Nematode Diversity Research Articles

Diversity of plant-parasitic nematodes associated with chickpea (Cicer arietinum L.) in the main growing areas of Ethiopia

Summary Chickpea is one of the most important legume crops in Ethiopia; however, its production is far below the mean international chickpea production due to biotic and abiotic stressors. Plant-parasitic nematode infestation is extensive in chickpea-growing areas worldwide. The distribution and population density of plant-parasitic nematodes in chickpea were determined during the September-December 2021 growing season. Ten plant-parasitic nematode taxa were identified from 27 localities across ten districts in the main chickpea-growing areas in Ethiopia. Pratylenchus had the highest prominence values, followed by Rotylenchulus and Meloidogyne spp. Helicotylenchus, Hoplolaimus, Scutellonema and Quinisulcius were more prevalent than Criconemoides and Ditylenchus. Sequences of different molecular markers, including D2-D3 of 28S rDNA, ITS of rDNA, and COI and Nad5 of mtDNA, revealed the presence of Meloidogyne javanica, Rotylenchulus parvus, Scutellonema clathricaudatum and Helicotylenchus caudatus. Helicotylenchus caudatus and R. parvus are the first reports from Ethiopia and chickpea, while S. clathricaudatum is the first report for chickpea. This study provides essential baseline information of nematode pest occurrence on chickpea in Ethiopia. This information will raise awareness among growers, agricultural officers, and extension advisors, enabling them to develop effective nematode management strategies for the chickpea production system in Ethiopia.

Investigations on Nematode Community Dynamics on Pepper Monoculture Vegetations in Otuoke, Bayelsa State, Nigeria

Cultivation of Pepper, a vegetable fruit crop of prominence in Otuoke, is often hampered by parasitic nematode infestation. This negatively affects its economic impact on the rural domestic market. Farmers in Otuoke often ascribe reduced yield to inadequate farming strategy, as they are ignorant of nematode dynamics and resulting damages. This study sought to assay soil and roots of pepper plants for the determination of nematode community dynamics with a view of winging-in rural affordable management option for the agronomical parasites. The soil was collected using a hand trowel and roots were gotten using a knife and the extraction of the parasites was achieved by the use of the modified sieve plate method. The actual assemblage of nematodes was 397 from 11 genera, 205 (51.6%) occurred in farm A and 192 (48.4%) were seen in farm B. Dynamics on nematode diversity and occurrence were seen among species between farms. Meloidogyne species (17.9%) display variable populations between Farms A (19.5%) and B (16.1%). Tylenchorhynchus (11.3%) had a higher number in farm A (14.1%) and unlike in farm B (8.3%). However, Gracilachus (3.0%) and Scutellonema (7.3%)) species were reportedly found in Farm A while Tylenchus (6.5%) Hemicyclophora (5.3%) Pratylenchus (10.1%) and Rotylenchus species (10.1%) were peculiar to farm B. The result suggests that extensive fluctuations in nematode assemblage are possible even in fields with similar characteristics. Nematode occurrence on the root tissue of pepper plants in this study implies danger to quality productivity. Therefore, farmers should adopt poultry filters as manure for the cultivation of crops in the area. Farmers should also adopt exposing agricultural land to direct sunshine for a minimum of three weeks after clearing before tillage. The heat will help inhibit nematode profusion and check population abundance in soil for proper cultivation of crops.

Setting an Environmental Baseline for the Deep-Sea Slope Offshore Northwestern Cuba (Southeastern Gulf of Mexico) Using Sediments and Nematode Diversity

Deep-sea offshore northwestern Cuba is the less studied zone of the Gulf of Mexico (GoM). Our study aimed to set an environmental baseline and investigate a potential west-east gradient of sediment properties and nematode diversity along the northwestern Cuba. Sediments were collected by multicorer at nine sites in the insular slope between 974 and 1682 m depth. Sediment texture and composition showed a west-east gradient caused likely by narrowing of shelf width and increasing of downslope transport of terrigenous material. We found clear signatures of heavy metal pollution likely derived from Havana City but also from open-sky mining (Castellanos mining complex) and port dredging operations (Mariel). Nematode assemblages were dominated by the deep-sea genera: Acantholaimus, Metadasynemella, Desmodorella, Cervonema, Daptonema, Halalaimus, and Pselionema. α-diversity was about 20–50 genera and γ-diversity of about 100 genera. The β-diversity was substantial likely because small-scale patchiness of resources and heavy metals stress that increased assemblage variability. Individual weight decreased with depth indicating food-supply limitation in the deep sea; also, heavy metals were negatively correlated with weight suggesting deleterious effects on the growing. Our findings indicate that heavy metal pollution has reached deep-sea sediments and corroborate the long-range effects of anthropogenic activities on deep sea. Taxonomic diversity and biological traits (life strategy and trophic composition) constituted a powerful bioindicator of benthic health and benchmark for future potential disturbances in the region. Northwestern Cuba slope is still an understudied portion of the GoM and more research is needed to fully understand its biodiversity and biogeochemical patterns.

Grazing alters the soil nematode communities in grasslands: A meta-analysis

Grazing causes great disturbances in grassland ecosystems and may change the abundance, diversity, and ecological function of soil biota. Because of their important role in nutrient cycling and as good environmental indicators, nematodes are very representative soil organisms. However, the mechanisms by which grazing intensity, livestock type, duration, and environmental factors (e.g., climate and edaphic factors) affect soil nematodes remain poorly understood. In this study, we collected 1964 paired observations all over the world from 53 studies to clarify the grazing response patterns of soil nematodes and their potential mechanisms. Overall, grazing significantly decreased the abundance of bacterial-feeding (BF) nematodes (−16.54%) and omnivorous-predatory (OP) nematodes (−36.81%), and decreased nematode community diversity indices (Shannon–Weiner index: −4.33%, evenness index: −9.22%, species richness: −5.35%), but had no effect on ecological indices under a global regional scale. The response of soil nematodes to grazing varied by grazing intensity, animals, and duration. Heavy grazing decreased OP nematode abundance, but had no effect on the abundance of other trophic groups, or on diversity or ecological indices. Grazing by small animals had stronger effects than that by large animals and mixed-size animals on BF, fungal-feeding (FF), plant-feeding (PF) and OP nematodes, the Shannon–Wiener index, and the species richness index. The abundance of FF and OP nematodes influenced significantly under short-term grazing. The evenness index decreased significantly under long-term grazing (>10 years). Climate and edaphic factors impacted the effects of grazing on nematode abundance, diversity, and ecological indices. When resources (i.e., rain, heat, and soil nutrients) were abundant, the negative effects of grazing on nematodes were reduced; under sufficiently abundant resources, grazing even had positive effects on soil nematode communities. Thus, the influence of grazing on soil nematode communities is resource-dependent. Our study provides decision makers with grazing strategies based on the resource abundance. Resource-poor areas should have less grazing, while resource-rich areas should have more grazing to conserve soil biodiversity and maintain soil health.

Newly identified nematodes from the Great Salt Lake are associated with microbialites and specially adapted tohypersaline conditions.

Extreme environments enable the study of simplified food-webs and serveas models for evolutionary bottlenecks and early Earth ecology. Weinvestigated the biodiversity of invertebrate meiofauna in the benthic zone of the Great Salt Lake (GSL), Utah, USA, one of the most hypersaline lake systems in the world. The hypersaline bays within the GSL are currently thought to support only two multicellular animals: brine fly larvae andbrine shrimp. Here, we report the presence, habitat, and microbial interactions of novel free-living nematodes. Nematode diversity drops dramatically along a salinity gradient from a freshwater river into the south arm of the lake. In Gilbert Bay, nematodes primarily inhabit reef-like organosedimentary structures built by bacteria called microbialites. These structures likely provide a protective barrier to UV and aridity, and bacterial associations within them may support life in hypersaline environments. Notably, sampling from Owens Lake, another terminal lake in the Great Basin that lacks microbialites, did not recover nematodes from similar salinities. Phylogenetic divergence suggests that GSL nematodes represent previously undescribed members of the family Monhysteridae-one of the dominant fauna of the abyssal zone and deep-sea hydrothermal vents. These findings update our understanding of halophile ecosystems and the habitable limit of animals.

Eksplorasi Populasi dan Kepadatan Genus Nematoda Parasit pada Rizosfir Tanaman Kopi di Kota Solok, Sumatera Barat

Coffee is a plantation crop that has high economic value among other plantation crops and plays an important role as a source of foreign exchange for the country. The decline and low productivity of coffee plants in coffee production centers in Solok City, West Sumatra is one of the causes of plant parasitic nematode attacks. This nematode attack causes disrupted plant growth and reduces the value of crop production both in quantity and quality. This study aims to determine the diversity and population density of parasitic nematodes in the rhizosphere of coffee plants in Solok City, West Sumatra. This research was conducted from March to July 2023 at the Laboratory of Biological Control, Department of Plant Protection, Faculty of Agriculture, Andalas University. Soil samples were taken in two central areas of coffee plantations in Solok City, West Sumatra. In the rhizosphere of coffee plants in Solok City, four genera of parasitic nematodes were found, namely: the genera Pratylenchus, Helicotylenchus, Meloidogyne, Rotylenchulus, Paratylenchus, and Tylenchorhynchus. The highest frequency of presence of nematodes, namely the genus Rotylenchulus, was 50.99 belonging to the medium category in Jorong Kayu Aro, and 44.80 in the rare category in Jorong Kayu Jao.

Optimising high-throughput sequencing data analysis, from gene database selection to the analysis of compositional data: a case study on tropical soil nematodes

Optimising high-throughput sequencing data analysis, from gene database selection to the analysis of compositional data: a case study on tropical soil nematodes

Drought shifts soil nematode trophic groups and mediates the heterotrophic respiration

Abstract As the most diverse metazoan taxa, soil nematodes serve a diversity of functions in soil food webs and thus can regulate microbial community composition and affect organic matter decomposition and nutrient turnover rates. Because nematodes depend on water films to access food resources, drought can negatively affect nematode–microbial food webs, yet the impacts of drought on nematode diversity and abundance and how these changes may influence food web members and their functions are hardly explored. Here, we coupled research along a drought gradient in arid and semiarid grasslands with a detailed intact plant–soil microcosm experiment to explore the patterns and mechanisms of how drought impacts nematode abundance and carbon footprint, microbial phospholipid fatty acid (PLFA) and heterotrophic soil respiration. Overall, in the field and the microcosm experiments, we found that nematode abundance, carbon footprint and diversity, microbial PLFA and heterotrophic respiration were reduced under drier conditions. In addition, drought altered nematode and microbial community composition, through reducing the nematode channel ratio and increasing the relative fungivorous nematode abundance and the fungal to bacterial ratio. The soil decomposition channel shifted from a bacterial to a fungal pathway in response to drought, indicating decelerated heterotrophic respiration under drought. These results highlight the important contribution of soil nematodes and their associated microbial food web to soil carbon cycling. Our findings underscore the need to incorporate key soil fauna into terrestrial ecosystem model evaluation.

Drivers of plant parasitic nematode community structures associated with tobacco‐growing areas in southern Brazil

AbstractTobacco (Nicotiana tabacum L.) is one of the most important crops in southern Brazil, but little is known about the distribution and diversity of plant parasitic nematodes (PPNs). We surveyed the occurrence and diversity of PPNs in 36 tobacco‐growing areas in southern Brazil as well as evaluated their relationship with 19 bioclimatic variables. For these purposes, extracted nematodes (from soil and roots) were identified based on morphological and biochemical traits and estimates of incidence and abundance were obtained, which were used to compute diversity indices. Furthermore, the relationship between taxa and diversity and the influence of bioclimatic variables were studied using principal component analysis (PCA) and generalized linear models (GLMs), respectively. We observed diversity across the sampled sites, with values varying from 0.03 to 1.22 and from 0.05 to 0.76 according to the Shannon‐Wiener and Pielou's evenness indices, respectively. Seven genera of PPNs (Meloidogyne, Helicotylenchus, Tylenchus, Xiphinema, Pratylenchus, Paratylenchus and Mesocriconema) were identified, highlighting taxa with high incidence and abundance, such as Meloidogyne (100%; 1800 to 41,850 specimens/250 cm3), Helicotylenchus (100%; 50 to 9850 specimens/250 cm3), and Pratylenchus (86.1%; 50 to 1950 specimens/250 cm3). The PCA disclosed the major roles of Meloidogyne, Tylenchus, and Helicotylenchus in the structure of the PPN communities and their interplays. Among root‐knot nematodes, Meloidogyne javanica, M. arenaria and M. incognita were the predominant species. Using GLMs, we found that average annual temperature and annual precipitation strongly influenced the abundance of PPNs as well as the diversity indices (p < .01), with negative and/or positive interactions. Collectively, our findings fill gaps in knowledge about the current impact of PPNs and provide insights into future scenarios, including for other host crops.

Abundance, diversity and distribution of soil nematodes in Kangaita and Weru tea catchments of Kirinyaga and Tharaka Nithi counties, Kenya

Nematodes are the most abundant animals on earth and play essential roles in ecosystem functioning hence their abundance and diversity affect soil health. Nematodes have been reported in tea fields in some parts of Kenya and previous studies indicate that they may be a cause for the decline of tea population in some tea fields in Kenya. Nematodes of Moloidogyne spp have also been reported to be responsible for death of tea plants in nursery conditions. A survey was carried out in Weru and Kangaita tea factories catchment areas in Tharaka Nithi and Kirinyaga counties respectively. The survey aimed to determine the abundance and diversity of nematodes in small holder tea farms. Kangaita represented the high elevation site while Weru represented the low elevation site. Soil samples were collected from smallholder tea farms from which nematodes were extracted, identified based on their morphological characteristics, and classified according to their feeding habits then quantified using standard protocols. Nematodes from 23 genera were recovered in the two study sites representing all the five feeding groups: plant feeders, fungal feeders, bacterial feeders, omnivores, and predatory nematodes. Of the 23 genera, 11 were plant feeders, 6 bacterial feeders, 3 fungal feeders 2 omnivores and 1 predatory nematode. Kangaita, being a high elevation site reported higher population density in most genera reported than Weru which is a low elevation site. This is a departure from most studies that have reported higher nematode population densities in low altitudes. This can be attributed to differences in climatic and soil conditions in the two study sites in the same season. Kangaita was cooler with deep, well-ventilated, and loose soils while Weru was hotter with mostly compacted, shallow, and poorer soils in the tea farms. There is need for further research on the effect of elevation and farming practices on the distribution, abundance, and diversity of nematodes in tea fields. Key words: Nematodes, abundance, soil health, tea fields, elevation, diversity, feeding group

Characterisation of Paratylenchus cacao n. sp. from Ghana, and P. enigmaticus (Nematoda: Paratylenchinae) from Belgium

Summary Paratylenchus cacao n. sp., a pin nematode associated with cocoa (Theobroma cacao L.) from Ghana, is described herein based on morphology, morphometrics and phylogenetic relationships with other species. Morphologically, P. cacao n. sp. is characterised by a female body length of 174-265 μm, body assuming a ‘C’ or ‘J’ shape after heat relaxation, a flat head, slightly set off lip region, a truncated anterior end, a rigid stylet of 24-31 μm, four lateral lines, vulval region with distinct vulval flaps, and a finely rounded tail with a mucron-like terminus. The findings of the phylogenetic analyses utilising the D2-D3 expansion segments of 28S, ITS of rDNA, and COI of mitochondrial DNA sequences indicate that P. cacao n. sp. is a species closely related to P. leptos. Additionally, based on butterhead lettuce and leek populations from Belgium, the first description of a male, SEM pictures and COI sequences of P. enigmaticus are presented. Both studies exemplify how even potentially important plant-parasitic nematode species can remain unnoticed for a long time. This suggests the need to conduct more nematode diversity studies and underscores the significance of correct nematode identification through the utilisation of tools such as integrative taxonomy.

Effects of drought-induced stress on nematode communities in aquatic and terrestrial habitats of the Nebraska Sandhills

IntroductionGlobal change events (e.g., worsening drought) are increasing environmental stress in a variety of terrestrial and aquatic habitats. The degree to which communities in soils and sediments are driven by temporal environmental changes across multiple habitat types from the same region is not clear.MethodsWe used nematodes, a common bioindicator of soil and sediment health, to determine how community diversity and composition are altered by rising alkalinity across lakes, shorelines, and prairies in the western Nebraska Sandhills. We sampled these three habitats from five lake basins spanning an alkalinity gradient (pH 7–11) across three years (2019, 2020, 2021). During our sampling, the Sandhills experienced a range of drought intensities, with 2019 being a wet year, followed by severe drought in 2020, and abnormally dry/moderate drought in 2021. To determine if diversity and composition of nematodes responded to increased alkalinity and drought-induced stress we used different modelling approaches, including Random Forest and pairwise comparisons.Results and discussionOverall, nematode diversity in lakes was most affected by increasing alkalinity over time, whereas in shorelines and prairies diversity was most reliant on bacterial diversity and potential nematode-nematode interactions. In comparison to shorelines and prairies, community composition in lakes was the least variable and consistently driven by pH and lake water levels. In contrast, compositions in the shorelines and prairies were more variable and explained at varying degrees by pH, year, lake basin, and climate-associated variables. In addition, relative abundance and compositional nature of select copious taxa were highly unpredictable, indicating potential instability in these habitats. Future research is necessary to address the ecologic stability of the Sandhills and determine where conservation efforts are most needed.

STEINERNEMA ADAMSI N. SP. (RHABDITIDA: STEINERNEMATIDAE), A NEW ENTOMOPATHOGENIC NEMATODE FROM THAILAND.

A new species of entomopathogenic nematode, Steinernema adamsi n. sp., was recovered from the soil of a longan tree (Dimocarpus sp.) in Mueang Lamphun District, Thailand, using baiting techniques. Upon analysis of the nematode's morphological traits, we found it to be a new species of Steinernema and a member of the Longicaudatum clade. Molecular analyses of the ITS rDNA and D2D3 of 28S rDNA sequences further confirmed that S. adamsi n. sp. is a new species of the Longicaudatum clade, which is closely related to Steinernema guangdongense and Steinernema longicaudam. Using morphometric analysis, the infective juveniles measure between 774.69 and 956.96 μm, males have a size range of 905.44 to 1,281.98 μm, and females are within the range of 1,628.21 to 2,803.64 μm. We also identified the symbiotic bacteria associated with the nematode based on 16S sequences as Xenorhabdus spp. closely related toXenorhabdus griffiniae. Furthermore, we have successfully assessed a cryopreservation method for the long-term preservation of S. adamsi n. sp. Successful cryopreservation of this new species will allow for the longer preservation of its traits and will be valuable for its future use. The discovery of this new species has significant implications for the development of effective biological control agents in Thailand, and our work contributes to our understanding of the diversity and evolution of entomopathogenic nematodes.

Grazing induces positive direct effect of shrubs on nematode diversity but suppresses indirect effects through microbial pathways

Grazing induces positive direct effect of shrubs on nematode diversity but suppresses indirect effects through microbial pathways

Altered litter stoichiometry drives energy dynamics of food webs through changing multiple facets of soil biodiversity

Global change in organismal stoichiometry and biodiversity is often correlated with energy dynamics in ecological networks that underpin the functioning of terrestrial ecosystems and services. However, we know little about which facets of biodiversity, such as taxonomic, functional, and phylogenetic diversity, account for most of the variation in the energy dynamics of ecological networks along litter stoichiometry gradients. Here, we quantified how multiple facets of biodiversity impact energy fluxes of soil food webs through time in agricultural fields incorporating litter from six plant species of varying C:N stoichiometry. We found that community biomass and energy flux in soil food webs decreased while community maintenance cost (i.e. energy flux to biomass ratio) increased with increasing litter C:N ratio. Taxonomic, functional, and phylogenetic diversity of soil nematodes declined along increasing litter C:N stoichiometry, and together explained 73 % and 51.3 % of variation in community biomass, 71.6 % and 49.2 % of variation in energy flux, and 59.8 % and 37.4 % of variation in community maintenance cost in early and later decomposition stages, respectively. Functional and taxonomic diversity were highly associated with energy dynamics in early decomposition stages, while phylogenetic diversity emerged as the central predictor in later decomposition stages. By identifying the crucial role of multi-faceted biodiversity conservation facilitated by low C:N litter in driving the energy dynamics of food webs, these findings shed new light on the applicability of energy dynamics for linking biodiversity and ecosystem functioning under global change scenarios.

Unravelling cryptic diversity in the Paratrichodorus allius-group species complex to resolve eight new species of the genus and new insights on the molecular phylogeny (Nematoda: Trichodoridae)

Abstract The stubby-root nematode genus Paratrichodorus comprises species of plant polyphagous ectoparasitic nematodes distributed worldwide and a few of them are plant virus-vectors (tobravirus). This is one of the most difficult nematode genera in terms of species identification, since it is phenotypically conserved with closely related species and is highly sensitive to the specimen fixation and preservation processes. Using an integrative and multidisciplinary taxonomy framework, we determined species boundaries among the Paratrichodorus populations from a P. allius species-complex sampled in cultivated and natural ecosystems across Spain. We support the hypothesis that nematode diversity of the P. allius species-complex remains underestimated and describe here a total of eight new species on the basis of detailed morphological and molecular characterization of 16 Paratrichodorus populations: Paratrichodorus asidonaensis sp. nov., Paratrichodorus benalupensis sp. nov., Paratrichodorus hinogerus sp. nov., Paratrichodorus litoralis sp. nov., Paratrichodorus paraallius sp. nov., Paratrichodorus rocianerus sp. nov., Paratrichodorus tarifaensis sp. nov., and Paratrichodorus uliaensis sp. nov. This study emphasizes the importance of properly applying a broad taxonomic framework in plant-parasitic nematodes. It is also relevant for plant health, since it correctly delimits species morphologically closed to the virus vector nematode, P. allius, and gives proper molecular markers for its unequivocal identification.

Weakened pelagic-benthic coupling on an Arctic outflow shelf (Northeast Greenland) suggested by benthic ecosystem changes

Arctic marine ecosystems are becoming more boreal due to climate change. Predictions of ecosystem change focus mainly on Arctic inflow or interior shelves, with few comprehensive studies on Arctic outflow regions. During September–October 2017, soft-bottom communities were sampled and benthic ecosystem processes were quantified at 12 stations on the Northeast Greenland shelf (outflow shelf) and compared to the last regional ecosystem study, conducted in 1992 and 1993. The benthic habitat was characterized in terms of sediment granulometry, pigment concentrations, and porewater chemistry (dissolved inorganic carbon, nutrients). Total abundance and biomass of macrobenthos and meiobenthos, bacterial abundance, porewater dissolved inorganic carbon and ammonium concentrations were higher on the outer shelf compared to locations adjacent to the Nioghalvfjerdsfjorden glacier at 79°N and the inner shelf stations (e.g., macrofauna: 1,964–2,952 vs. 18–1,381 individuals m−2). These results suggest higher benthic production in the outer parts of the NEG shelf. This difference was also pronounced in macrobenthic and meiobenthic community structure, which was driven mainly by food availability (pigments with 1.3–4.3 vs. 0.3–0.9 µg g−1 sediment, higher total organic carbon content and bacterial abundance). Compared to the early 1990s, warmer bottom water temperatures, increased number of sea-ice-free days and lower sediment pigment concentrations in 2017 were accompanied by decreased polychaete and increased nematode abundance and diversity, and a different community structure of nematode genera. The present study confirms previous reports of strong pelagic-benthic coupling on the NEG shelf, but highlights a possible weakening since the early 1990s, with a potential shift in importance from macrofauna to meiofauna in the benthic community. Increasing inflow of Atlantic water and decreasing volume transport and thickness of sea ice through the Fram Strait, probably affecting the Northeast Water Polynya, may be responsible, suggesting ecosystem-wide consequences of continued changes in sea-ice patterns on Arctic shelves.

Assessing the diversity of nematodes in the Store Mosse National Park (Sweden) using metabarcoding

The Store Mosse National Park in the south of Sweden was surveyed for nematode diversity and distribution using DNA metabarcoding. Fifty samples were collected from five vegetation types in the park across a range of habitats (e.g. soil, litter, lichens, sphagnum and roots). The other habitats, aside from soil and litter, were sampled in order to capture the diversity of nematodes that may be uniquely associated with them. Nematodes were characterised using the V7-V8 variable domain (~ 350 bp) of the 18S ribosomal RNA gene. We identified 46 families, 76 genera (21 new to Swedish fauna) and 60 species (31 new to Swedish fauna). Some nematodes showed strong associations with their habitats, especially at the species level. Although soil and litter supported the most diverse nematode communities, our results support a strong justification for sampling across different media types to quantify nematode diversity accurately. Soil and litter communities showed high levels of stability with balanced distribution of all the various trophic and coloniser-persister groups.

Determination of the soil health status of wheat fields in Tekirdağ, Türkiye, based on nematode diversity

Objective: A study was conducted in wheat cultivation areas in Tekirdağ to estimate the soil health of fields using nematode biodiversity indices.
 Material and Methods: In the study, nematode taxa identified in wheat fields were subjected to community and food web analyses and several indices were calculated to determine the health status of soils in sampled areas. 
 Results and Conclusion Nematodes belonging to 41 genera were identified in wheat fields. The mean values of 10 biodiversity indices calculated in each sampled field were as follows; the Maturity index (MI): 2.26±0.28; the Maturity index MI2-5: 2.32±0.33; the Shannon-Weiner diversity index (H′): 2.03±0.24, the Evennes (J′): 0.90±0.06, the Genera Richness index (GR): 8.32±3.17, the Channel index (CI): 91±20.44; the Basal index (BI): 42.35±12.66; the Enrichment index (EI): 41.93±14.3, the Structure index (SI): 33.6±26.49 and the Plant-parasitic (PPI) index: 2.89±0.17. The nematode faunal indices indicate that 21% of surveyed wheat fields have well-developed and 79% have degraded soil profiles.

A Study on Population Diversity of Citrus Nematodes in District Sargodha

A Study on Population Diversity of Citrus Nematodes in District Sargodha