Interaction between bacterial microbiota and nematode parasite communities in sheep's gastrointestinal tract.

The economic impact of gastrointestinal (GI) nematode infections on livestock production is well documented worldwide. Increasing evidence supports the hypothesis that parasite colonization induces significant changes in the GI tract environment and, therefore, in the landscape where the microbiota and parasites occur. Understanding the interactions between bacterial and parasite populations in the digestive tract of livestock may be useful to design parasite control strategies based on microbiota modification. The aims of this work were to investigate the impact of the oxytetracycline-mediated manipulation of the gut microbial community on the composition of GI nematode populations in naturally infected sheep and to explore changes in the GI microbial communities after nematode population treatment with the anthelmintic compound monepantel. Extensive manipulation of the GI microbiota with a therapeutic dose of the long-acting oxytetracycline formulation did not induce significant changes in the GI nematode burden. The gut microbiota of treated animals returned to control levels 17 days after treatment, suggesting strong resilience of the sheep microbial community to antibiotic-mediated microbiota perturbation. A significant decrease of the bacterial Mycoplasmataceae family (Log2FC = -4, Padj = 0.001) and a marked increase of the Methanobacteriaceae family (Log2FC = 2.9, Padj = 0.018) were observed in the abomasum of sheep receiving the monepantel treatment. While a comprehensive evaluation of the interactions among GI mycoplasma, methanobacteria and nematode populations deserves further assessment, the bacteria-nematode population interactions should be included in future control programs in livestock production. Understanding how bacteria and parasites may influence each other in the GI tract environment may substantially contribute to the knowledge of the role of microbiota composition in nematode parasite establishment and the role of the parasites in the microbiota composition.

Characterization of the Hepatic Transcriptome for Divergent Immune-Responding Sheep Following Natural Exposure to Gastrointestinal Nematodes.

Infections with gastrointestinal nematodes (GINs) reduce the economic efficiency of sheep operations and compromise animal welfare. Understanding the host's response to GIN infection can help producers identify animals that are naturally resistant to infection. The objective of this study was to characterize the hepatic transcriptome of sheep that had been naturally exposed to GIN parasites. The hepatic transcriptome was studied using RNA-Sequencing technology in animals characterized as high (n = 5) or medium (n = 6) based on their innate immune acute-phase (AP) response phenotype compared with uninfected controls (n = 4), and with biased antibody-mediated (AbMR, n = 5) or cell-mediated (CMR, n = 5) adaptive immune responsiveness compared to uninfected controls (n = 3). Following the assessment of sheep selected for innate responses, 0, 136, and 167 genes were differentially expressed (DE) between high- and medium-responding animals, high-responding and uninfected control animals, and medium-responding and uninfected control animals, respectively (false discovery rate (FDR) < 0.05, and fold change |FC| > 2). When adaptive immune responses were assessed, 0, 53, and 57 genes were DE between antibody- and cell-biased animals, antibody-biased and uninfected control animals, and cell-biased and uninfected control animals, respectively (FDR < 0.05, |FC| > 2). Functional analyses identified enriched gene ontology (GO) terms and metabolic pathways related to the innate immune response and energy metabolism. Six functional candidate genes were identified for further functional and validation studies to better understand the underlying biological mechanisms of host responses to GINs. These, in turn, can potentially help improve decision making and management practices to increase the overall host immune response to GIN infection.

First evaluation and detection of ivermectin resistance in gastrointestinal nematodes of sheep and goats in South Darfur, Sudan.

In Sudan, resistance to benzimidazoles has been reported recently in cattle and goats from South Darfur. Herein, ivermectin efficacy against gastrointestinal nematodes (GINs) was evaluated in sheep and goats in three study areas in South Darfur. The faecal egg count reduction test (FECRT) was used to evaluate the efficacy of ivermectin in sheep and goats naturally infected with GINs in the region of Bulbul (goats: n = 106), Kass (goats: n = 40) and Nyala (Domaia (sheep: n = 47, goats: n = 77) and the University farm (goats: n = 52)), using different treatment plans, and the efficacy was evaluated 12 days after treatment. Ivermectin efficacy was also evaluated in goats experimentally infected using local Haemonchus contortus isolates from Kass and Nyala. Nematodes surviving ivermectin treatment in goats in Bulbul and Nyala were harvested and larvae used to infect worm-free male sheep (n = 6, ≤6 months old). Infected sheep were dosed subcutaneously with ivermectin every eight days with increasing doses from 0.2 mg/kg to 1.6 mg/kg bodyweight (bw). Reduced ivermectin efficacy was identified in sheep and goats in the four study locations. Using a paired statistic, the efficacy of a therapeutic dose in sheep was 75.6% (90% upper credible limit (UCrL): 77.5%), while twice the recommended dose led to a reduction of 92.6% (90% UCrL: 93.3%). In goats, the FECRs of a therapeutic dose were 72.9-95.3% (90% UCrL range: 73.6-95.7%) in Bulbul, Nyala Domaia, Nyala University farm and Kass. Twice the dose recommended for goats in Bulbul revealed a 90% UCrL of 87.6%. All post-treatment faecal cultures contained only Haemonchus spp. larvae. The experimental infection trials in sheep and goats supported our findings from field trials and calculated upper 90% CrL of below 98.9%. For the first time highly ivermectin resistant H. contortus populations have been identified in sheep and goats in Sudan, and resistance was experimentally confirmed.

Epidemiology and diversity of gastrointestinal tract helminths of wild ruminants in sub-Saharan Africa: a review.

This review summarises studies on distribution, diversity, and prevalence of gastrointestinal helminth infections in wild ruminants in sub-Saharan Africa. The results showed that 109 gastrointestinal tract (GIT) helminth species or species complexes were recorded in 10 sub-Saharan African countries. South Africa reported the highest number of species because most studies were carried out in this country. Eighty-eight nematode species or species complexes were recorded from 30 wild ruminant species across eight countries. The genus Trichostrongylus recorded the highest number of species and utilised the highest number of wild ruminant species, and along with Haemonchus spp., was the most widely distributed geographically. Fifteen trematode species or species complexes were reported from seven countries. The genus Paramphistomum recorded the highest number of species, and Calicophoron calicophoron was the most commonly occurring species in sub-Saharan African countries and infected the highest number of hosts. Six cestode species or species complexes from one family were documented from 14 wild hosts in seven countries. Moniezia spp. were the most commonly distributed in terms of host range and geographically. Impala were infected by the highest number of nematodes, whilst Nyala were infected by the highest number of trematode species. Greater kudu and Impala harbored the largest number of cestodes. The prevalence amongst the three GIT helminths taxa ranged between 1.4% and 100% for nematodes, 0.8% and 100% for trematodes, and 1.4% and 50% for cestodes. There is still limited information on the distribution and diversity of GIT helminths in wild ruminants in most sub-Saharan African countries.

Urea regulates soil nematode population by enhancing the nematode-trapping ability of nematode-trapping fungi.

As the most abundant animal in the soil, nematodes are directly or indirectly involved in almost all soil ecological processes. Studying soil nematode population regulation is essential to understanding soil ecological processes. This study found urea combines nematode-trapping fungi to regulate the population of soil nematodes. In soil, compared with no urea, adding 0.2 mg/mL urea after applying Arthrobotrys oligospora and Dactylellina ellipsospora reduced the number of nematodes by 34.7% and 31.7%. Further, the mechanism of urea couple nematode-trapping fungi to regulate the nematode population was explored in the medium environment. The results showed that the addition of 0.2 mg/ml urea accelerated the trap formation of A. oligospora and D. ellipsosporas by 50% and 46.5%, and increased the yield of traps of A. oligospora and D. ellipsosporas by 39.5% and 40.6%, thus, the predatory efficiency of A. oligospora and D. ellipsospora on nematodes was increased by 34.2% and 32.7%. In conclusion, urea regulates the predation ability of A. oligospora and D. ellipsosporas to regulate the soil nematode population. This study deepens the understanding of the regulatory pathways of the soil nematodes but also provides a potential new strategy for harmful nematode bio-control.

Comparative mitochondrial genomics in Nematoda reveal astonishing variation in compositional biases and substitution rates indicative of multi-level selection.

BACKGROUND: Nematodes are the most abundant and diverse metazoans on Earth, and are known to significantly affect ecosystem functioning. A better understanding of their biology and ecology, including potential adaptations to diverse habitats and lifestyles, is key to understanding their response to global change scenarios. Mitochondrial genomes offer high species level characterization, low cost of sequencing, and an ease of data handling that can provide insights into nematode evolutionary pressures. RESULTS: Generally, nematode mitochondrial genomes exhibited similar structural characteristics (e.g., gene size and GC content), but displayed remarkable variability around these general patterns. Compositional strand biases showed strong codon position specific G skews and relationships with nematode life traits (especially parasitic feeding habits) equal to or greater than with predicted phylogeny. On average, nematode mitochondrial genomes showed low non-synonymous substitution rates, but also high clade specific deviations from these means. Despite the presence of significant mutational saturation, non-synonymous (dN) and synonymous (dS) substitution rates could still be significantly explained by feeding habit and/or habitat. Low ratios of dN:dS rates, particularly associated with the parasitic lifestyles, suggested the presence of strong purifying selection. CONCLUSIONS: Nematode mitochondrial genomes demonstrated a capacity to accumulate diversity in composition, structure, and content while still maintaining functional genes. Moreover, they demonstrated a capacity for rapid evolutionary change pointing to a potential interaction between multi-level selection pressures and rapid evolution. In conclusion, this study helps establish a background for our understanding of the potential evolutionary pressures shaping nematode mitochondrial genomes, while outlining likely routes of future inquiry.

Morphological and molecular data on acuariid nematodes in European great cormorants (Phalacrocorax carbo sinensis) and pygmy cormorants (Microcarbo pygmaeus).

The family Acuariidae is a speciose group of parasitic nematodes, infecting mostly birds as definitive hosts. This study focused on the characterization of two species of acuariids, collected in two different species of piscivorous birds, the European great cormorant Phalacrocorax carbo sinensis from Italy, and the pygmy cormorant Microcarbo pygmaeus from Israel. Parasites were analyzed using light and scanning electron microscopy and by amplification and sequencing of the 28S rDNA. The results of morphological and molecular analyses showed that Ph. carbo sinensis was infected by the acuariid Syncuaria squamata (12 females) and Cosmocephalus obvelatus (1 female), whereas M. pygmaeus was infected by C. obvelatus (2 males, 12 females). The present results provide new data on the distribution of acuariid parasites of piscivorous birds, the first report of Acuariidae in Israel, and the first molecular data on S. squamata and C. obvelatus, which will be useful in future epidemiological and phylogenetic studies of these widely distributed, but less molecularly studied parasites.

Microbiota succession influences nematode physiology in a beetle microcosm ecosystem.

Unravelling the multifaceted and bidirectional interactions between microbiota and host physiology represents a major scientific challenge. Here, we utilise the nematode model, Pristionchus pacificus, coupled to a laboratory-simulated decay process of its insect host, to mimic natural microbiota succession and investigate associated tripartite interactions. Metagenomics reveal that during initial decay stages, the population of vitamin B-producing bacteria diminishes, potentially due to a preferential selection by nematodes. As decay progresses to nutrient-depleted stages, bacteria with smaller genomes producing less nutrients become more prevalent. Lipid utilisation and dauer formation, representing key nematode survival strategies, are influenced by microbiota changes. Additionally, horizontally acquired cellulases extend the nematodes' reproductive phase due to more efficient foraging. Lastly, the expressions of Pristionchus species-specific genes are more responsive to natural microbiota compared to conserved genes, suggesting their importance in the organisms' adaptation to its ecological niche. In summary, we show the importance of microbial successions and their reciprocal interaction with nematodes for insect decay in semi-artificial ecosystems.

Cucullanus lithodorasi n. sp. (Nematoda: Cucullanidae), a parasite of Lithodoras dorsalis (Siluriformes: Doradidae) on the north coast of Brazil.

Cucullanus lithodorasi n. sp. (Nematoda: Cucullanidae), collected from the intestine of Lithodoras dorsalis (Siluriformes) and waters of the north coast of Brazil is described based on light and scanning electron microscopic observations. The new species differs from its congeners in the number and arrangement of cloacal papillae: five precloacal pairs and five postcloacal pairs and presence of unpaired ventral papillae located slightly anterior to the cloaca. This is the third nominal species of the genus infecting fishes from brackish water from Brazil.

Evaluation of the efficacy of entomopathogenic nematodes on Ctenocephalides felis felis larvae (Siphonaptera: Pulicidae).

Ctenocephalides felis felis is a relevant and widely distributed ectoparasite that acts as a vector of disease-causing pathogens. Moreover, it is responsible for economic losses due the use of harmful chemicals to the environment and that favor the emergence of insecticide-resistant populations. Research on entomopathogenic nematodes may open up an alternative route to the insect chemical control. The present study aimed to evaluate the killing efficacy of Heterorhabditis bacteriophora (HP88) against C. felis larvae in 400 µL, 600 µL and 1000 µL of suspension containing 120, 160 and 200 infective juveniles/larva and 600 µL of suspension containing the same concentrations of Heterorhabditis indica (LPP30), divided into two groups (absence and presence of diet) and a control group with three replications containing only distilled water. In the bioassay with H. bacteriophora, the groups in 600 µL of suspension showed higher mortality rates than those in the other tested volumes, which were above 80% at all concentrations. On the other hand, H. indica achieved mortality rates above 70% at all concentrations used. Results indicate that flea larvae are susceptible to in vitro infection by H. bacteriophora and H. indica.

Human parasitic infections of the class Adenophorea: global epidemiology, pathogenesis, prevention and control.

BACKGROUND: Human parasitic infections caused by Adenophorean nematodes encompass a range of diseases, including dioctophymiasis, trichuriasis, capillariasis, trichinellosis, and myositis. These infection can result in adverse impacts on human health and cause societal and economic concerns in tropical and subtropical regions. METHODS: This review conducted searches in PubMed, Embase and Google Scholar for relevant studies that published in established databases up to April 26, 2024. Studies that focused on the common morphology, life cycle, disease distribution, clinical manifestations, and prevention and control strategies for Adenophorean parasitic diseases in humans were included. RESULTS: Adenophorean nematodes exhibit shared morphological characteristics with a four-layered cuticle; uninucleate epidermal cells; pseudocoelom with six or more coelomocytes; generally three caudal glands; five esophageal glands; two testes in males with median-ventral supplementary glands in a single row; tail in males rarely possessing caudal alae; amphids always postlabial; presence of cephalic sensory organs; absence of phasmids; and a secretory-excretory system consisting of a single ventral gland cell, usually with a non-cuticularized terminal duct. Humans play two important roles in the life cycle of the nematode class, Adenophorea: 1) as a definitive host infected by ingesting undercooked paratenic hosts, embryonated eggs, infective larvae in fish tissue and meat contaminated with encysted or non-encysted larvae, and 2) as an accidental host infected by ingesting parasitic eggs in undercooked meat. Many organs are targeted by the Adenophorean nematode in humans such as the intestines, lungs, liver, kidneys, lymphatic circulation and blood vessels, resulting in gastrointestinal problems, excessive immunological responses, cell disruption, and even death. Most of these infections have significant incidence rates in the developing countries of Africa, Asia and Latin America; however, some parasitic diseases have restricted dissemination in outbreaks. To prevent these diseases, interventions together with education, sanitation, hygiene and animal control measures have been introduced in order to reduce and control parasite populations. CONCLUSIONS: The common morphology, life cycle, global epidemiology and pathology of human Adenophorean nematode-borne parasitic diseases were highlighted, as well as their prevention and control. The findings of this review will contribute to improvement of monitoring and predicting human-parasitic infections, understanding the relationship between animals, humans and parasites, and preventing and controlling parasitic diseases.

Bacterial communities associated with Acrobeles complexus nematodes recovered from tomato crops in South Africa.

The productivity of agricultural ecosystems is heavily influenced by soil-dwelling organisms. To optimize agricultural practices and management, it is critical to know the composition, abundance, and interactions of soil microorganisms. Our study focused on Acrobeles complexus nematodes collected from tomato fields in South Africa and analyzed their associated bacterial communities utilizing metabarcoding analysis. Our findings revealed that A. complexus forms associations with a wide range of bacterial species. Among the most abundant species identified, we found Dechloromonas sp., a bacterial species commonly found in aquatic sediments, Acidovorax temperans, a bacterial species commonly found in activated sludge, and Lactobacillus ruminis, a commensal motile lactic acid bacterium that inhabits the intestinal tracts of humans and animals. Through principal component analysis (PCA), we found that the abundance of A. complexus in the soil is negatively correlated with clay content (r = -0.990) and soil phosphate levels (r = -0.969) and positively correlated with soil sand content (r = 0.763). This study sheds light on the bacterial species associated to free-living nematodes in tomato crops in South Africa and highlights the occurrence of various potentially damaging and beneficial nematode-associated bacteria, which can in turn, impact soil health and tomato production.

Grass-Endophyte Interactions and Their Associated Alkaloids as a Potential Management Strategy for Plant Parasitic Nematodes.

Claviceptaceous endophytic fungi in the genus Epichloë mostly form a symbiotic relationship with cool-season grasses. Epichloë spp. are capable of producing bioactive alkaloids such as peramines, lolines, ergot alkaloids, and indole-diterpenes, which protect the host plant from herbivory by animals, insects, and nematodes. The host also benefits from enhanced tolerance to abiotic stresses, such as salt, drought, waterlogging, cold, heavy metals, and low nitrogen stress. The bioactive alkaloids produced can have both direct and indirect effects towards plant parasitic nematodes. Direct interaction with nematodes' motile stages can cause paralysis (nematostatic effect) or death (nematicidal effect). Indirectly, the metabolites may induce host immunity which inhibits feeding and subsequent nematode development. This review highlights the different mechanisms through which this interaction and the metabolites produced have been explored in the suppression of plant parasitic nematodes and also how the specific interactions between different grass genotypes and endophyte strains result in variable suppression of different nematode species. An understanding of the different grass-endophyte interactions and their successes and failures in suppressing various nematode species is essential to enable the proper selection of grass-endophyte combinations to identify the alkaloids produced, concentrations required, and determine which nematodes are sensitive to which specific alkaloids.

Advances in Migratory Plant Endoparasitic Nematode Effectors.

Unlike sedentary plant-parasitic nematodes, migratory plant endoparasitic nematodes (MPENs) are unable to establish permanent feeding sites, and all developmental stages (except eggs) can invade and feed on plant tissues and can be easily overlooked because of the unspecific symptoms. They cause numerous economic losses in agriculture, forestry, and horticulture. In order to understand the pathogenetic mechanism of MPENs, here we describe research on functions and host targets focused on currently identified effectors from six MPENs, namely Radopholus similis, Pratylenchus spp., Ditylenchus destructor, Bursaphelenchus xylophilus, Aphelenchoides besseyi, and Hirschmanniella oryzae. This information will provide valuable insights into understanding MPEN effectors and for future fostering advancements in plant protection.

Comparative Genomics of Sex, Chromosomes, and Sex Chromosomes in Caenorhabditis elegans and Other Nematodes.

The nematode phylum has evolved a remarkable diversity of reproductive modes, including the repeated emergence of asexuality and hermaphroditism across divergent clades. The species-richness and small genome size of nematodes make them ideal systems for investigating the genome-wide causes and consequences of such major transitions. The availability of functional annotations for most Caenorhabditis elegans genes further allows the linking of patterns of gene content evolution with biological processes. Such gene-centric studies were recently complemented by investigations of chromosome evolution that made use of the first chromosome-scale genome assemblies outside the Caenorhabditis genus. This review highlights recent comparative genomic studies of reproductive mode evolution addressing the hybrid origin of asexuality and the parallel gene loss following the emergence of hermaphroditism. It further summarizes ongoing efforts to characterize ancient linkage blocks called Nigon elements, which form central units of chromosome evolution. Fusions between Nigon elements have been demonstrated to impact recombination and speciation. Finally, multiple recent fusions between autosomal and the sex-linked Nigon element reveal insights into the dynamic evolution of sex chromosomes across various timescales.

Experimental study of organic enrichment on meiofaunal diversity.

The organic enrichment effects on the meiofauna and nematofauna were assessed for field sediment and other experimental ones enriched with organic matters conducted in the laboratory for 4 weeks. Also, dissolved oxygen (DO) and pH were monitored for each one. The abundance and diversity of meiofaunal groups and nematofauna varied. Strong significant correlations were found between DO and the studied items. Nematoda was the most abundant group in the field sediment and other experimental ones; their counts increased with the increase in organic enrichments and were dominated by deposit feeders. Amphipoda, Ostracoda and predator/omnivore nematodes disappeared in highly organic-enriched sediments. Changes in DO and organic enrichments might be the more attributable reasons for the alteration of the meiobenthic assemblages. The generic compositions of Nematoda provide a good indicator for environmental alterations.

A single subcutaneous dose of eprinomectin (Eprecis®) is effective against common gastrointestinal nematodes and lungworms in experimentally infected lactating goats.

BACKGROUND: The health and productivity of dairy goats continue to be impacted by gastrointestinal nematodes (GIN) and lungworms (LW). Eprinomectin (EPN) is frequently selected for treatment because it is generally effective and does not require a milk withdrawal period. However, some factors, such as lactation, can have an impact on EPN pharmacokinetics and potentially its efficacy. To evaluate whether this can alter the efficacy of Eprecis® 2%, an eprinomectin injectable solution, a study was performed in lactating goats using the dose currently registered in cattle, sheep and goats (0.2 mg/kg). METHODS: This study was a blinded, randomized, controlled trial performed according to the VICH guidelines. Eighteen (18) worm-free lactating goats were included and experimentally challenged on day 28 with a mixed culture of infective gastrointestinal and lung nematode larvae (Haemonchus contortus, Trichostrongylus colubriformis, Teladorsagia circumcincta, Dictyocaulus filaria). At D-1, fecal samples were collected to confirm patent infection in all animals. On D0, the goats were randomly allocated into two groups of nine goats; group 1 was treated with Eprecis® 2% at 0.2 mg/kg BW by subcutaneous injection, while group 2 remained untreated. Fecal samples for egg counts were collected from all animals on days 3, 5, 7, 9, 11 and 14. On D14, all goats were killed, and the abomasum, small intestine and lungs were removed, processed and subsampled to record the number and species of worms. RESULTS: The treatment was well tolerated. After treatment, the arithmetic mean FEC decreased in the treated group and remained < 5 EPG until the end of the study, while the arithmetic mean FEC in the control group remained > 849.0 EPG. At D14, goats in the treated group had very limited or zero total worm counts, whereas all animals from the control group had a high worm burden. The measured efficacy was 100.0% against H. contortus and T. colubriformis, 99.9% against T. circumcincta and 98.0% against D. filaria. CONCLUSIONS: Eprinomectin (Eprecis®, 20 mg/ml), administered at the label dose (0.2 mg/kg), is highly effective against gastrointestinal nematodes and lungworms in lactating goats.

Data on four species of Longidorus Micoletzky, 1922 (Nematoda: Longidoridae) from southern and southeastern Iran, including description of a new species.

Four species of the genus Longidorus were recovered from southern (Bushehr province) and southeastern (Southern Khorasan province) Iran. The first species, L. paratabrizicus n. sp. represents a new member to the genus and is characterised by 4.8-5.6 mm long females with anteriorly flattened lip region separated from the rest of the body by depression, amphidial fovea pocket-shaped without lobes, tail conical, dorsally convex, ventrally almost straight with bluntly rounded tip and males in population. By having similar lip region and tail shape, the new species most closely resembles five species viz. L. artemisiae, L. globulicauda, L. patuxentensis, L. sturhani, and L. tabrizicus. It represents the cryptic form of the last species. The second species belongs to L. mirus, recovered in both southern and southeastern Iran, representing the first record of the species after its original description. As an update to the characteristics of this species, it's all juvenile developmental stages were recovered and described. The criteria to separate L. mirus from two closely related species, L. auratus and L. africanus, are discussed. The third species belongs to L. persicus, a new record in southern Iran. The fourth species, L. orientalis was recovered in high population density in association with date palm trees in Bushehr province. The phylogenetic relationships of the new species and recovered populations of L. mirus and L. persicus were reconstructed using two ribosomal markers and the resulted topologies were discussed.

Biomass-Based, Dual Enzyme-Responsive Nanopesticides: Eco-friendly and Efficient Control of Pine Wood Nematode Disease.

Pine wood nematode (PWN) disease is a globally devastating forest disease caused by infestation with PWN, Bursaphelenchus xylophilus, which mainly occurs through the vector insect Japanese pine sawyer (JPS), Monochamus alternatus. PWN disease is notoriously difficult to manage effectively and is known as the "cancer of pine trees." In this study, dual enzyme-responsive nanopesticides (AVM@EC@Pectin) were prepared using nanocoating avermectin (AVM) after modification with natural polymers. The proposed treatment can respond to the cell wall-degrading enzymes secreted by PWNs and vector insects during pine tree infestation to intelligently release pesticides to cut off the transmission and infestation pathways and realize the integrated control of PWN disease. The LC50 value of AVM@EC@Pectin was 11.19 mg/L for PWN and 26.31 mg/L for JPS. The insecticidal activity of AVM@EC@Pectin was higher than that of the commercial emulsifiable concentrate (AVM-EC), and the photostability, adhesion, and target penetration were improved. The half-life (t1/2) of AVM@EC@Pectin was 133.7 min, which is approximately twice that of AVM-EC (68.2 min). Sprayed and injected applications showed that nanopesticides had superior bidirectional transportation, with five-times higher AVM contents detected in the roots relative to those of AVM-EC when sprayed at the top. The safety experiment showed that the proposed treatment had lower toxicity and higher safety for nontarget organisms in the application environment and human cells. This study presents a green, safe, and effective strategy for the integrated management of PWN disease.

Female proportion has a stronger influence on dispersal than body size in nematodes of mountain lakes.

Nematodes disperse passively and are amongst the smallest invertebrates on Earth. Free-living nematodes in mountain lakes are highly tolerant of environmental variations and are thus excellent model organisms in dispersal studies, since species-environment relationships are unlikely to interfere. In this study, we investigated how population or organism traits influence the stochastic physical nature of passive dispersal in a topologically complex environment. Specifically, we analyzed the influence of female proportion and body size on the geographical distribution of nematode species in the mountain lakes of the Pyrenees. We hypothesized that dispersal is facilitated by (i) a smaller body size, which would increase the rate of wind transport, and (ii) a higher female proportion within a population, which could increase colonization success because many nematode species are capable of parthenogenetic reproduction. The results showed that nematode species with a low proportion of females tend to have clustered spatial distributions that are not associated with patchy environmental conditions, suggesting greater barriers to dispersal. When all species were pooled, the overall proportion of females tended to increase at the highest elevations, where dispersal between lakes is arguably more difficult. The influence of body size was barely relevant for nematode distributions. Our study highlights the relevance of female proportion as a mechanism that enhances the dispersal success of parthenogenetic species, and that female sex is a determining factor in metacommunity connectivity.