ◽

Serial Passage ◽

Molting Cycle ◽

Resting Spore ◽

Entomophaga Maimaiga ◽

Resting Spores ◽

Study Support

We investigated the association of environmental factors (temperature, photoperiod, host molting status) and fungal factors (isolate, dose, strain attenuation) with the production of conidia versus resting spores by the entomopathogenic fungus Entomophaga maimaiga infecting the larvae of the gypsy moth Lymantria dispar. Fungal spores produced from individual cadavers of larvae killed by E. maimaiga can include conidia discharged from the cadaver surface, resting spores (azygospores) within the cadaver, or both spore types. The single factor having the greatest impact on the type of spore produced was host age; second instars virtually never contained resting spores, independent of temperature, while fifth instar cadavers contained resting spores more frequently at higher temperatures. However, there was increased conidiation at lower temperatures. Photoperiod was the only factor studied that did not significantly influence the type of spore produced. Resting spore production was negatively associated with the molting cycle; cadavers of those larvae that molted or exhibited premolt characteristics during the period between infection and death contained fewer resting spores. Increased fungal dose yielded more resting spores, as did extensive serial passage, which simultaneously caused a decrease in conidiation. Fungal isolates varied in the types of spores produced, with fewer cadavers of larvae killed by the least virulent isolate discharging conidia. Results from this study support the hypothesis that both the condition of the fungal pathogen as well as the environment surrounding it contribute to the types of spores produced. Keywords: fungal sporulation, resting spores, azygospores, Entomophthorales, Entomophaga maimaiga, biological control.

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