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

2002 ◽  
Vol 134 (2) ◽  
pp. 269-279 ◽  
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.

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

1996 ◽  
Vol 74 (5) ◽  
pp. 708-715 ◽  
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.

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

2001 ◽  
Vol 11 (5) ◽  
pp. 637-647 ◽  
Author(s):  
Ann E. Hajek ◽  
Micheal M. Wheeler ◽  
Callie C. Eastburn ◽  
Leah S. Bauer
Keyword(s):  
Gypsy Moth ◽  
Fungal Pathogen ◽  
Entomophaga Maimaiga ◽  
Resting Spores

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.

Further spread of the gypsy moth fungal pathogen, Entomophaga maimaiga, to the west and north in Central Europe

2020 ◽  
Author(s):  
Jaroslav Holuša ◽  
Milan Zúbrik ◽  
Karolina Resnerová ◽  
Hana Vanická ◽  
Jan Liška ◽  
...  
Keyword(s):  
Central Europe ◽  
Gypsy Moth ◽  
Fungal Pathogen ◽  
The West ◽  
Entomophaga Maimaiga

Isolation and characterization of Entomophaga maimaiga sp. nov., a fungal pathogen of gypsy moth, Lymantria dispar, from Japan

1988 ◽  
Vol 51 (3) ◽  
pp. 229-241 ◽  
Author(s):  
Richard S. Soper ◽  
Mitsuaki Shimazu ◽  
Richard A. Humber ◽  
Mark E. Ramos ◽  
Ann E. Hajek
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Fungal Pathogen ◽  
Isolation And Characterization ◽  
Entomophaga Maimaiga

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.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil

2019 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Qixing Zhou ◽  
David Feindel ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

AbstractClubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot has been challenging, due largely to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores g-1 soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C and being buried in the soil were better conditions for spore survival than were −20°C, 30°C and at the soil surface. Most of the spores kept on the soil surface were killed, suggesting the negative effect of light on spore viability. Additional experiments confirmed that ultraviolet (UV) light contributed a large negative effect on spore viability as lower pathogenicity and less DNA content were observed from the 2-and 3-hour UV light treated spores compared to the untreated control. Finally, this work demonstrated that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

scholarly journals Plasmodiophora brassicae in its environment-effects of temperature and light on resting spore survival in soil.

2021 ◽  
Author(s):  
Kher Zahr ◽  
Alian Sarkes ◽  
Yalong Yang ◽  
Hafiz Ahmed ◽  
Qixing Zhou ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Uv Light ◽  
Quantitative Polymerase Chain Reaction ◽  
Soil Surface ◽  
Spore Viability ◽  
Resting Spore ◽  
Infected Root ◽  
Resting Spores ◽  
Negative Effect ◽  
C 30

Clubroot caused by Plasmodiophora brassicae is an important disease on cruciferous crops worldwide. Management of clubroot is challenging, largely due to the millions of resting spores produced within an infected root that can survive dormant in the soil for many years. This study was conducted to investigate some of the environmental conditions that may affect the survival of resting spores in the soil. Soil samples containing clubroot resting spores (1 × 107 spores/g soil) were stored at various temperatures for two years. Additionally, other samples were buried in soil, or kept on the soil surface in the field. The content of P. brassicae DNA and the numbers of viable spores in the samples were assessed by quantitative polymerase chain reaction (qPCR) and pathogenicity bioassays, respectively. The results indicated that 4°C, 20°C, and being buried in the soil were more conductive conditions for spore survival compared to -20°C, 30°C, and at the soil surface. 99.99% of the spores kept on the soil surface were non-viable, suggesting a negative effect of light on spore viability. Additional experiments confirmed the negative effect of UV light on spore viability as spores receiving 2- and 3-hour UV light exhibited lower disease potential and contained less DNA content compared to the untreated control. Finally, this work confirmed that DNA-based quantification methods such as qPCR can be poor predictors of P. brassicae disease potential due to the presence and persistence of DNA from dead spores.

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