Search Results (27)

Sheep and goats are an important source of livelihood for smallholder farmers in sub-Saharan Africa (SSA). These livestock are almost entirely managed by resource-poor, smallholder farmers and pastoralists. Despite the large number of sheep and goats in SSA, their productivity is low, mainly due to diseases, poor feed, and inferior breeds. This review aims to summarize the most important diseases in small ruminants in SSA, with a focus on current treatment and control strategies. The following diseases were identified as the most significant constraints for small ruminant farmers: helminthoses, including gastrointestinal nematode infestation, lungworm infestation, fasciolosis, and cerebral coenurosis; viral diseases, such as peste des petits ruminants (PPR), sheep and goat pox, and contagious ecthyma (orf); bacterial diseases, including contagious caprine pleuropneumonia (CCPP), pneumonic pasteurellosis, and anthrax; as well as ectoparasite infestations. The diseases have significant economic implications due to mortality and production losses. Depending on the disease, they may also impact trade and export and hinder the introduction of new, more productive breeds. The ability to control diseases more efficiently is often limited due to financial constraints. In the case of infection with internal parasites, a lack of knowledge about the epidemiology of the disease, as well as the availability of appropriate anthelmintics and the development of resistance against commonly used anthelmintics, are often barriers. The control of viral diseases depends on the accessibility, quality, and handling of vaccines, whereas in bacterial diseases, increasing antibiotic resistance and inappropriate antimicrobial treatments pose challenges, as well as the availability of appropriate vaccines and their use. In the case of ectoparasitic infections, a strategic, regular, and appropriate antiparasitic treatment approach is often not achieved. Full article

The forest swamp ecosystem, as a special wetland ecosystem, is a key link in the material cycle and an important carbon sink in the carbon cycle. The global carbon cycle is of great significance, but the impact of forest swamp succession and soil depth on soil active organic matter and nematode community structure and diversity is unclear. This study used the “space instead of time” method to investigate the succession process of forest swamps from grasslands (WC) and shrubs (WG) to forests (WS) in national nature reserves. The results showed that during the forest succession process, the dominant nematode communities in the WC and WG stages were dominated by the genera Apis and Labroidei, while the dominant genera increased in the WS stage. The total abundance of nematodes increased, and the number of groups was ordered WG > WC > WS. The diversity in soil nematode communities according to Shannon–Wiener (H′), Pielou (J), and Trophic diversity (TD) was WS > WG > WC, which is related to vegetation, soil physical and chemical properties, and microbial community structure. The maturity index (MI) was WG > WS > WC. The soil food web was dominated by bacterial channels and had characteristics in forest metabolic activity and regulation ability. At different soil depths, there were significant differences in the community, with species such as the spiny cushioned blade genus being key. The number and group size of nematodes varied from 0–10 cm > 10–20 cm > 20–30 cm. The relative abundance of feeding nematodes changed with depth, while diversity indices such as H′, J, and TD decreased with depth. Ecological function indices such as MI and PPI showed depth variation patterns, while basic indices (BI) and channel indices (CI) showed significant differences. In terms of soil variables, during the forest succession stage, soil organic carbon (SOC), soluble organic nitrogen (DON), easily oxidizable organic carbon (ROC), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) showed a gradually increasing trend with WC-WG-WS, while total nitrogen (TN), soluble organic carbon (DOC), soil temperature (ST), and soil moisture (SM) showed opposite changes. There were significant differences in soil ST, SM, and DON values with succession (p < 0.05). At different soil depths, except for DON and ROC, which increased first and then decrease with depth, the values of other physical and chemical factors and active carbon and nitrogen components at depths of 0–10 cm were higher than those at other depths and decreased with depth. An analysis of variance showed significant differences in MBC and MBN values at different soil depths (p < 0.05), which is of great significance for a deeper understanding of the mechanism of soil nematode community construction and its relationship with the environment. Full article

The reclamation of post-mining land for agricultural purposes has continued to be a big challenge. Our study concerns the use of soil microfauna (nematodes) and mesofauna (mites and springtails) as indicators of soil quality after 6 years of agricultural reclamation of a post-mining area in west–central Poland. A new method, which involves rotation growing of industrial hemp (H) and alfalfa (A) and incorporating the resulting biomass into the soil, was used to reclaim two sites (5 and 15 years after mining) representing different types of post-mining deposits (clayey and sandy). On each site, two plots were established, where each crop was grown for three years, but in a different order during the rotation cycle (3H3A and 3A3H). The results showed significant differences in the abundance and structure of the fauna communities between 3H3A and 3A3H reclamation practices, as well as between the reclaimed plots and non-reclaimed (NR) plots, where spontaneous succession proceeded. The three animal groups were more abundant in the reclaimed soil compared to the NR soil. The highest densities for nematodes were observed in the 3H3A plots and for the mesofauna in the 3A3H plots. The reclamation practices had a positive effect on groups involved in the regulation of C and N mineralisation, particularly bacterial- and hyphal-feeding nematodes and oribatid mites, and a negative effect on plant-feeding nematodes and euedaphic collembolans. The finding that most of the parameters of the studied biota had values resembling those of agricultural soils after 6 years of reclamation clearly indicates the effectiveness of the applied practices for transforming degraded land into soils that mirror soils under agricultural use. Full article

Earthworms are soil macrofauna that control soil ecosystems by strongly influencing soil nematodes, microorganisms, and nutrient cycling, as well as soil environmental factors. We have discovered an earthworm cyclic peptide that disrupts nematode DNA, affecting its lifespan, reproduction, and feeding preferences. To investigate the effects of this peptide on soil, it was added to soil, and changes in soil nematode, bacterial and fungal communities, soil nutrient contents, and basal respiration were measured on days 5 and 21. The results showed that the peptide reduced soil basal respiration on day 5 and soil NO₃-N on day 21, decreased soil fungivores nematodes on day 5 and soil nematode abundance on day 21, and increased soil fungal community richness and diversity. It also altered the soil bacterial community structure between day 5 and the soil fungal community structure on days 5 and 21. The peptide regulates the soil environment by influencing the structure of soil bacterial and fungal communities through the soil nematode community, as demonstrated by partial least squares path modelling (PLS-PM) analyses. Earthworm cyclic peptides mediates tri-trophic interactions between earthworms, nematodes, microbes, and environmental factors, providing new insights into soil biota interactions and feedback in dynamic soil food webs. Full article

Vermicomposting stands as a sustainable and environmentally friendly waste management practice, leveraging the metabolic prowess of earthworms to facilitate the decomposition of organic matter into nutrient-rich compost. The aim of this experiment was to study the influence of Eisenia fetida on the density and the tropic structure of a nematode community during the vermicomposting process over a period of 3 months. Sewage sludge and green waste served as composting substrates. Overall, six compost variants were prepared consisting of three variants incorporating E. fetida and three control variants lacking E. fetida. Throughout the investigation, samples were gathered on a monthly basis, with each variant undergoing three repetitions. The aim was to isolate nematodes, determine the population density of the five trophic groups, and identify the dominant community. The anaysis was conducted employing both microscopic examination and molecular metabarcoding (NGS). It was shown that the bacterial-feeding community maintained dominance. The introduction of E. fetida into the compost led to a significant rise in the abundance of Diplogasteridae. In the variant without E. fetida, the amount of Diplodasteridae exceeded 0.1% only after the 30th (C3) or the 60th (C1, C2) day of composting, while in the compost with E. fetida, they were present in large amounts (ranging from 11.0% to 28.0%) already on the 30th day of composting. The introduction of Eisenia fetida also led to a notable reduction in H. gingivalis with significant implications for mitigating the risk of halicephalobiosis. The introduction of E. fetida resulted in reducing H. gingivalis to levels below 0.1% in all compost variants. Full article

Biodiversity within composting systems involves a variety of microorganisms including nematodes. In the research, nematode populations were monitored within six simultaneously operating composting processes. These processes involved varying proportions of feedstock materials. The primary objective was to evaluate the consistency of nematode community succession patterns across the composting processes over a time of 3 months. During the study, samples were taken every month to isolate nematodes, determine the population density of the five trophic groups (per genus) and determine the dominant nematode species. It was shown that the bacterial-feeding community maintained dominance, while the fungus-feeding nematodes gradually increased in dominance as the maturation process progressed. The presence of predatory nematodes Mononchoides which were initially absent, along with the total absence of parasitic nematodes in the late stages of waste stabilization, serves as strong evidence for the reliable evaluation of the biodegradable waste processing level. Based on the obtained results, it is evident that the succession of nematode communities holds promise as a reliable method for evaluating compost maturity. Full article

The role of the microbiota in health and disease is a research area receiving much attention in academia and industry. A person’s microbiota refers to a community of microorganisms found mainly in the gut. It is estimated that around 39 trillion bacteria can be found on and inside the human body and there is increasing evidence that they influence human health. Advances in sequencing techniques are revolutionizing characterization of the human microbiome. However, causality and underlying molecular mechanisms are still largely unknown due to the complexity of the human microbiome and its interaction with the host. Turning towards simpler host organisms and using well-defined microbiomes are two ways to strengthen studies of causality and mechanism. Here, we show that the nematode Caenorhabditis elegans can be used as host to study sub-microbiomes derived from human feces samples prepared for fecal microbiota transplantation following a simple feeding protocol. Approximately 200 amplicon sequence variants were identified in the worm gut following transplantation with human fecal microbiota samples. We find that the gut microbiome does not simply reflect the bacterial community initially fed to the worms. Hence, our experimental setup can be used to identify and characterize host genetic factors shaping the microbiota and improving our understanding of host–human microbiome interactions. Full article

Soil food webs are extremely complex as they contain diverse organisms. Feeding preference, also known as prey selection, is an important determinant of soil community compositions. However, the feeding preferences of nematodes are commonly ignored in ecology research. In this paper, the population dynamics and feeding preferences of three bacterial-feeding nematodes (i.e., Caenorhabditis elegans, Protorhabditis spp., and Acrobeloides spp.) for eight bacterial prey species were evaluated. Protorhabditis and Acrobeloides were isolated from a paddy soil in subtropical China. C. elegans, the most common model system for biological research, was used as a control in this study, and it was revealed that C. elegans could feed on all the eight bacteria strains. Protorhabditis could only survive when fed E. coli and Bacillus thuringiensis. Acrobeloides could only survive when fed E. coli and B. aryabhattai. During 10 days of culture, C. elegans populations reached the maximum in 5–7 days, and most C. elegans populations exceeded 10,000 individuals. The two Protorhabditis populations on E. coli and Bacillus thuringiensis included less than 800 individuals during 10 days of culture. Acrobeloides population on B. aryabhattai reached the maximum (7799 individuals) on day 8, while on E. coli was its population included less than 500 individuals. These results indicate that different nematode species indeed have distinct feeding preferences. In addition, the population dynamics of the two soil nematodes isolated from soil could not fully match with their inferred life-history strategies (i.e., cp values, and a 1-5 colonizer-p-ersister series that range from r-strategists to K-strategists). Our findings highlights the existing deficiencies in the understanding of the feeding behavior and the life-history strategies of soil nematodes. Full article

Free-living nematodes harbor and disseminate various soil-borne bacterial pathogens. Whether they function as vectors or environmental reservoirs for the aquatic L. pneumophila, the causative agent of Legionnaires’ disease, is unknown. A survey screening of biofilms of natural (swimming lakes) and technical (cooling towers) water habitats in Germany revealed that nematodes can act as potential reservoirs, vectors or grazers of L. pneumophila in cooling towers. Consequently, the nematode species Plectus similis and L. pneumophila were isolated from the same cooling tower biofilm and taken into a monoxenic culture. Using pharyngeal pumping assays, potential feeding relationships between P. similis and different L. pneumophila strains and mutants were examined and compared with Plectus sp., a species isolated from a L. pneumophila-positive thermal source biofilm. The assays showed that bacterial suspensions and supernatants of the L. pneumophila cooling tower isolate KV02 decreased pumping rate and feeding activity in nematodes. However, assays investigating the hypothesized negative impact of Legionella’s major secretory protein ProA on pumping rate revealed opposite effects on nematodes, which points to a species-specific response to ProA. To extend the food chain by a further trophic level, Acanthamoebae castellanii infected with L. pneumphila KV02 were offered to nematodes. The pumping rates of P. similis increased when fed with L. pneumophila-infected A. castellanii, while Plectus sp. pumping rates were similar when fed either infected or non-infected A. castellanii. This study revealed that cooling towers are the main water bodies where L. pneumophila and free-living nematodes coexist and is the first step in elucidating the trophic links between coexisting taxa from that habitat. Investigating the Legionella–nematode–amoebae interactions underlined the importance of amoebae as reservoirs and transmission vehicles of the pathogen for nematode predators. Full article

Pine wilt disease (PWD) has caused extensive mortality in pine forests worldwide. The longicorn beetle Monochamus saltuarius, as the vector of the invasive species Bursaphelenchus xylophilus, plays an important role in the infection cycle. Although the gut microbiota and its contribution to health and disease have been extensively documented, it is unclear whether B. xylophilus affects the longicorn gut microbiota because of a lack of understanding of potential temporal changes in the microbial composition of the vector beetles. In this study, we collected beetles at the emergence and mating stages, and divided them into two groups according to whether they carried nematodes. Based on 16S rDNA sequence analysis, 174 bacterial species were identified that belonged to 112 genera, 53 families, and 8 phyla. Bursaphelenchus xylophilus increased the microflora abundance and diversity of the infected M. saltuarius. In addition, Firmicutes and Bacteroidetes were more abundant in infected M. saltuarius at the same developmental stage. Some of the bacteria in these two phyla were the key species in the co-occurrence network of intestinal flora and represented a unique module in the co-occurrence network of infected M. saltuarius. We found some high abundance colonies in the intestinal tract of infected M. saltuarius during the emergence period that were mostly related to metabolism. Compared with the emergence period, there were more similar microorganisms in the intestinal tract of M. saltuarius during the mating period. With the change in growth environment and continuous feeding, the intestinal microorganisms gradually stabilized and became single species. Full article

A rich source of bioactive secondary metabolites from microorgannisms are widely used to control plant diseases in an eco-friendly way. To explore ideal candidates for prevention of pine wilt disease (PWD), a bacterial strain from rhizosphere of Pinus thunbergii, Lysinimonas M4, with nematicidal activity against pine wood nematode (PWN), Bursaphelenchus xylophilus, was isolated. Two nematicidal compounds were obtained from the culture of Lysinimonas M4 by silica gel chromatography based on bioactivity-guided fractionation and were subsequently identified as 2-coumaranone and cyclo-(Phe-Pro) by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The 2-coumaranone and cyclo-(Phe-Pro) showed significant nematicidal activity against PWN, with LC₅₀ values at 24 h of 0.196 mM and 0.425 mM, respectively. Both compounds had significant inhibitory effects on egg hatching, feeding, and reproduction. The study on nematicidal mechanisms revealed that 2-coumaranone and cyclo-(Phe-Pro) caused the accumulation of reactive oxygen species (ROS) in nematodes, along with a notable decrease in CAT and POS activity and an increase in SOD activity in nematodes, which might contribute to the death of pine wood nematodes. Bioassay tests demonstrated that the two compounds could reduce the incidence of wilting in Japanese black pine seedlings. This research offers a new bacterial strain and two metabolites for biocontrol against PWN. Full article

Plasmids are mostly found in bacteria as extrachromosomal genetic elements and are widely used in genetic engineering. Exploring the mechanisms of plasmid–host interaction can provide crucial information for the application of plasmids in genetic engineering. However, many studies have generally focused on the influence of plasmids on their bacterial hosts, and the effects of plasmids on bacteria-feeding animals have not been explored in detail. Here, we use a “plasmid–bacteria–Caenorhabditis elegans” model to explore the impact of plasmids on their host bacteria and bacterivorous nematodes. First, the phenotypic responses of C. elegans were observed by feeding Escherichia coli OP50 harboring different types of plasmids. We found that E. coli OP50 harboring plasmid pEX18Gm unexpectedly increases the fecundity of C. elegans. Subsequently, we found that the plasmid pEX18Gm indirectly affects C. elegans fecundity via bacterial metabolism. To explore the underlying regulatory mechanism, we performed bacterial RNA sequencing and performed in-depth analysis. We demonstrated that the plasmid pEX18Gm upregulates the transcription of methionine synthase gene metH in the bacteria, which results in an increase in methionine that supports C. elegans fecundity. Additionally, we found that a pEX18Gm-induced increase in C. elegans can occur in different bacterial species. Our findings highlight the plasmid–bacteria–C. elegans model to reveal the mechanism of plasmids’ effects on their host and provide a new pattern for systematically studying the interaction between plasmids and multi-species. Full article

Diets regulate animal development, reproduction, and lifespan. However, the underlying molecular mechanisms remain elusive. We previously showed that a chemically defined CeMM diet attenuates the development and promotes the longevity of C. elegans, but whether it impacts other nematodes is unknown. Here, we studied the effects of the CeMM diet on the development and longevity of the marine nematode Litoditis marina, which belongs to the same family as C. elegans. We further investigated genome-wide transcriptional responses to the CeMM and OP50 diets for both nematodes, respectively. We observed that the CeMM diet attenuated L. marina development but did not extend its lifespan. Through KEEG enrichment analysis, we found that many of the FOXO DAF-16 signaling and lysosome and xenobiotic metabolism related genes were significantly increased in C. elegans on the CeMM diet, which might contribute to the lifespan extension of C. elegans. Notably, we found that the expression of lysosome and xenobiotic metabolism pathway genes was significantly down-regulated in L. marina on CeMM, which might explain why the CeMM diet could not promote the lifespan of L. marina compared to bacterial feeding. Additionally, the down-regulation of several RNA transcription and protein generation and related processes genes in C. elegans on CeMM might not only be involved in extending longevity, but also contribute to attenuating the development of C. elegans on the CeMM diet, while the down-regulation of unsaturated fatty acids synthesis genes in L. marina might contribute to slow down its growth while on CeMM. This study provided important insights into how different diets regulate development and lifespan, and further genetic analysis of the candidate gene(s) of development and longevity will facilitate exploring the molecular mechanisms underlying how diets regulate animal physiology and health in the context of variable nutritional environments. Full article

Root-feeding Amphimallon solstitiale larvae and certain other scarab beetles are the main soil-dwelling pests found in Europe, while entomopathogenic nematodes (EPN) have been used as a biocontrol agent against these species. Our study provides the first detailed characterization of the bacterial community of the midgut in wild A. solstitiale larvae, based on the nanopore sequencing of the 16S rRNA gene. In the whole dataset, we detected 2586 different genera and 11,641 species, with only 83 diverse bacterial genera shared by all studied individuals, which may represent members of the core midgut microbiota of A. solstitiale larvae. Subsequently, we compared the midgut microbiota of EPN-resistant and T0 (prior to EPN exposure) individuals, hypothesizing that resistance to this parasitic infection may be linked to the altered gut community. Compared to the control, the resistant insect microbiota demonstrated lower Shannon and Evenness indices and significant differences in the community structure. Our studies confirmed that the gut microbiota alternation is associated with resistant insects; however, there are many processes involved that can affect the bacterial community. Further research on the role of gut microbiota in insect-parasitic nematode interaction may ultimately lead to the improvement of biological control strategies in insect pest management. Full article

Composting is an effective strategy to process agricultural and urban waste into forms that may be beneficial to crops. The objectives of this orchard field study were to characterize how a dairy manure compost and a food waste compost influenced: (1) soil nitrogen and carbon pools, (2) bacterial and nematode soil food webs and (3) tree growth and leaf N. The effects of composts were compared with fertilized and unfertilized control plots over two years in a newly planted almond orchard. Both dairy manure compost and food waste compost increased soil organic matter pools, as well as soil nitrate and ammonium at certain time points. Both composts also distinctly altered bacterial communities after application, specifically those groups with carbon degrading potential, and increased populations of bacterial feeding nematodes, although in different timeframes. Unique correlations were observed between nematode and bacterial groups within compost treatments that were not present in controls. Food waste compost increased trunk diameters compared to controls and had greater relative abundance of herbivorous root tip feeding nematodes. Results suggest that recycled waste composts contribute to biologically based nitrogen cycling and can increase tree growth, mainly within the first year after application. Full article