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Ann E. Hajek - One of the best experts on this subject based on the ideXlab platform.
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survival and differential development of Entomophaga maimaiga and Entomophaga Aulicae zygomycetes entomophthorales in lymantria dispar hemolymph
Journal of Invertebrate Pathology, 2001Co-Authors: Claudia Lopez C Lastra, Donna M Gibson, Ann E. HajekAbstract:The closely related entomophthoralean fungi Entomophaga Aulicae and E. maimaiga are both host-specific pathogens of lepidopteran larvae. However, these fungi do not have the same host range. The first objective of this study was to compare the fate of E. Aulicae in the nonpermissive host Lymantria dispar with the fate of the successful pathogen E. maimaiga over the same time period. In the hemolymph of L. dispar injected with E. maimaiga protoplasts, the number of hemocytes demonstrated a decreasing trend after the first day postinjection and hemocytes completely disappeared by day 5, with the majority of larvae dying in 5.6 ± 0.1 days. In L. dispar larvae, E. maimaiga infections developed successfully, evidenced by increasing numbers of protoplasts and hyphal bodies prior to host mortality. In contrast, at day 5 hemocytes were readily visible in hemolymph of E. Aulicae-injected larvae, but E. Aulicae cells did not increase in numbers, although persisting in the hemolymph for at least 16 days postinjection. For both fungal species, when hemolymph samples from injected insects were introduced to culture media viable fungal cultures were always produced. Both E. Aulicae and E. maimaiga occurred in hemolymph initially after injection as protoplasts. For E. maimaiga, after day 3, <50% of fungal cells were hyphal bodies until insect death when most cells regenerated cell walls. For E. Aulicae, from day 2 equal numbers of fungal cells in the hemolymph occurred as protoplasts and hyphal bodies. To investigate the cause of fungistasis in E. Aulicae-injected larvae, E. Aulicae cell cultures exposed to partially purified protein fractions from hemolymph of larvae infected with either fungus displayed increased lysis and decreased viability at lower concentrations of protein fractions compared with E. maimaiga cell cultures. These studies demonstrate that E. Aulicae does not increase in L. dispar hemolymph, although it persists and results suggest that proteinaceous factors induced within the hemolymph may limit the capacity of E. Aulicae to develop successful infections.
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Pathology and Epizootiology of Entomophaga maimaiga Infections in Forest Lepidoptera
Microbiology and molecular biology reviews : MMBR, 1999Co-Authors: Ann E. HajekAbstract:The insect-pathogenic fungal pathogen Entomophaga maimaiga is endemic to northeastern Asia and was first found in North America in 1989. Due to repeated epizootics and spread within populations of the major forest defoliator in northeastern North America, the gypsy moth (Lymantria dispar), this pathogen has gained much notoriety. Although this pathogen was purposely introduced to North America for biological control of L. dispar in 1910 to 1911, it is questionable whether it became established at the time of release and then remained at innocuous levels until relatively recently. Alternatively, the fungal strain present in North America today could be a more recent accidental introduction. DNA analysis demonstrates that this pathogen differs significantly from North American members of the same species complex (the Lepidoptera-specific Entomophaga Aulicae species complex), and, to date, isolates of this introduced pathogen display little heterogeneity in North America. Nonsusceptible lepidopteran larvae have been identified, and either E. maimaiga is unable to penetrate the cuticle or the fungus cannot survive within the hemocoel. In the latter case, although E. maimaiga grows as protoplasts lacking cell walls in the host hemolymph, glycoproteins on plasma membranes of the protoplasts could lead to host recognition. Epizootiological studies demonstrate a clear association between fungal activity and environmental moisture but little association with host density under hypothesized conditions of high fungal density. Prediction of the occurrence of epizootics is not yet possible. E. maimaiga is easily established in new areas by releasing azygospores, but the ability to use this pathogen further for biological control will depend, in large part, on the development of mass production systems.
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A disjunct Californian strain of Entomophaga Aulicae infecting Orgyia vetusta.
Journal of invertebrate pathology, 1996Co-Authors: Ann E. Hajek, Donald R Strong, Scott Walsh, Julie C. SilverAbstract:Fungal epizootics occurred in abundant Orgyia vetusta (western tussock moth; Lepidoptera: Lymantriidae) populations on Lupinus arboreus bushes growing on the Pacific coast north of San Francisco, California. The causative pathogen was isolated and identified as Entomophaga Aulicae, Group II, based on RFLPs using rDNA and PCR-amplified rDNA products. Inability of this fungus to infect the lymantriid Lymantria dispar (gypsy moth) confirmed its distinction from Entomophaga maimaiga, the only other member of this species complex which predominantly infects lymantriids. Later instar wandering by O. vetusta in outbreak populations and close proximity of larvae in dense populations are characteristics most probably promoting development of E. Aulicae epizootics; these life history patterns are also typical of Lymantria dispar populations experiencing epizootics of E. maimaiga.
Richard A. Nolan - One of the best experts on this subject based on the ideXlab platform.
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effects of relative humidity and temperature on Entomophaga Aulicae conidium discharge from infected eastern hemlock looper larvae and subsequent conidium development
Journal of Invertebrate Pathology, 1995Co-Authors: Dawn M Mcdonald, Richard A. NolanAbstract:Abstract The effects of relative humidity (RH) and temperature on conidium discharge from Entomophaga Aulicae-infected eastern hemlock looper (Lambdina fiscellaria fiscellaria) larvae and subsequent conidium development were examined. Fourth-instar larvae were injected with 460 fungal protoplasts (=LC50 dosage). At 20°C, RH (66, 86, and 93%) had no effect on the level of larval mortality. At 93% RH, more primary, secondary, tertiary, quaternary, and quinary conidia were produced over a 2-day period than at either 66 or 86% RH. At 66% RH, only primary conidia were produced and only on 1 day. At 20°C, the highest level of germ tube formation by primary conidia occurred at 86% RH, whereas the highest level of secondary conidium production and the longest germ tubes occurred at 93% RH. Sixty-six percent RH was unsuitable for either germ tube or secondary conidium production. Injected larvae were initially incubated at 4, 10, 15, 20, 25, and 30°C. The highest level of larval mortality occurred at 20°C (93% RH). The time to host death decreased with increasing temperature. The number of degree-days to host death at 93% RH was 75 to 90 at 15°C, 80 to 100 at 20°C, and 75 to 100 at 25°C. At 20°C and 93% RH, the fungus produced an average of 1.2 × 105 primary conidia per fourth-instar larva.
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Physiological studies with the fungus Entomophaga Aulicae during morphogenesis in three different media under fermentation conditions
Canadian Journal of Microbiology, 1993Co-Authors: Richard A. NolanAbstract:The effects of three different media on amino acid uptake and production and glucose and oxygen utilization during protoplast growth and hyphal body production by the fungus Entomophaga Aulicae under fermentation conditions were studied. The three media consisted of a basal medium plus either (i) 2.8% fetal calf serum, (ii) 0.8% tryptic soy broth plus 0.4% bovine serum albumin, or (iii) 0.8% tryptic soy broth plus 0.4% calcium caseinate. The protoplasts grew most rapidly (initial peaks on days 2 and 3) and hyphal bodies were detected first (day 3) in the media containing albumin and caseinate. The day 9 hyphal body yields were 3.1 × 107, 7.5 × 108, and 3.1 × 109/10 L in media containing the serum, albumin, and caseinate, respectively. Growth in the albumin and caseinate media also gave the first detectable glucose utilization (days 2 and 3, respectively) and this rapidly increased to 94.9 and 90.6% utilization, respectively, on day 4. Oxygen and glucose utilization were closely related. During protoplast ...
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An inexpensive medium for mass fermentation production of Entomophaga Aulicae hyphal bodies competent to form conidia
Canadian Journal of Microbiology, 1993Co-Authors: Richard A. NolanAbstract:A mass fermentation medium for growth and morphogenesis of the entomopathogenic fungus Entomophaga Aulicae was developed. This fungus is a major pathogen of larval eastern hemlock looper and spruce budworm. The medium consists of a basal medium plus 0.8% tryptic soy broth and 0.4% calcium caseinate. This medium is a major breakthrough in that (i) the E. Aulicae developmental sequence from protoplast inoculum to hyphal bodies competent to form conidia can be carried out in a single medium without adjustment, (ii) by examining the fermentation product it can be determined if conidia can be produced prior to engaging in costly field spraying, (iii) this medium supports the growth of E. Aulicae isolates from different geographical areas, (iv) the medium is relatively inexpensive, (v) the hyphal bodies are easily separated from the spent growth medium, and (vi) the hyphal body yield is high.Key words: Entomophaga Aulicae, mass fermentation medium, hyphal bodies, conidia, insect biocontrol.
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Influence of a negatively charged surface (Teflon disk) on Entomophaga Aulicae protoplast morphogenesis under mass fermentation conditions
Canadian Journal of Botany, 1991Co-Authors: Richard A. NolanAbstract:The effects of a negatively charged surface (Teflon disk) on protoplast morphogenesis for the fungus Entomophaga Aulicae under mass fermentation conditions were determined. The control consisted of a vessel lacking such a disk. In the presence of the disk the initial three and sequentially produced protoplast stages (spindle shaped, early fusion sphere, and late fusion sphere protoplasts) recycled with the early fusion sphere predominating. The production of the subsequent and walled stage (i.e., hyphal body) was suppressed. The results are in contrast with those obtained in a previous study using a neutral (Mylar) and a positively charged (polypropylene) disk in which hyphal body production was enhanced. This technique provides a new and subtle approach for altering protoplast developmental patterns which avoids the use of mutagens or added chemical metabolic inhibitors. Key words: Entomophaga Aulicae, fungal protoplast morphogenesis, negatively charged surface, mass fermentation.
Julie C. Silver - One of the best experts on this subject based on the ideXlab platform.
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host range of the gypsy moth lepidoptera lymantriidae pathogen Entomophaga maimaiga zygomycetes entomophthorales in the field versus laboratory
Environmental Entomology, 1996Co-Authors: Linda Butler, Julie C. Silver, Scott Walsh, Fred P Hain, Felton L Hastings, Thomas M Odell, David R. SmitleyAbstract:Lepidopteran larvae were sampled in the field to determine levels of infection by the gypsy moth, Lymantria dispar (L.), fungal pathogen, Entomophaga maimaiga Humber, Shimazu & Soper. Lepidopteran larvae were reared from 7 plots in Virginia in which moderate density gypsy moth populations simultaneously exhibited from 40.8 to 97.5% E. maimaiga infection. From a total of 1,511 larvae from 52 species belonging to 7 lepidopteran families in 4 superfamilies, only 2 individuals, 1 of 318 forest tent caterpillars, Malacosoma disstria Hiibner (0.3% infection), and 1 of 96 Catocala ilia (Cramer) (1.0% infection), became infected by entomophthoralean pathogens. Results from genomic DNA probes and bioassays confirmed that E. maimaiga had caused these infections. Laboratory studies yielded infection over a greater diversity of species, and percentages of infection from laboratory studies were higher than findings from the field for the 1 species infected in both the laboratory and field. At all sites, the gypsy moth nuclear polyhedrosis virus also was found, occasionally causing epizootics, but viral occlusion bodies were never found in nontarget Lepidoptera that died. In addition, 279 nontarget Lepidoptera belonging to 34 species in 8 families were collected and reared from areas with low density native gypsy moth populations, and E. maimaiga infections were not found in these nontarget hosts, although E. maimaiga was active in gypsy moth populations. A survey of lepidopteran cadavers collected from 1989 to 1995 containing entomophthoralean spores documented E. maimaiga infections in 3 species of lymantriids. The Lepidoptera-specific North American endemic entomopathogen Entomophaga Aulicae (Reichardt in Bail) Humber, which is morphologically identical to E. maimaiga, was found in 1 geometrid species, 1 notodontid, 2 species of arctiids, and 1 introduced lymantriid, but in none of the gypsy moth larvae tested. Our results demonstrate that data from laboratory bioassays are poor estimates for predicting nontarget impact.
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A disjunct Californian strain of Entomophaga Aulicae infecting Orgyia vetusta.
Journal of invertebrate pathology, 1996Co-Authors: Ann E. Hajek, Donald R Strong, Scott Walsh, Julie C. SilverAbstract:Fungal epizootics occurred in abundant Orgyia vetusta (western tussock moth; Lepidoptera: Lymantriidae) populations on Lupinus arboreus bushes growing on the Pacific coast north of San Francisco, California. The causative pathogen was isolated and identified as Entomophaga Aulicae, Group II, based on RFLPs using rDNA and PCR-amplified rDNA products. Inability of this fungus to infect the lymantriid Lymantria dispar (gypsy moth) confirmed its distinction from Entomophaga maimaiga, the only other member of this species complex which predominantly infects lymantriids. Later instar wandering by O. vetusta in outbreak populations and close proximity of larvae in dense populations are characteristics most probably promoting development of E. Aulicae epizootics; these life history patterns are also typical of Lymantria dispar populations experiencing epizootics of E. maimaiga.
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Pathotypes in the Entomophaga grylli species complex of grasshopper pathogens differentiated with random amplification of polymorphic DNA and cloned-DNA probes.
Applied and environmental microbiology, 1995Co-Authors: Michael J. Bidochka, Julie C. Silver, Mark E. Ramos, Scott R. A. Walsh, Raymond J. St. Leger, Donald W. RobertsAbstract:The zygomycetous fungus Entomophaga grylli is a pathogen that shows host-specific variance to grasshopper subfamilies. Three pathotypes of the E. grylli species complex were differentiated by three molecular techniques. In the first method, the three pathotypes showed different fragment patterns generated by random amplification of polymorphic DNA (RAPD). There was little or no interisolate variability in RAPD fragment patterns within each pathotype. Passage of an isolate of pathotype 3, originally from an Australian grasshopper (Praxibulus sp.), through a North America grasshopper resulted in no differences in the resultant RAPD fragment patterns. In the second method, polymorphic RAPD fragments were used to probe the genomic DNA from the three pathotypes, and pathotype-specific fragments were found. In the third method, restriction fragments from genomic DNA of the three pathotypes were cloned and screened for pathotype specificity. A genomic probe specific for each pathotype was isolated. These probes did not hybridize to DNA from Entomophaga Aulicae or from grasshoppers. To facilitate the use of RAPD analysis and other molecular tools to identify pathotypes, a method for extracting DNA from resting spores from infected grasshoppers was developed. The DNA from the fractured resting spores was of sufficient integrity to be blotted and probed with the pathotype-specific DNA probes, thus validating the use of these probes for pathotype identification in field-collected grasshoppers.
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Sympatric occurrence of two Entomophaga Aulicae (Zygomycetes : Entomophthorales) complex species attacking forest lepidoptera
Journal of Invertebrate Pathology, 1991Co-Authors: Richard A. Humber, Scott Walsh, Julie C. SilverAbstract:Abstract Entomophthoralean fungi caused infections in sympatric larval populations of Lymantria dispar and Heterocampa guttivitta in New York and Vermont during 1989 and 1990. Gross morphology as well as restriction fragment length polymorphism and allozyme analyses determined that the Japanese fungus Entomophaga maimaiga was responsible for L. dispar mortality, while a different and otherwise unidentified member of the E. Aulicae species complex was responsible for H. guttivitta mortality. Bioassays confirmed that the fungus infecting H. guttivitta was not E. maimaiga; the fungal isolate from H. guttivitta could not infect L. dispar larvae.
Scott Walsh - One of the best experts on this subject based on the ideXlab platform.
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host range of the gypsy moth lepidoptera lymantriidae pathogen Entomophaga maimaiga zygomycetes entomophthorales in the field versus laboratory
Environmental Entomology, 1996Co-Authors: Linda Butler, Julie C. Silver, Scott Walsh, Fred P Hain, Felton L Hastings, Thomas M Odell, David R. SmitleyAbstract:Lepidopteran larvae were sampled in the field to determine levels of infection by the gypsy moth, Lymantria dispar (L.), fungal pathogen, Entomophaga maimaiga Humber, Shimazu & Soper. Lepidopteran larvae were reared from 7 plots in Virginia in which moderate density gypsy moth populations simultaneously exhibited from 40.8 to 97.5% E. maimaiga infection. From a total of 1,511 larvae from 52 species belonging to 7 lepidopteran families in 4 superfamilies, only 2 individuals, 1 of 318 forest tent caterpillars, Malacosoma disstria Hiibner (0.3% infection), and 1 of 96 Catocala ilia (Cramer) (1.0% infection), became infected by entomophthoralean pathogens. Results from genomic DNA probes and bioassays confirmed that E. maimaiga had caused these infections. Laboratory studies yielded infection over a greater diversity of species, and percentages of infection from laboratory studies were higher than findings from the field for the 1 species infected in both the laboratory and field. At all sites, the gypsy moth nuclear polyhedrosis virus also was found, occasionally causing epizootics, but viral occlusion bodies were never found in nontarget Lepidoptera that died. In addition, 279 nontarget Lepidoptera belonging to 34 species in 8 families were collected and reared from areas with low density native gypsy moth populations, and E. maimaiga infections were not found in these nontarget hosts, although E. maimaiga was active in gypsy moth populations. A survey of lepidopteran cadavers collected from 1989 to 1995 containing entomophthoralean spores documented E. maimaiga infections in 3 species of lymantriids. The Lepidoptera-specific North American endemic entomopathogen Entomophaga Aulicae (Reichardt in Bail) Humber, which is morphologically identical to E. maimaiga, was found in 1 geometrid species, 1 notodontid, 2 species of arctiids, and 1 introduced lymantriid, but in none of the gypsy moth larvae tested. Our results demonstrate that data from laboratory bioassays are poor estimates for predicting nontarget impact.
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A disjunct Californian strain of Entomophaga Aulicae infecting Orgyia vetusta.
Journal of invertebrate pathology, 1996Co-Authors: Ann E. Hajek, Donald R Strong, Scott Walsh, Julie C. SilverAbstract:Fungal epizootics occurred in abundant Orgyia vetusta (western tussock moth; Lepidoptera: Lymantriidae) populations on Lupinus arboreus bushes growing on the Pacific coast north of San Francisco, California. The causative pathogen was isolated and identified as Entomophaga Aulicae, Group II, based on RFLPs using rDNA and PCR-amplified rDNA products. Inability of this fungus to infect the lymantriid Lymantria dispar (gypsy moth) confirmed its distinction from Entomophaga maimaiga, the only other member of this species complex which predominantly infects lymantriids. Later instar wandering by O. vetusta in outbreak populations and close proximity of larvae in dense populations are characteristics most probably promoting development of E. Aulicae epizootics; these life history patterns are also typical of Lymantria dispar populations experiencing epizootics of E. maimaiga.
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Sympatric occurrence of two Entomophaga Aulicae (Zygomycetes : Entomophthorales) complex species attacking forest lepidoptera
Journal of Invertebrate Pathology, 1991Co-Authors: Richard A. Humber, Scott Walsh, Julie C. SilverAbstract:Abstract Entomophthoralean fungi caused infections in sympatric larval populations of Lymantria dispar and Heterocampa guttivitta in New York and Vermont during 1989 and 1990. Gross morphology as well as restriction fragment length polymorphism and allozyme analyses determined that the Japanese fungus Entomophaga maimaiga was responsible for L. dispar mortality, while a different and otherwise unidentified member of the E. Aulicae species complex was responsible for H. guttivitta mortality. Bioassays confirmed that the fungus infecting H. guttivitta was not E. maimaiga; the fungal isolate from H. guttivitta could not infect L. dispar larvae.
Claudia Lopez C Lastra - One of the best experts on this subject based on the ideXlab platform.
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survival and differential development of Entomophaga maimaiga and Entomophaga Aulicae zygomycetes entomophthorales in lymantria dispar hemolymph
Journal of Invertebrate Pathology, 2001Co-Authors: Claudia Lopez C Lastra, Donna M Gibson, Ann E. HajekAbstract:The closely related entomophthoralean fungi Entomophaga Aulicae and E. maimaiga are both host-specific pathogens of lepidopteran larvae. However, these fungi do not have the same host range. The first objective of this study was to compare the fate of E. Aulicae in the nonpermissive host Lymantria dispar with the fate of the successful pathogen E. maimaiga over the same time period. In the hemolymph of L. dispar injected with E. maimaiga protoplasts, the number of hemocytes demonstrated a decreasing trend after the first day postinjection and hemocytes completely disappeared by day 5, with the majority of larvae dying in 5.6 ± 0.1 days. In L. dispar larvae, E. maimaiga infections developed successfully, evidenced by increasing numbers of protoplasts and hyphal bodies prior to host mortality. In contrast, at day 5 hemocytes were readily visible in hemolymph of E. Aulicae-injected larvae, but E. Aulicae cells did not increase in numbers, although persisting in the hemolymph for at least 16 days postinjection. For both fungal species, when hemolymph samples from injected insects were introduced to culture media viable fungal cultures were always produced. Both E. Aulicae and E. maimaiga occurred in hemolymph initially after injection as protoplasts. For E. maimaiga, after day 3, <50% of fungal cells were hyphal bodies until insect death when most cells regenerated cell walls. For E. Aulicae, from day 2 equal numbers of fungal cells in the hemolymph occurred as protoplasts and hyphal bodies. To investigate the cause of fungistasis in E. Aulicae-injected larvae, E. Aulicae cell cultures exposed to partially purified protein fractions from hemolymph of larvae infected with either fungus displayed increased lysis and decreased viability at lower concentrations of protein fractions compared with E. maimaiga cell cultures. These studies demonstrate that E. Aulicae does not increase in L. dispar hemolymph, although it persists and results suggest that proteinaceous factors induced within the hemolymph may limit the capacity of E. Aulicae to develop successful infections.