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Randy Gaugler - One of the best experts on this subject based on the ideXlab platform.
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characterization of immunosuppressive surface coat proteins from Steinernema glaseri that selectively kill blood cells in susceptible hosts
Molecular and Biochemical Parasitology, 2009Co-Authors: Elizabeth Cowles, Randy Gaugler, Richard S Cowles, Diana L CoxfosterAbstract:Surface coat proteins (SCPs) of entomopathogenic nematodes are implicated in the suppression/evasion of host immune responses, which is required for successful host colonization. Steinernema glaseri NC strain SCPs suppressed immune responses in oriental beetle larvae (Exomala orientalis), a susceptible host for S. glaseri, in a dosage-dependent manner, thus protecting Heterorhabditis bacteriophora from being killed in the same host. Melanization of H. bacteriophora decreased from 92 ± 5% in the untreated check to 1 ± 3% when protected by injection of 230 ng of S. glaseri SCPs. As the SCPs dosage increased, freely moving H. bacteriophora increased from 3 ± 4% in the untreated group to 57 ± 15% with an SCPs dose of 940 ng. At 2 h and in the absence of SCPs, 8% and 11% of hemocytes of E. orientalis were stained by propidium iodide and Hoechst, respectively. When exposed to 300 ng/l SCPs, 70% and 96% were stained, respectively. At 6 h, propidium iodide stained 37% and 92% of the hemocytes without and with SCPs, respectively. In contrast, more than 90% of the cells were stained by Hoechst with or without SCPs. As native proteins, two isolated S. glaseri SCPs had an immunosuppressive effect; they were each composed of 38 kDa (PI = 4.6) and 56 kDa (PI = 3.6) subunits. SCP peptides were sequenced using LC-MS/MS and the mass fingerprints obtained with MALDI-TOF-MS; there were no significant matches found in peptide databases, which suggests that the SCPs studied are novel proteins. Twelve cDNA sequences were derived based on short peptides and 7 of them had no significant match against the Caenorhabditis elegans protein database. One of the cDNA matched an unknown C. elegans protein and the remaining 4 cDNAs matched proteins of C. elegans and Brugia malayi.
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host and penetration site location by entomopathogenic nematodes against japanese beetle larvae
Journal of Invertebrate Pathology, 1998Co-Authors: Yi Wang, Randy GauglerAbstract:Entomopathogenic nematodes are soil-inhabiting parasites of insects. Behavioral responses to host and host environmental cues are critical steps in the infection process for some nematode species, such as Steinernema glaseri and Heterorhabditis bacteriophora, of finding, recognizing, and penetrating insects. We investigated the impact of host and host environmental cues on the infectivity of these two nematodes by testing their response to whole and wounded grass roots and gut fluid and hemolymph of Popillia japanica larvae. We also compared the influence of root presence on infectivity. Infective juveniles of both nematode species migrated to whole and wounded grass roots, suggesting that these nematodes may use cues from grass roots and root wounds for host habitat finding. Root presence enhanced the infectivity of S. glaseri, presumably because feeding larvae ingest more nematodes than nonfeeding ones. However, the infectivity of H. bacteriophora was not enhanced by grub feeding. This may due to the weak gut penetration ability of this species. We conclude that the two species respond similarly to host and host environmental cues but achieve infection differently via penetration: S. glaseri possesses superior gut penetration ability, whereas intersegmental areas such as leg and maxilla joints serve as cuticle penetration sites for H. bacteriophora. Copyright 1998 Academic Press.
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response of infective stage parasites nematoda Steinernematidae to volatile cues from infected hosts
Journal of Chemical Ecology, 1997Co-Authors: Parwinder S. Grewal, Edwin E. Lewis, Randy GauglerAbstract:Volatile infochemicals play a significant role in the interactions between trophic levels. Volatile infochemicals may allow species within the third trophic level to avoid patches where conspecifics or heterospecifics are present. We show odor-mediated resource assessment by entomopathogenic nematodes in the family Steinernematidae. We hypothesized that the infective juvenile nematodes may reduce inter- and intraspecific competition by responding differently to unparasitized hosts vs. hosts parasitized by conspecific or heterospecific nematodes. All Steinernema spp. except S. carpocapsae were attracted to hosts that were not parasitized. Steinernema carpocapsae infective juveniles were repelled from hosts infected for 4 hr with all heterospecific infections except S. anomaliwhereas S. glaseri were repelled only from S. riobravis-infected hosts. Steinernema feltiae did not differentiate any heterospecific or heterogeneric infections. Steinernema glaseri were attracted to four of five heterospecific infections and S. anomali and S. riobravis were attracted to two of five heterospecific infections. Both S. anomali and S. glaseri were more attracted to hosts infected with the out-group Heterorhabditis bacteriophora than those infected by conspecific nematodes. Infective juvenile S. carpocapsae S. anomaliand S. glaseri were more attracted to insects colonized by conspecific nematodes than to uninfested insects. Infective juvenile S. carpocapsae were repelled from the 24-hr-old conspecific infections, whereas S. glaseri were less attracted to 24- than to 4-hr-old conspecific infections. Experiments with insects injected with bacteria from the nematodes suggested the latter as the source of active volatiles. We suggest that odor-mediated host recognition by infective juveniles may reduce inter- and intraspecific competition among Steinernematidae.
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infection of entomopathogenic nematodes Steinernema glaseri and heterorhabditis bacteriophora against popillia japonica coleoptera scarabaeidae larvae
Journal of Invertebrate Pathology, 1995Co-Authors: Yi Wang, James F. Campbell, Randy GauglerAbstract:Abstract Defense mechanisms of Japanese beetle larvae, Popillia japonica, and their effectiveness against entomopathogenic nematodes were investigated in the laboratory. Behavioral grooming by P. japonica larvae was effective in reducing invasion of both Steinernema glaseri and Heterorhabditis bacteriophora. Forty percent of H. bacteriophora infective juveniles were inactivated or killed in the host gut fluid within 8 hr, whereas 11% of S. glaseri were killed. Host melanotic encapsulation, induced by injection of 20 H. bacteriophora infective juveniles, caused 75% nematode mortality. S. glaseri was less susceptible to the host immune response, which caused only 12% mortality of injected nematodes. In a sand column assay, S. glaseri was found in the host hemocoel 8 hr earlier than H. bacteriophora. However, Photorhabdus luminescens, the bacterium of H. bacteriophora, was detected 16 hr earlier in the host's hemolymph than S. glaseri's bacterium, Xenorhabdus poinarii. Despite the differences in effectiveness of host defenses, S. glaseri and H. bacteriophora caused similar host mortality in the sand column assay. We demonstrated that the two nematode species use different strategies for invasion of P. japonica larvae. S. glaseri, which tolerated P. japonica gut fluid and avoided the host immune response, has a high initial rate of penetration and survival; H. bacteriophora, which exhibited poor tolerance to the host gut fluid and induced a strong host immune response, releases its bacteria during or soon after penetration to kill the host.
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entomopathogenic nematode rhabdita Steinernematidae sex ratio relates to foraging strategy
Journal of Invertebrate Pathology, 1994Co-Authors: Edwin E. Lewis, Randy GauglerAbstract:We demonstrate a relationship between the foraging strategies of entomopathogenic nematodes and the pattern of emergence of male.and female infective juveniles from their host. We hypothesize that protandry as a mating strategy may be most adaptive in situations where cruising search is employed to find hosts. Alternatively, when attachment to a host is more passive, as in ambush foraging, a more constantly female-biased sex ratio should be maintained. Cruise-foraging infective juvenile Steinernema glaseri that develop into adult males emerge from host cadavers before those that develop into females and are immediately sensitive to volatile host cues. Females that emerge later are less attracted to host volatiles than are males during the first week of the infective stage. However, recently emerged females are strongly attracted to parasitized hosts. Infective juvenile Steinernema carpocapsae showed the opposite trend, with significantly more females emerging on the first day than the later harvest. In most protandrous mating systems, males take the risks of colonizing a new resource. The benefit derived by the early males is to have prolonged access to females inside the new host. Females penetrate into the safer parasitized hosts to find males. Their chances of prereproductive death are decreased in two ways; males prepare the host by breaking down defenses, and males make it possible for the females to mate immediately when they reach adulthood. Reported variability between harvests of S. glaseri may be partially attributed to protandry.
Albrecht M Koppenhofer - One of the best experts on this subject based on the ideXlab platform.
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cultivation and domestication of highbush blueberry vaccinium corymbosum alters abundance diversity and virulence of entomopathogenic nematodes
Agriculture Ecosystems & Environment, 2016Co-Authors: Monique J Rivera, Cesar Rodriguezsaona, David E Jennings, Andrea Egizi, Dina M Fonseca, Albrecht M KoppenhoferAbstract:Abstract We investigated the interactive effect of plant domestication and perennial cultivation on abundance, diversity and virulence of entomopathogenic nematodes (EPN) associated with highbush blueberry (Vaccinium corymbosum). The rhizospheric soil of V. corymbosum plants was sampled in coupled wild and cultivated sites within the Pinelands National Reserve, New Jersey, USA from 2011 to 2013 at three points during each year. To isolate and assess abundance of EPN communities, soil samples were baited with wax moth larvae (Galleria mellonella). A subsample of EPNs isolated from the soil was identified using molecular barcoding. The virulence of three native isolates against oriental beetle, Anomala orientalis, larvae was assessed at multiple densities of nematodes per host. A cursory assessment of EPN diversity was based on variation in molecular barcodes because many sequences could not be identified in the genomic database GenBank. The variation among barcodes suggested that diversity was higher in rhizospheric soil associated with wild plants than that of cultivated fields. Steinernema glaseri was the only EPN species able to be identified using molecular methods and was the only species isolated from the six cultivated fields with EPN presence. An interaction of environment, sampling point, and year explained significant differences in EPN abundance in 2011 and 2012 when soil samples were assessed by plant. However, in 2013, soil was assessed by field rather than plant and our results show EPN abundance was higher in cultivated than in wild sites. Soil nutrients and characteristics were also assessed in 2013. A PCA analysis of soil characteristics linked higher plant nutrients to soil from cultivated fields and higher soil moisture, organic matter, boron and lower pH to wild plant-associated soil. In this study, cultivation of domesticated V. corymbosum increases the abundance of the more virulent EPN species against the presumed host, A. orientalis but appears to eliminate genetic variability from the EPN community.
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host density effects on efficacy of entomopathogenic nematodes against white grub coleoptera scarabaeidae species
Biocontrol Science and Technology, 2012Co-Authors: Lemma Ebssa, Eugene M. Fuzy, Matthew Bickerton, Albrecht M KoppenhoferAbstract:Abstract We tested the effect of host density on entomopathogenic nematode efficacy in 1-L pots with grass and soil. In four experiments, combinations ranged from somewhat resistant hosts (oriental beetle, Anomala orientalis, or northern masked chafer, Cyclocephala borealis, with Heterorhabditis bacteriophora) over more susceptible hosts (Japanese beetle, Popillia japonica, with Steinernema glaseri) to a highly susceptible host (P. japonica and S. scarabaei). In each experiment, four larval densities were exposed to two nematode rates over a 14-day period. A significant effect of host density on nematode efficacy occurred only in the A. orientalis–H. bacteriophora combination, but there was no clear trend in the data. This suggests that an exhaustion of available nematode populations to less lethal levels by high host numbers was counteracted by other factors such as increased chances for nematode-host contact and increased host susceptibility due to stress via reduced food resources and increased aggress...
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attraction of four entomopathogenic nematodes to four white grub species
Journal of Invertebrate Pathology, 2008Co-Authors: Albrecht M Koppenhofer, Eugene M. FuzyAbstract:To better understand the differences in the efficacy of entomopathogenic nematode species against white grub species, we are studying the various steps of the infection process of entomopathogenic nematodes into different white grub species using nematode species/strains with particular promise as white grub control agents. In this study we compared the attraction of the entomopathogenic nematodes Steinernema scarabaei (AMK001 strain), Steinernema glaseri (NC1 strain), Heterorhabditis zealandica (X1 strain), and Heterorhabditis bacteriophora (GPS11 strain) to third-instars of the scarabs Popillia japonica, Anomala orientalis, Cyclocephala borealis, and Rhizotrogus majalis, and late-instar greater wax moth, Galleria mellonella, larvae. Individual larvae were confined at the bottom of 5.5 cm vertical sand columns, nematodes added to the sand surface after 24 h, and nematodes extracted after another 24 h. Nematode attraction to hosts was strongly affected by nematode species but the effect of insect species varied with nematode species. S. glaseri had a high innate dispersal rate (i.e., in absence of insects) and was strongly attracted to insects without significant differences among insect species. S. scarabaei had a very low innate dispersal rate so that even a strong relative response to insects resulted in low absolute dispersal rates toward insects. S. scarabaei tended to be most attracted to G. mellonella and least attracted to C. borealis. H. zealandica had a high innate dispersal rate but only responded weakly to insects without significant differences among species. H. bacteriophora had limited innate dispersal and only weakly responded to insects with G. mellonella tending to be the most attractive and C. borealis the least attractive insect. It has to be noted that we cannot exclude that the use of different rearing hosts (A. orientalis and P. japonica larvae for S. scarabaei, G. mellonella larvae for the other nematodes) might have had an impact on the nematodes dispersal and relative attraction behavior. This study indicates that host attractiveness and nematode dispersal rates may contribute but do not play a major role in the variability in white grub susceptibility and/or nematode virulence.
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effect of soil type on infectivity and persistence of the entomopathogenic nematodes Steinernema scarabaei Steinernema glaseri heterorhabditis zealandica and heterorhabditis bacteriophora
Journal of Invertebrate Pathology, 2006Co-Authors: Albrecht M Koppenhofer, Eugene M. FuzyAbstract:We tested the effect of soil type on the performance of the entomopathogenic pathogenic nematodes Steinernema scarabaei, Steinernema glaseri, Heterorhabditis zealandica, and Heterorhabditis bacteriophora. Soil types used were loamy sand, sandy loam, loam, silt loam, clay loam, acidic sand, and a highly organic potting mix. Infectivity was tested by exposing third-instar Anomala orientalis or Popillia japonica to nematodes in laboratory and greenhouse experiments and determining nematode establishment in the larvae and larval mortality. Infectivity of H. bacteriophora and H. zealandica was the highest in potting mix, did not differ among loamy sand and the loams, and was the lowest in acidic sand. Infectivity of S. glaseri was significantly lower in acidic sand than in loamy sand in a laboratory experiment but not in a greenhouse experiment, and did not differ among the other soils. Infectivity of S. scarabaei was lower in silt loam and clay loam than in loamy sand in a greenhouse experiment but not in a laboratory experiment, but was the lowest in acidic sand and potting mix. Persistence was determined in laboratory experiments by baiting nematode-inoculated soil with Galleria mellonella larvae. Persistence of both Heterorhabditis spp. and S. glaseri was the shortest in potting mix and showed no clear differences among the other substrates. Persistence of S. scarabaei was high in all substrates and its recovery declined significantly over time only in clay loam. In conclusion, generalizations on nematode performance in different soil types have to be done carefully as the effect of soil parameters including soil texture, pH, and organic matter may vary with nematode species.
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effect of white grub developmental stage on susceptibility to entomopathogenic nematodes
Journal of Economic Entomology, 2004Co-Authors: Albrecht M Koppenhofer, Eugene M. FuzyAbstract:The pathogenicity of the entomopathogenic nematodes Heterorhabditis bacteriophora Poinar and Steinernema scarabaei Stock & Koppenhofer against different developmental stages of the Japanese beetle, Popillia japonica Newman, and the oriental beetle, Anomala (=Exomala) orientalis Waterhouse, were studied under laboratory conditions. The efficacy of S. scarabaei did not differ between second and third instars in P. japonica or A. orientalis or between small (young) and large (older) third instars in A. orientalis. However, H. bacteriophora efficacy decreased from first over second to third instar and also from small third instars to large third instars in A. orientalis but did not differ significantly between P. japonica larval stages. Once A. orientalis third instars had purged their intestines in preparation for pupation, no significant mortality by S. scarabaei and H. bacteriophora was observed. In contrast, P. japonica susceptibility to both nematode species gradually decreased from stage to stage from actively feeding third instars to pupae. In two additional experiments, we found no difference in Steinernema glaseri (Steiner) susceptibility between second and third instars of A. orientalis but an increase in S. scarabaei susceptibility from the second to third instar of Asiatic garden beetle, Maladera castanea (Arrow). Our observations combined with those of previous studies with other nematode and white grub species show that nematode efficacy against white grub developmental stages varies with white grub and nematodes species, and no generalization can be made.
Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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host and penetration site location by entomopathogenic nematodes against japanese beetle larvae
Journal of Invertebrate Pathology, 1998Co-Authors: Yi Wang, Randy GauglerAbstract:Entomopathogenic nematodes are soil-inhabiting parasites of insects. Behavioral responses to host and host environmental cues are critical steps in the infection process for some nematode species, such as Steinernema glaseri and Heterorhabditis bacteriophora, of finding, recognizing, and penetrating insects. We investigated the impact of host and host environmental cues on the infectivity of these two nematodes by testing their response to whole and wounded grass roots and gut fluid and hemolymph of Popillia japanica larvae. We also compared the influence of root presence on infectivity. Infective juveniles of both nematode species migrated to whole and wounded grass roots, suggesting that these nematodes may use cues from grass roots and root wounds for host habitat finding. Root presence enhanced the infectivity of S. glaseri, presumably because feeding larvae ingest more nematodes than nonfeeding ones. However, the infectivity of H. bacteriophora was not enhanced by grub feeding. This may due to the weak gut penetration ability of this species. We conclude that the two species respond similarly to host and host environmental cues but achieve infection differently via penetration: S. glaseri possesses superior gut penetration ability, whereas intersegmental areas such as leg and maxilla joints serve as cuticle penetration sites for H. bacteriophora. Copyright 1998 Academic Press.
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infection of entomopathogenic nematodes Steinernema glaseri and heterorhabditis bacteriophora against popillia japonica coleoptera scarabaeidae larvae
Journal of Invertebrate Pathology, 1995Co-Authors: Yi Wang, James F. Campbell, Randy GauglerAbstract:Abstract Defense mechanisms of Japanese beetle larvae, Popillia japonica, and their effectiveness against entomopathogenic nematodes were investigated in the laboratory. Behavioral grooming by P. japonica larvae was effective in reducing invasion of both Steinernema glaseri and Heterorhabditis bacteriophora. Forty percent of H. bacteriophora infective juveniles were inactivated or killed in the host gut fluid within 8 hr, whereas 11% of S. glaseri were killed. Host melanotic encapsulation, induced by injection of 20 H. bacteriophora infective juveniles, caused 75% nematode mortality. S. glaseri was less susceptible to the host immune response, which caused only 12% mortality of injected nematodes. In a sand column assay, S. glaseri was found in the host hemocoel 8 hr earlier than H. bacteriophora. However, Photorhabdus luminescens, the bacterium of H. bacteriophora, was detected 16 hr earlier in the host's hemolymph than S. glaseri's bacterium, Xenorhabdus poinarii. Despite the differences in effectiveness of host defenses, S. glaseri and H. bacteriophora caused similar host mortality in the sand column assay. We demonstrated that the two nematode species use different strategies for invasion of P. japonica larvae. S. glaseri, which tolerated P. japonica gut fluid and avoided the host immune response, has a high initial rate of penetration and survival; H. bacteriophora, which exhibited poor tolerance to the host gut fluid and induced a strong host immune response, releases its bacteria during or soon after penetration to kill the host.
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penetration of Steinernematid nematodes nematoda Steinernematidae into japanese beetle larvae popillia japonica coleoptera scarabaeidae
Journal of Invertebrate Pathology, 1993Co-Authors: Randy Gaugler, Yi WangAbstract:Abstract Penetration of infective juveniles of Steinernema glaseri and Steinernema carpocapsae into Japanese beetle larvae, Popillia japonica , was compared using external exposure and injection methods. Steinernematids entered the grubs through the mouth and anus, but not through the spiracles or cuticle. For all treatments, S. glaseri had higher levels of penetration than S. carpocapsae . Penetration of the gut by orally injected nematodes began 4-6 hr postinoculation. All regions of the gut were penetrated, with more than 82% of all penetrating nematodes invading the host hemocoel via the midgut. Gastric cecae were important sites for nematode penetration. Penetration sites of anally injected nematodes were the rectal sac of the hindgut. Penetration rates of isolated guts and that in vivo did not differ. Defecation by P. japonica was rapid, with orally injected nematodes appearing in the feces in 4-8 hr. Our results indicate that compared with S. glaseri, S. carpocapsae is poorly adapted to parasitize Japanese beetle larvae.
Raquel Camposherrera - One of the best experts on this subject based on the ideXlab platform.
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long term stability of entomopathogenic nematode spatial patterns in soil as measured by sentinel insects and real time pcr assays
Annals of Applied Biology, 2011Co-Authors: Raquel Camposherrera, Evan G Johnson, Fahiem E Elborai, Robin J Stuart, J H Graham, L W DuncanAbstract:Quantitative real-time PCR (qPCR) techniques are being increasingly used to provide accurate and reliable methods to identify and quantify cryptic organisms in soil ecology. Entomopathogenic nematode (EPN) diversity in Florida is known to be extensive and our phylogenetic studies of the D2D3 and ITS regions showed the occurrence of an additional species-complex in the Steinernema glaseri- group in widely separated locations of the peninsula. To address ecological studies, we developed and used qPCR assays to detect and quantify six species of EPN that are naturally distributed in Florida citrus orchards (Steinernema diaprepesi, Steinernema riobrave, Heterorhabditis indica, Heterorhabditis zealandica, Heterorhabditis floridensis and an undescribed species in the S. glaseri group) and an exotic species, S. glaseri. Species-specific primers and TaqMan ® probes were designed from the ITS rDNA region. No nonspecific amplification was observed in conventional or qPCR when the primers and probes were tested using several populations of each of the Florida species and other exotic EPN species. Standard curves were established using DNA from pure cultures. We optimised a protocol for extracting nematodes and DNA from soil samples that can detect one EPN added to nematode communities recovered by conventional extraction protocols. A survey of an 8-ha orchard in April 2009 compared the EPN spatial patterns derived from qPCR to that obtained by baiting soil samples with Galleria mellonella larvae. The patterns were also compared to those derived from the same site in 2000-01 by repeatedly (12 sampling events) baiting soil in situ with caged larvae of the root weevil Diaprepes abbreviatus. The qPCR assay was more efficient than the Galleria baiting method for detecting the EPN species composition in population mixtures. Moreover, the spatial patterns of EPN in this orchard were remarkably stable over the course of nearly a decade. The pattern of H. zealandica detected at the site 8 years earlier was related to those derived by qPCR (P = 0.002) and from sample baiting (P = 0.02). The spatial pattern of H. indica derived from qPCR, but not that from sample baiting, was also related to the earlier pattern (P = 0.01). The qPCR assay developed here is a fast, affordable and accurate method to detect and quantify these EPN species in soil and offers great potential for studying the ecology of EPN.
E. R. Silva - One of the best experts on this subject based on the ideXlab platform.
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Compatibility between the entomopathogenic nematode Steinernema glaseri (Rhabditida: Steinernematidae) and an acaricide in the control of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)
Parasitology Research, 2008Co-Authors: C. M. R. Reis-menini, M. C. A. Prata, J. Furlong, E. R. SilvaAbstract:There have been studies of the compatibility between entomopathogenic nematodes and insecticides commonly used to control crop pests, but this same approach has not been widely studied regarding the control of ticks. Therefore, this work examines the association between a species of entomopathogenic nematode, Steinernema glaseri , and an organophosphate acaricide to control the cattle tick Rhipicephalus microplus . Engorged females were separated into 12 groups, with ten repetitions each, immersed for 5 min in varied concentrations of acaricide (commercial dose and one-half, one-fourth, one-eighth and one-sixteenth of that dose), associated or not with the nematodes, maintained under controlled conditions. There were two control groups, one containing nematodes and water and the other only water. The absence of egg laying and significant reduction in the survival period of the females in the nematode treatments associated with the lowest acaricide doses demonstrated the compatibility between the two agents. We observed the presence of S. glaseri adults on the cuticle of the females in the treatments with one-eighth and one-sixteenth the commercial dose. These results indicate greater efficacy of the treatments with lower acaricide concentrations in association with S. glaseri , with less environmental impact, reduced costs and less resistance selection pressure on the tick populations.