Root-knot nematodes (RKN) are globally distributed and highly pathogenic. By determining the threshold at which damage occurs, we can create effective measures to protect plants from nematodes. In our study, we investigated the impact of ten initial population densities (Pi-log series) of M. javanica, i.e., 0, 2.38, 2.68, 2.98, 3.28, 3.58, 3.88, 4.18, 4.48 and 4.78 juveniles (J2) g(-1) soil on tomato cv. S22 plants in pots. The graphical estimation of yield losses caused by RKN was calculated using Seinhorst's yield loss model based on the relationship between the RKN population and damage to tomato plants. The relationship between initial nematode population density (Pi) and plant yield was analyzed using Seinhorst's model, where T is the tolerance limit, m is the minimum yield, and z is a constant describing yield decline. This allowed us to determine the threshold at which nematode infestation significantly reduces tomato growth. Seinhorst's model, y = m + (1-m) 0.95(Pi/T-1) for Pi > T; y = 1 for Pi <= T for RKN, was fitted to the data of shoot length and fresh weight of infected and uninoculated control plants to estimate the damage threshold level. The impact of M. javanica on plant physiological parameters, including chlorophyll content, carotenoid and nitrate reductase activity, root-gall formation, and disease incidence, was also determined in this study. The tolerance limits for relative tomato shoot length and fresh weight were 3.34 J2 of M. javanica g(-1) soil. The minimum relative values (y(m)) for shoot length and fresh weights were 0.39 and 0.42, respectively. We found that the damage threshold level was between 3.28 and 3.58. The root galls index, nematode population and reproduction factors were 3.75, 113 and 29.42, respectively, at an initial population density (Pi) of 3.58 J2 g(-1) soil. The chlorophyll (0.43 mg g(-1)), carotenoids (0.06 mg g(-1)) and nitrate reductase activity (0.21 mu mol min(-1) g(-1)). Our study highlights the importance of the accurate estimation of damage thresholds, which can guide timely and effective nematode management strategies.
Root-lesion nematodes, particularly Pratylenchus neglectus and P. crenatus (PNC), are widely distributed in New Zealand and cause significant damage to maize roots, reducing crop productivity. Despite their economic importance, no comprehensive assessment of commercial maize hybrids' resistance to PNC has been conducted in the country. Significant variation was observed in the nematode reproduction factor (Rf) and final population (Pf) among hybrids. In Experiment 1 (initial population (Pi) = 1250 PNC kg(-)(1) soil), Rf ranged from 3.1 in hybrid P8500 to 7.1 in hybrid P9127, with Pf values ranging from 3863 to 8903 PNC kg(-)(1) soil + roots in 45 days. In Experiment 2 (Pi = 750 PNC kg(-)(1) soil), Rf ranged from 18.4 in hybrid P1613 to 37.5 in hybrid P8805, with Pf values from 13,784 to 28,426 PNC kg(-)(1) soil + roots in 60 days. These results indicate active nematode reproduction and substantial hybrid-dependent variation in host response. Experiment 3 examined the impact of varying initial inoculum densities (500, 1000 and 1500 PNC kg(-)(1) soil), showing a dose-dependent increase in Pf and corresponding root damage. Susceptible hybrid (P9127) exhibited up to 42% root dry weight and 22% shoot dry weight reductions. This study is the first systematic evaluation of PNC resistance in New Zealand maize hybrids. It identifies P9127 and P8805 as highly susceptible, and P0891, P8500, and P1613 as moderately resistant. These findings offer valuable benchmarks for future breeding and support nematode management in New Zealand.
Root-knot nematodes Meloidogyne spp. are sedentary endoparasites that infest a wide range of plant species; they are also widely distributed, making them one of the most economically significant pests. Similarly, damage caused by Aphelenchoides fragariae can lead to substantial reductions in both crop yield and quality. This research focused on the rhizosphere of Helianthus tuberosus L. (variety Albik), grown in a Polish plantation. The experiment was conducted at the National Institute of Horticultural Research in Skierniewice, using concrete rings filled with medium sandy soil amended with 10% peat. The treatments included the following: control (no amendments), silver solution (Ag+) (120 mg/L soil), and vermicompost (Ve) (20 L of Eisenia fetida vermicompost). Each treatment was replicated four times. Compared with control, (Ve) significantly decreased the numbers of Aphelenchoides fragariae and Meloidogyne hapla, by about 48% and 31%. The application of (Ag+) led to the most significant reduction in population density in both nematode species, with A. fragariae decreasing by over 67% and M. hapla by approximately 75%.
Subterranean termites, Anacanthotermes ochraceus, are a widely distributed and mainly recognized in Saudi Arabia as agricultural pests and economically serious insects causing damage to wood structures. Because termites have a cryptic feeding habit and have developed resistance to several insecticides, the effectiveness of most synthetic insecticides against them has been diminished. This study was designed in laboratory using sawdust and sand bioassay to confirm six native entomopathogenic nematode (EPN) isolates' effectiveness including Steinernema feltiae NEM-29, S. feltiae AHN, Heterorhabditis indica NEM-19, H. indica NEM-18, H. bacteriophora NEM-26 and H. bacteriophora AHN22 against workers of A. ochraceus. Results revealed that termite worker mortality was higher in the sawdust bioassay than in sand bioassay. At both tested assay methods, S. feltiae had a significantly greater mortality rate, followed by H. indica and H. bacteriophora. The maximum mortalities (100% and 79.0%) was recorded for S. feltiae AHN at 1000 IJs/termite with lower LC50 values of 7.3 and 73.8 IJs/termites at 16 d-post exposure in sawdust and sand assay, respectively. All tested EPN strains reproduced successfully and emerged from dead A. ochraceus workers in 8-14 days with higher reproduction rate (22,193 IJs/termite) for S. feltiae AHN in sawdust bioassay. Conclusively, it has been discovered that native EPNs can control termites more successfully, presumably due to they have the ability to spread further infections via infected dead individuals and can directly interact with termite pests in the soil.
Reptiles rely on hibernation to survive harsh winters, but climate change and pesticide use in agriculture jeopardize their survival, making the ecosystem vulnerable. S-metolachlor (SM), a commonly found herbicide in soil, and its metabolite metolachlor oxanilic acid (MO) induce oxidative stress and disrupt reproductive hormones. In this study, lizards were exposed to SM- and MO-contaminated soil for 45 days during hibernation. Weight loss and deaths occurred at the beginning of hibernation in all groups. Furthermore, the exposure group experienced severe oxidative stress and damage in the liver, kidney, heart, gonad, and brain. The testosterone levels significantly decreased in male lizards in both the SM and MO groups, whereas estradiol levels increased significantly in female lizards in the SM group. Gender-specific expression of steroidogenic-related genes in the brains and gonads of lizards was observed. Histological analysis revealed toxic effects induced by both SM and MO in vital organs during hibernation. Moreover, MO induced more severe reproductive toxicity in male lizards during hibernation. Therefore, this study suggests gender-specific toxic effects were observed in hibernating lizards exposed to SM and MO, underscoring the importance of vigilant monitoring of pesticide application in agriculture and assessing the potential harm of its metabolites.
Endocrine-disrupting compounds (EDCs) are ubiquitous in soil, posing serious risks to soil biota, especially earthworms, which have been found to be affected by these compounds, despite not being their typical target organisms. Earthworms are essential for sustaining soil health and quality, by promoting soil aeration, organic matter decomposition and nutrient cycling, among other functions. This review synthesizes available literature evidencing the negative impact of EDC exposure, through traditional endocrine pathways and other toxicological mechanisms, on histopathological, biochemical, molecular and reproductive endpoints of earthworms. The compounds described, in the consulted literature, to induce histopathological, biochemical, genotoxicity and molecular and reproductive alterations include antibiotics, antimicrobial additives, flame retardants, fragrances, fungicides, herbicides, hormones, inorganic ions, insecticides, organic UV filters, parabens, perfluoroalkyl substances, pesticides, petroleum derivatives, plasticizers and polychlorinated biphenyls. These compounds reach soil through direct application or via contaminated organic amendments and water derived from potentially polluted sources. The findings gather in the present review highlight the vulnerability of earthworms to a broad spectrum of chemicals with endocrine disrupting capacity. Additionally, these studies emphasize the physiological disruptions caused by EDC exposure, underscoring the critical need to protect biodiversity, including earthworms, to ensure soil quality and ecosystem sustainability. Ongoing research has provided insights into molecular mechanisms responsive to EDCs in earthworms, including the identification of putative hormone receptors that exhibit functional similarity to those present in vertebrates. In conclusion, this review emphasizes the impact of EDCs in earthworms, especially through non-hormonal mediated pathways, and addresses the need for strong regulatory frameworks to mitigate the detrimental effects of EDCs on soil invertebrates in order to safeguard soil ecosystems.
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds which are comprised of two or more fused benzene rings. As a typical environmental pollutant, PAHs are widely distributed in water, soil, atmosphere and food. Despite extensive researches on the mechanisms of health damage caused by PAHs, especially their carcinogenic and mutagenic toxicity, there is still a lack of comprehensive summarization and synthesis regarding the mechanisms of PAHs on the gut-testis axis, which represents an intricate interplay between the gastrointestinal and reproductive systems. Thus, this review primarily focuses on the potential forms of interaction between PAHs and the gut microbiota and summarizes their adverse outcomes that may lead to gut microbiota dysbiosis, then compiles the possible mechanistic pathways on dysbiosis of the gut microbiota impairing the male reproductive function, in order to provide valuable insights for future research and guide further exploration into the intricate mechanisms underlying the impact of gut microbiota dysbiosis caused by PAHs on male reproductive function.
With an increase in the generation of sewage sludge, there comes a demand for disposal methods for it, and agricultural use is a sustainable alternative. However, there are gaps regarding emerging pollutants, especially in the pharmaceutical class. Nimesulide - an anti-inflammatory pharmaceutical recently associated with liver damage and banned in some European countries - is among the most consumed pharmaceuticals in Brazil hence can be found in wastewater and, therefore, in sewage sludge used for agriculture at ng L-1 concentrations. The objective of this research was to evaluate the toxicity of the anti-inflammatory pharmaceutical nimesulide through toxicity tests using the organism Enchytraeus crypticus in both natural and artificial soils, adopting concentrations about studies carried out with other anti-inflammatory drugs on seeds in the soil. In this work, the toxicity of nimesulide was evaluated in natural tropical soil sampled in Sao Paulo - Brazil, and in tropical artificial soil. The invertebrate E. crypticus was exposed to nimesulide nominal concentrations of 200; 340; 578; 982 and 1670 mg nimesulide kg-1 of dry soil and the reproduction test was performed according to ISO 16.387 (2014) standard, with 5 replicates per concentration. The results obtained through reproduction testing with E. crypticus in each concentration presented were EC50 values of 699 and 759 mg nimesulide Kg-1 dry soil, respectively for both natural and artificial soil. The Tukey test showed no significant difference between the soils, however. Finally, this study suggests that the anti-inflammatory drug nimesulide displays a toxicological effect on the reproduction of soil fauna organisms in high concentrations. Therefore, stresses the importance of identifying and monitoring unknown concentrations of this emerging pollutant in the environment.
The in vitro seed propagation of small seeded Campanula species often incurs com-plications in the manual handling of the tiny seed material from seed sterilisation to seedling transplantation in soil. The lack of a simple and effective protocol which minimises manual operations makes the propagation of such species both chal-lenging and inefficient. This study aimed to develop a protocol for the seed repro-duction of threatened Campanula and other threatened small-seed plant species. The method was successfully tested on Campanula bayerniana subsp. bayerniana. The saplings were cultivated over a 5-month period through seed germination un-der in vitro conditions followed by their transfer to containers with a soil mix. The protocol employs small filter paper discs on which the seeds germinate and con-tinue their development in soil substrate until the full biodegradation of the discs. The method involves surface treatment of the seeds with potassium permanganate solution, thus avoiding additional washing phases and direct contact with the seeds and seedlings, thereby preventing mechanical damage. This also facilitates the han-dling of each seed separately, minimising seed loss particularly when working with a small number of seeds. This study is also the first known example of the ex situ propagation of Campanula bayerniana