Efficacy of commercially available entomopathogenic nematodes against insect pests of canola in Alberta, Canada.

Certain entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are among the most studied biocontrol tools, some of which are commercially available against pest insects. Their use against foliar and subterranean insect pests is largely unexplored in the Canadian Prairies. We conducted a laboratory-based study to produce baseline information on the biocontrol potential of a few commercial EPN species. Percent mortality of flea beetles, diamondback moths (DBMs), lygus, cabbage root maggots, and black cutworms (BCWs) was assessed after 72 hours exposure to Steinernema carpocapsae, S. kraussei, S. feltiae, and Heterorhabditis bacteriophora at varying concentrations (25, 50, 100, and 200 infective juveniles (IJs) per larvae, pupae, or cm2 of soil surface). Irrespective of concentration level, S. carpocapsae and S. kraussei caused significant mortality in DBM and BCW larvae compared with H. bacteriophora.S. kraussei, and S. feltiae were more efficient than S. carpocapsae in controlling root maggot larvae. H. bacteriophora caused zero mortality to root maggots at any concentration. Root maggot pupae were resistant to entry to EPN species tested, likely due to hard outer covering. Compared with root maggot pupae, a moderate level of mortality was observed in DBM pupae, suggesting differential ability of the tested EPNs in killing different life stages of certain pests. All nematode species tested caused low mortality (≤10%) in flea beetle adults. The findings of this investigation form fundamental data essential for carrying out field-based studies on canola and other related crops aimed at control and management of these pest species.

Metabarcoding study to reveal the structural community of strongylid nematodes in domesticated horses in Thailand.

BACKGROUND: Mixed strongylid infections significantly impact equine health and performance. Traditional microscopy-based methods exhibit limitations in accurately identifying strongylid species. Nemabiome deep amplicon sequencing approach previously succeeded in describing the strongylid communities in livestock including equids. However, there are no available studies that describe the structural communities of strongylid parasites in horses in Thailand. Therefore, this study was undertaken encompassing the ITS-2 rDNA metabarcoding assay to characterize strongylid species within horse fecal samples collected from a cohort of yearlings at the largest domesticated stud farm in Thailand. In addition, to investigate the capability of ITS-2 rDNA in assessing the phylogenetic relationships among the identified strongylid species. RESULTS: The study identified 14 strongylid species in the examined equine populations, each with varying prevalence. Notably, Cylicocyclus nassatus and Cylicostephanus longibursatus were identified as the predominant species, with Strongylus spp. conspicuously absent. The phylogenetic analysis of 207 amplicon sequence variants (ASVs) displayed a complex relationship among the investigated cyathostomin species, with some species are positioned across multiple clades, demonstrating close associations with various species and genera. CONCLUSION: The ITS-2 nemabiome sequencing technique provided a detailed picture of horse strongylid parasite species in the studied population. This establishes a foundation for future investigations into the resistance status of these parasites and enables efforts to mitigate their impact.

Gastrointestinal parasite community structure in horses after the introduction of selective anthelmintic treatment strategies.

A relatively new method to study the species richness and diversity of nematode parasites in grazing animals is to perform deep sequencing on composite samples containing a mixture of parasites. In this work, we compared species composition of strongyles in two groups of horses as a function of egg count and age, based on a DNA barcoding approach. Faecal egg counts and larval cultures were obtained from nearly 300 horses, i.e., domestic horses (n = 167) and trotters (n = 130) sampled nationwide. The second internal transcribed spacer region (ITS2) of strongyle nematodes in the larval cultures was first amplified using barcoded universal primers and then sequenced on the PacBio platform. Subsequently, bioinformatic sequence analysis was performed using SCATA to assign operational taxonomic units (OTU). Finally, species occurrence and composition were assessed using R. ITS2 sequences were found in the majority (89%) of larval samples. Sequencing yielded an average of 140 (26 to 503) reads per sample. The OTUs were assigned to 28 different taxa, of which all but three could be identified as species. The average relative abundance of the seven most abundant species (all Cyathostominae) accounted for 87% of the combined data set. The three species with the highest prevalence in both horse groups were Cyathostomum catinatum, Cylicocyclus nassatus and Cylicostephanus calicatus, and they were frequently found in different combinations with other species regardless of horse group. Interestingly, this result is largely consistent with a previous Swedish study based on morphological analysis of adult worms. In addition, two migratory strongylids (Strongylus vulgaris and S. edentatus) occurred in few domestic horses and trotters. Except for C. minutus and C. nassatus, which decreased with age, and C. catinatum and S. vulgaris, which increased, no specific trends were observed with respect to horse age. Taken together, these results are broadly consistent with data obtained before the introduction of selective targeted treatment in Sweden in 2007. All in all, our results suggest that this treatment strategy has not led to a significant change in strongyle nematode community structure in Swedish horses. The study also confirms that nemabiome analysis in combination with diversity index analysis is an objective method to study strongyle communities in horses.

Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding.

This study reports the spatial and temporal distribution of ascarid and strongylid nematodes in Thoroughbred horses by age category across different climatic zones in Australia over an 18-month period. Faecal samples (n = 2046) from individual horses were analysed using the modified McMaster technique for faecal egg counts (FECs). Strongylids were identified using PCR-directed next-generation sequencing of the second internal transcribed spacer (ITS-2) of the nuclear ribosomal DNA. Yearlings had the highest prevalence (82%) of strongyle eggs followed by weanlings (79%), foals (58%), wet mares (49%) and dry mares (46%). For Parascaris spp., foals had the highest prevalence (35%) followed by weanlings (21%) and yearlings (10%). The highest mean FECs for Parascaris spp. were observed in foals (525 eggs per gram [EPG] of faeces) while those for strongyles were in yearlings (962 EPG). Among horses that were classified as adults at the time of sampling, 77% (860 of 1119) of mares were low (i.e., <250 EPG) strongyle egg-shedders. Mean strongyle FEC counts were highest in the Mediterranean (818 EPG) followed by summer (599 EPG), winter (442 EPG), and non-seasonal (413 EPG) rainfall zones. Twenty-six nematode species were detected, with Cylicostephanus longibursatus (26.5%), Cylicocyclus nassatus (23.7%) and Coronocyclus coronatus (20.5%) being the most frequently detected species. Their richness and relative abundance varied with horse age, season and climatic zone. In addition, Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus) were also detected. This comprehensive study elucidates spatial (climatic zone) and temporal (i.e., seasonal) trends in prevalence and burdens of intestinal nematodes in Australian horses using non-invasive conventional and molecular methods. The information presented in this study is crucial for developing integrated management strategies to control horse parasites in farmed horses.

Demonstration of reduced efficacy against cyathostomins without change in species composition after pyrantel embonate treatment in Swedish equine establishments.

Consisting of approximately 50 different species, the cyathostomin parasites are ubiquitous in grazing horses. Co-infection with several species is common, and large burdens can cause the fatal disease of larval cyathostominosis. Due to intense anthelmintic drug use, cyathostomin resistance has developed to all available anthelmintic drug groups. Resistance to the anthelmintic drug pyrantel (PYR) has been documented in over 90% of studies published over the past two decades. In Sweden, a study performed in the early 2000s only confirmed resistance in 4.5% of farms. Further, prescription-only administration of equine anthelmintic drugs was enforced in Sweden in 2007. However, it is unknown if this conservative drug use has maintained PYR efficacy in cyathostomins. The aim of the present study was to investigate the effect of PYR on cyathostomin infection in Sweden using fecal egg count reduction tests (FECRTs). Further, the effect of PYR treatment on cyathostomin species composition was studied using metabarcoding. Sixteen farms with at least six horses excreting a minimum of 100 eggs per gram feces were included. Using the current World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines, PYR resistance was demonstrated in nine of farms, with seven farms showing full susceptibility. Farms with low biosecurity measures had significantly lower efficacy of PYR treatment. The most common cyathostomin species were Cylicocyclus nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, Cys. calicatus, Cys. goldi, Cys. minutus, Coronocyclus coronatus and Cya. pateratum, accounting for 97% of all sequence reads prior to treatment. Of these, Cyc. nassatus and Cya. catinatum had the highest occurrence, accounting for 68% of all sequence reads prior to PYR treatment. Treatment did not significantly affect the species composition. The results highlight the importance of drug efficacy testing when using PYR to treat cyathostomin infection, even when selective anthelmintic treatment and thus low treatment intensity, is used on the farm.

Equine Strongylidae and other parasitic nematodes described by Arthur Looss during 1895-1911 in the collections of the Swedish Museum of Natural History.

Prof. Arthur Looss (1861-1923) was a prolific German parasitologist, who, among other things, authored descriptions of 22 new species of nematodes and 115 new species of trematodes. After his death, his collection (including type material) was split between several institutions: Smithsonian National Museum of Natural History in Washington (USA), Natural History Museum in Berlin and the Natural History Museum in Leipzig (Germany), Gothenburg Museum of Natural History and Swedish Museum of Natural History (Sweden). Here we revise all type specimens of nematodes from the A. Looss collection that are currently preserved in the Swedish Museum of Natural History (Strongylus subtilis, Sclerostomum edentatum, S. vulgare, Cyathostomum labratum, C. coronatum, C. bicoronatum, C. calicatum, C. alveatum, C. catinatum, C. nassatum, C. radiatum, C. elongatum, C. auriculatum, Triodontus minor, T. serratus, C. labiatum and Uncinaria polaris), designate and describe lectotypes wherever deemed necessary and provide catalogue access numbers to all type materials. We also revise all notes and drawings associated with new species that A. Looss described and provide previously unpublished pencilled sketches and ink print-ready drawings of some of these species (Strongylus subtilis, Cyathostomum poculatum, C. radiatum, C. elongatum, C. calicatum, C. auriculatum, Triodontus serratus, Trichostrongylus vitrinus and possibly Necator africanus).

Gastro-intestinal and Respiratoric System Helminths of Domestic Geese in Samsun and Districts

Objective: This research was carried out to determine the digestive and respiratory system helminths of domestic geese collected from Canik, Çarsamba, Havza, Kavak, Terme, and Tekkeköy districts representing Samsun province. Methods: Within the scope of the study, the digestive and respiratory system organs of 64 domestic geese were collected. Organ sets were taken separately, and the contents of each organ were examined. Results: According to macroscopic and microscopic examination, 5 different helminth species were detected in 53 (82.8%) geese: Baruscapillaria obsignata (59.4%), B. anseris (32.8%), Amidostomum anseris (9.4%), Trichostrogylus tenuis (1.6%), and Heterakis sp. (1.6%). Conclusion: At the end of the study, all helminths were found in the digestive system and all of them were nematods. In conclusion, it has been predicted that nematodes that settle in the digestive system of geese are frequently encountered and this may be a problem for goose breeders.

Molecular diagnostics for gastrointestinal helminths in equids: Past, present and future.

This review is aimed to (i) appraise the literature on the use of molecular techniques for the detection, quantification and differentiation of gastrointestinal helminths (GIH) of equids, (ii) identify the knowledge gaps and, (iii) discuss diagnostic prospects in equine parasitology. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews, we retrieved 54 studies (horses: 50/54; donkeys and zebras: 4/54) from four databases. Polymerase chain reaction (PCR) was employed in all of the studies whereas PCR amplicons were sequenced in only 18 of them. Other techniques used (including modifications of PCR) were reverse line blot, quantitative (q)PCR, restriction fragment length polymorphism, nested-PCR, PCR-directed next-generation sequencing, Southern blotting, single strand conformation polymorphism, PCR-enzyme linked immunosorbent assay, matrix-assisted laser desorption/ionisation-time of flight and random amplification of polymorphic DNA. Most of the studies (53/54) used nuclear ribosomal RNA (including the internal transcribed spacers, intergenic spacer, 5.8 S, 18 S, 28 S and 12 S) as target loci while cytochrome c oxidase subunit 1 and random genomic regions were targeted in only three and one studies, respectively. Overall, to date, the majority of molecular studies have focused on the diagnosis and identification of GIHs of equids (i.e. species of Anoplocephala, Craterostomum, cyathostomins, Oesophagodontus, Parascaris, Strongylus, Strongyloides and Triodontophorus), with a recent shift towards investigations on anthelmintic resistance and the use of high-throughput nemabiome metabarcoding. With the increasing reports of anthelmintic resistance in equid GIHs, it is crucial to develop and apply techniques such as advanced metabarcoding for surveillance of parasite populations in order to gain detailed insights into their diversity and sustainable control. To the best of our knowledge, this is the first systematic review that evaluates molecular investigations published on the diagnosis and quantification of equid GIHs and provides useful insights into important knowledge gaps and future research directions in equid molecular parasitology.

Identifying 3rd larval stages of common strongylid and non-strongylid nematodes (class: Nematoda) infecting Egyptian equines based on morphometric analysis.

Strongylid and non-strongylid nematodes are one of the most important parasites infecting equines. The traditional method to identify these nematodes is through coproscopy and fecal culture. Because of the scarcity of data published in Egypt discussing the morphometric features of infective 3rd larvae of these nematodes, this study aims to provide a morphometric key for L3 of common strongylid and non-strongylid nematodes infecting Egyptian equines. For this reason, we cultured fecal samples containing GINs eggs and 3rd larval stages were identified based on their morphology (i.e., shape and number of intestinal cells (IC), shape of the esophagus, and shape of the tail sheath) in addition to computing their dimensions (i.e., length of larvae with sheath, length of the esophagus, length of intestinal cells, and body breadth). We identified 3rd larval stages of four strongylid nematodes (Cyathostomum sensu lato, Strongylus vulgaris, Strongylus equinus, and Strongylus edentatus) as well as two non-strongylid nematodes (Strongyloides westeri, and Trichostrongylus axei). Statistically, our results revealed significant differences in terms of total length, body width, esophagus length, and gut length among 3rd larvae identified in the current study. The combination of both morphological and metric keys will allow the better identification of common strongylid and non-strongylid nematodes infecting equines.

Anthelmintic resistance of gastrointestinal nematodes in goats: A systematic review and meta-analysis.

OBJECTIVE: To review anthelmintic resistance globally in goats including the effect of location, mode of application and dosage on anthelmintic efficacy (assessed using Faecal Egg Count Reduction). Specifically, resistance of the three major classes of anthelmintics - Benzimidazole and Probenzimidazole (BP); Anti-cholinergics (AC); and Macrocyclic Lactone (ML) was investigated. DESIGN/PROCEDURE: A PRISMA Framework was followed in order to conduct a thorough assessment of the literature on anthelmintic resistance in goats. A single factor ANOVA test was conducted in Microsoft Excel (2009) to test for the significance of the effect of location, mode of application and dosage on resistance. Three meta-analyses were also conducted in Microsoft Excel (2009) to quantify global resistance levels of the three major anthelmintic classes. RESULTS: Of the 461 publications screened, 105 studies were included in the systematic review and 101 studies were included in the meta-analyses. Anthelmintic class as well as anthelmintic active principle selection in the BP and ML classes did have a significant effect on resistance (p < 0.05). Combination treatment groups had a lower amount of resistance than groups where anthelmintic classes were used alone. Mode of application of the treatment had a significant effect on resistance (p < 0.05), whilst the correlation of dosage with efficacy was low (r < 0.1). The effect of location (by continent) also had a significant influence on resistance for the AC anthelmintic class (p < 0.05). All GIN species assessed with the exception of Chabertia spp. exhibited anthelmintic resistance. CONCLUSIONS: Anthelmintic resistance is a substantial global issue in the goat industry. More research needs to be conducted into anthelmintic resistance in regard to effective ways to use anthelmintics and minimise resistance.

Shortened egg reappearance periods of equine cyathostomins following ivermectin or moxidectin treatment: morphological and molecular investigation of efficacy and species composition.

Macrocyclic lactones have been the most widely used drugs for equine parasite control during the past four decades. Unlike ivermectin, moxidectin exhibits efficacy against encysted cyathostomin larvae, and is reported to have persistent efficacy with substantially longer egg reappearance periods. However, shortened egg reappearance periods have been reported recently for both macrocyclic lactones, and these findings have raised several questions: (i) are egg reappearance period patterns different after ivermectin or moxidectin treatment? (ii) Are shortened egg reappearance periods associated with certain cyathostomin species or stages? (iii) How does moxidectin's larvicidal efficacy affect egg reappearance period? To address these questions, 36 horses at pasture, aged 2-5 years old, were randomly allocated to three treatment groups: 1, moxidectin; 2, ivermectin; and 3, untreated control. Strongylid fecal egg counts were measured on a weekly basis, and the egg reappearance period was 5 weeks for both compounds. Strongylid worm counts were determined for all horses: 18 were necropsied at 2 weeks post-treatment (PT), and the remaining 18 at 5 weeks PT. Worms were identified to species morphologically and by internal transcribed spacer-2 (ITS-2) rDNA metabarcoding. Moxidectin and ivermectin were 99.9% and 99.7% efficacious against adults at 2 weeks post treatment, whereas the respective efficacies against luminal L4s were 84.3% and 69.7%. At 5 weeks PT, adulticidal efficacy was 88.3% and 57.6% for moxidectin and ivermectin, respectively, while the efficacy against luminal L4s was 0% for both drugs. Moxidectin reduced early L3 counts by 18.1% and 8.0% at 2 or 5 weeks, while the efficacies against late L3s and mucosal L4s were 60.4% and 21.2% at the same intervals, respectively. The luminal L4s surviving ivermectin treatment were predominantly Cylicocyclus (Cyc.) insigne. The ITS-2 rDNA metabarcoding was in good agreement with morphologic species estimates but suggested differential activity between moxidectin and ivermectin for several species, most notably Cyc. insigne and Cylicocyclus nassatus. This study was a comprehensive investigation of current macrocyclic lactone efficacy patterns and provided important insight into potential mechanisms behind shortened egg reappearance periods.

Faecal egg counts and nemabiome metabarcoding highlight the genomic complexity of equine cyathostomin communities and provide insight into their dynamics in a Scottish native pony herd.

Understanding the composition of gastrointestinal nematode communities may help to mitigate or exploit parasite adaptations within their host. We have used nemabiome deep amplicon sequencing of internal transcribed spacer-2 (ITS-2) ribosomal DNA to describe the temporal and host species composition of gastrointestinal nematode communities following sampling of six Scottish ponies across 57 months. In the absence of parasite control, each horse showed seasonal trends of increases and decreases in faecal egg counts, consistent with the epidemiology of equine strongylid parasites, however, the composition of parasites within individuals changed over time. Sixteen presumptive strongylid species were identified in each of the horses, 13 of which were distributed in a complex clade together with small numbers of amplicon sequences which could not be classified beyond the Cyathostominae subfamily level. Egg shedding of seven trichostrongylid species, which had previously been identified in co-grazed Soay sheep, was identified during the early spring. Faecal egg counts and the percentage of amplicon sequences assigned to each gastrointestinal nematode species were combined to describe their relative abundance across both host and time. Significant differences in species diversity between horses and between months were observed, being greatest from March to May and least from October to December. The magnitude of the individual horse effect varied between months and, conversely, the magnitude of the seasonal effect varied between individual horses. The most abundant gastrointestinal nematode in each of the horses was Cylicostephanus longibursatus (46.6% overall), while the abundance of the other strongylid species varied between horses and relative to each other. Patent C. longibursatus infections over the winter months might represent a genetic adaptation towards longer adult worm survival, or a lower rate of developmental arrest in the autumn. This study provides insight into highly complex phylogenetic relationships between closely related cyathostomin species; and describes the dynamics of egg shedding and pasture contamination of co-infecting equine gastrointestinal nematode communities. The results could be applied to determine how climatic and management factors affect the equilibrium between hosts and their parasites, and to inform the development of sustainable gastrointestinal nematode control strategies for different host species.

Scanning electron microscopy of Quilonia renniei from Asian elephants revealing variation in coronal leaflet number.

Although parasitic nematodes in the genera Murshidia and Quilonia (family Strongylidae) are recognized as major gastrointestinal parasites in Asian elephants, they have been poorly studied. Recently, light micrographs of these parasites in Myanmar have been presented, almost 100 years after the original drawings. However, the number of coronal leaflets, a key taxonomic feature of Quilonia species, has not been precisely determined based on light microscopy. The current study aimed to determine the exact number of coronal leaflets in Quilonia renniei specimens from Asian elephants in Myanmar. On the basis of scanning electron micrographs, leaflet number in females (19­20, average 19.7, n = 9) was significantly higher (P < 0.005) than that in males (16­19, average 18.1, n = 8). This compares with 18 coronal leaflets indicated in the original species description. Specimens bearing 19 coronal leaflets were most numerous, followed by those with 20 leaflets. Median-joining network analysis of mitochondrial cytochrome c oxidase subunit I gene sequences with 16 haplotypes from 19 individuals revealed no clear association between parasite populations and the number of coronal leaflets. These results highlight the importance of determining the number of coronal leaflets in the taxonomy of Q. renniei and other related Quilonia species infecting Asian elephants.

Colour of heterorhabditis zealandica-infected-Galleria mellonella dependent on the Photorhabdus symbiont, with two new nematode-symbiotic associations reported.

Bacterial symbionts associated with entomopathogenic nematodes (EPNs) play an important role in terms of the insecticidal properties of nematodes in pest control. Galleria mellonella larvae, shortly after being infected with three different strains of Heterorhabditis zealandica, which were isolated from South African soil, changed from pale white to steel grey-blue (blue), bright red, and yellow with a green tint (green), respectively. The genetic relatedness of the bacterial symbionts that were isolated from the three strains of H. zealandica was determined by means of comparing the 16S rRNA, recA, gyrB, dnaN, gltX and infB gene sequences. Subsequently, comparing the concatenated sequences revealed the presence of three distinct Photorhabdus species. The H. zealandica strain SF41, associated with Photorhabdus heterorhabditis, produced 'blue' G. mellonella larvae. The H. zealandica strain MJ2C, associated with Photorhabdus thracensis, yielded 'green' G. mellonella larvae, while the H. zealandica strain LLM associated with Photorhabdus laumondii subsp. laumondii yielded red larvae. The colour changes in G. mellonella larvae were found to have been instigated by a particular Photorhabdus species associated with H. zealandica. The red and 'green' phenotypes of G. mellonella larvae were found to represent new combinations of Heterorhabditis and Photorhabdus. In future studies, the colour of infected G. mellonella larvae needs to be reported as a phenotypic character, as it indicates the different bacterial species associated with the same nematode host, as shown in the case of H. zealandica.

Reviving a tradition: The Development of Strongylus vulgaris in larval culture.

All horses are susceptible to the equine gastrointestinal parasite, Strongylus vulgaris, which is known to cause significant disease and death. The parasite undergoes development from the egg through the first (L1), second (L2) and third (L3) larval stages outside the horse. The L3 is the infective stage. The universally available technique for detection of S. vulgaris larvae is the larval culture method. This requires a 10-14 day culture period to induce development from egg to L3, followed by Baermannization and identification of the L3s to genus and/or species. It is unknown if the culture duration is necessary or ideal for S. vulgaris identification. The purpose of this study was to perform daily examinations of known S. vulgaris positive fecal samples in coproculture. Fresh feces were collected from a horse known to be shedding S. vulgaris eggs. A total of 140 cultures were set up using 10 g of feces. Cultures remained at room temperature and moistened every other day. Every day, 10 samples were examined, and all larvae were identified to stage, genus/species, and enumerated. Throughout the study, L1, L2, and L3 stages were observed, and S. vulgaris, Strongylus edentatus, Triodontophorus spp., and cyathostomin L3s were identified. Third stage larvae were observed on Day 5, and the mean number of L3s significantly increased on Day 10 (P < .001), and declined thereafter. Strongylus vulgaris was first observed on Day 6 with a mean count of 4.1 (95 % CI: 1.1, 7.1) S. vulgaris larvae, accounting for 4.1 % (95 % CI:1.8, 7) of the total L3s observed. The number of S. vulgaris larvae was significantly higher on Day 10 with a mean of 156.8 (95 % CI: 120.7, 192.9) S. vulgaris larvae (P < .001), and the proportion was also significantly higher with S. vulgaris comprising 50 % (95 % CI: 45.9, 54.8) (P = .006) of the total larvae. However, after 10 days, the mean number of S. vulgaris larvae declined, as did the proportion of S. vulgaris larvae compared to the total number of larvae. Using the described methods, it is possible to identify S. vulgaris as early as 6 days, and the optimal period is 10 days to detect the maximum number of S. vulgaris.

Phylogenetic relationships of the nematode subfamily Phascolostrongylinae from macropodid and vombatid marsupials inferred using mitochondrial protein sequence data.

BACKGROUND: The subfamily Phascolostrongylinae (Superfamily Strongyloidea) comprises nematodes that are parasitic in the gastrointestinal tracts of macropodid (Family Macropodidae) and vombatid (Family Vombatidae) marsupials. Currently, nine genera and 20 species have been attributed to the subfamily Phascolostrongylinae. Previous studies using sequence data sets for the internal transcribed spacers (ITS) of nuclear ribosomal DNA showed conflicting topologies between the Phascolostrongylinae and related subfamilies. Therefore, the aim of this study was to validate the phylogenetic relationships within the Phascolostrongylinae and its relationship with the families Chabertiidae and Strongylidae using mitochondrial amino acid sequences. METHODS: The sequences of all 12 mitochondrial protein-coding genes were obtained by next-generation sequencing of individual adult nematodes (n = 8) representing members of the Phascolostrongylinae. These sequences were conceptually translated and the phylogenetic relationships within the Phascolostrongylinae and its relationship with the families Chabertiidae and Strongylidae were inferred from aligned, concatenated amino acid sequence data sets. RESULTS: Within the Phascolostrongylinae, the wombat-specific genera grouped separately from the genera occurring in macropods. Two of the phascolostrongyline tribes were monophyletic, including Phascolostrongylinea and Hypodontinea, whereas the tribe Macropostrongyloidinea was paraphyletic. The tribe Phascolostrongylinea occurring in wombats was closely related to Oesophagostomum spp., also from the family Chabertiidae, which formed a sister relationship with the Phascolostrongylinae. CONCLUSION: The current phylogenetic relationship within the subfamily Phascolostrongylinae supports findings from a previous study based on ITS sequence data. This study contributes also to the understanding of the phylogenetic position of the subfamily Phascolostrongylinae within the Chabertiidae. Future studies investigating the relationships between the Phascolostrongylinae and Cloacininae from macropodid marsupials may advance our knowledge of the phylogeny of strongyloid nematodes in marsupials.

Redescription of Rugopharynx australis (Mönnig, 1926) and the description of R. moennigi n. sp. (Nematoda: Strongyloidea) from kangaroos (Marsupialia: Macropodidae) in Australia.

Rugopharynx australis (Mönnig, 1926) (Nematoda: Strongyloidea) is redescribed based on specimens from the type host, Osphranter rufus (Desmarest), together with matching DNA sequence data. Additional hosts were Macropus giganteus Shaw and Osphranter robustus (Gould) with single occurrences in M. fuliginosus (Desmarest), Notamacropus dorsalis (Gray), Lagorchestes conspicillatus Gould and Petrogale xanthopus Gray. Rugopharynx moennigi n. sp., formerly included within R. australis, is distinguished by shorter but overlapping spicule lengths and in the morphology of the gubernaculum as well as by molecular data. Rugopharynx moennigi n. sp. appears to be primarily parasitic in M. fuliginosus throughout its geographical range, but also infects M. giganteus, O. robustus and O. rufus in areas of host sympatry.

Effect of agitation speed on the density of bacteria Photorhabdus luminescens and the population dynamics of nematodes Heterorhabditis megidis in liquid culture.

Liquid culture is the most scalable technology for the industrial production of entomopathogenic nematodes. Variability of the recovery after inoculation into cultures of Photorhabdus luminescens remains a persistent problem in the mass production of Heterorhabditis sp. In order to enhance infective juvenile (IJ) recovery and improve nematode population management, we analysed the correlation between the nematode Heterorhabditis megidis (strain KV - 136) development in liquid cultures, the density of bacteria of P. luminescens and the culture agitation speed. Analyses focused on the impact of different agitation speeds (160 rpm and 200 rpm) on the dynamics of population growth of H. megidis in liquid cultures at constant biotic and abiotic parameters (initial dose of nematodes introduced to the culture 2300 IJs/ml, temperature 25°C, the number of bacterial colonies 0.3 × 107/ml). The performed experiments showed that the agitation speed of 200 rpm favourably affected the density of bacteria of P. luminescens (24.14 × 107/ml). High density of bacteria at this agitation speed resulted in an earlier (on the fifth day of the culture) maximum increase in the number of hermaphroditic individuals (1239.6 H/ml) than in the culture at an agitation speed of 160 rpm.

Climate Change Modulates Multitrophic Interactions Between Maize, A Root Herbivore, and Its Enemies.

How climate change will modify belowground tritrophic interactions is poorly understood, despite their importance for agricultural productivity. Here, we manipulated the three major abiotic factors associated with climate change (atmospheric CO2, temperature, and soil moisture) and investigated their individual and joint effects on the interaction between maize, the banded cucumber beetle (Diabrotica balteata), and the entomopathogenic nematode (EPN) Heterorhabditis bacteriophora. Changes in individual abiotic parameters had a strong influence on plant biomass, leaf wilting, sugar concentrations, protein levels, and benzoxazinoid contents. Yet, when combined to simulate a predicted climate scenario (Representative Concentration Pathway 8.5, RCP 8.5), their effects mostly counter-balanced each other. Only the sharp negative impact of drought on leaf wilting was not fully compensated. In both current and predicted scenarios, root damage resulted in increased leaf wilting, reduced root biomass, and reconfigured the plant sugar metabolism. Single climatic variables modulated the herbivore performance and survival in an additive manner, although slight interactions were also observed. Increased temperature and CO2 levels both enhanced the performance of the insect, but elevated temperature also decreased its survival. Elevated temperatures and CO2 further directly impeded the EPN infectivity potential, while lower moisture levels improved it through plant- and/or herbivore-mediated changes. In the RCP 8.5 scenario, temperature and CO2 showed interactive effects on EPN infectivity, which was overall decreased by 40%. We conclude that root pest problems may worsen with climate change due to increased herbivore performance and reduced top-down control by biological control agents.

GAPEWORM (SYNGAMUS SPP.) PREVALENCE IN WISCONSIN GREATER PRAIRIE CHICKENS (TYMPANUCHUS CUPIDO PINNATUS).

Under Wisconsin state law, the greater prairie chicken (GRPC; Tympanuchus cupido pinnatus) has been listed as a threatened species since 1976. In 2014-15, we conducted a pilot study to determine the prevalence and intensity of gapeworms (Syngamus spp.) in female Wisconsin GRPCs collected from 2 monitored populations. We captured 62 female GRPCs using walk-in-style traps for females and night lighting for juveniles ≥45 days of age. From these individuals, we collected 15 carcasses of radio-marked birds, most of whom died due to predation events. Through dissection, we identified gapeworm in 20% of examined carcasses and report an intensity ranging between 4 and 74 worms.