Pub Date : 2024-01-09DOI: 10.1163/15685411-bja10305
Steffan P. Hansen, A. Malan, J. Haran, M. Dunn, P. Addison
Considerable progress has been made in the surveying, taxonomy, screening, mass production and formulation of entomopathogenic nematodes (EPN) and their associated symbiotic bacteria in South Africa. Steinernema yirgalemense isolate 157-C is one of the most promising native EPN candidates with regards to virulence, its broad insect-host spectrum, and can be readily mass-produced and formulated into a commercial product. The banded fruit weevils, Phlyctinus callosus sensu stricto and Phlyctinus xerophilus, previously grouped together under the Phlyctinus callosus sensu lato species concept, are native entimine weevils of economic importance to deciduous fruit, grapevine and berries in the Western Cape province of South Africa. This study investigated potential differences in baseline susceptibility of larvae and pupae of the two weevil species to S. yirgalemense in laboratory screenings. The test arena used was 24-well bioassay plates, with an inoculation concentration of 200 infective juveniles (IJ) insect−1 for larvae and 100 IJ insect−1 for pupae. Infection was determined 48 h and 96 h after inoculation. Field-efficacy of S. yirgalemense, applied at a concentration of 60 IJ cm−2, against larvae of the two weevil species was determined in an ecologically relevant semi-field trial. In all cases in vitro mass-produced IJ of S. yirgalemense were used. No baseline differential susceptibility between P. callosus and P. xerophilus larvae was obtained in laboratory screenings. Phlyctinus pupae were approximately twice as susceptible compared to larvae, with significant differences between bioassay batches. Approximately 45% control of P. xerophilus larvae was obtained after 96 h of exposure to S. yirgalemense in the field, differing significantly from the control and P. callosus treatment. Low levels of Phlyctinus larval infection by native EPN (confirmed as Heterorhabditis bacteriophora from one P. xerophilus cadaver) occurred in both control and EPN treatment groups under field conditions.
南非在昆虫病原线虫（EPN）及其相关共生细菌的调查、分类、筛选、大规模生产和配制方面取得了长足的进步。Steinernema yirgalemense 分离物 157-C 是最有前途的本地 EPN 候选者之一，它具有毒性强、昆虫寄主范围广等特点，而且可以很容易地大规模生产并配制成商业产品。带果象鼻虫（Phlyctinus callosus sensu stricto和Phlyctinus xerophilus）以前被归入Phlyctinus callosus sensu lato物种概念下，是对南非西开普省落叶水果、葡萄藤和浆果具有重要经济价值的本地象鼻虫。本研究调查了两种象鼻虫的幼虫和蛹在实验室筛选中对 S. yirgalemense 的基线敏感性的潜在差异。使用的试验场是 24 孔生物测定板，幼虫的接种浓度为 200 感染幼虫 (IJ) 昆虫-1，蛹的接种浓度为 100 感染幼虫 (IJ) 昆虫-1。接种后 48 小时和 96 小时测定感染情况。在与生态相关的半田间试验中，确定了施用浓度为 60 IJ cm-2 的 S. yirgalemense 对两种象鼻虫幼虫的田间药效。在所有情况下，都使用了体外大规模生产的 S. yirgalemense IJ。在实验室筛选中，没有发现 P. callosus 和 P. xerophilus 幼虫之间的基本敏感性差异。与幼虫相比，Phlyctinus 蛹的易感性约为幼虫的两倍，生物测定批次之间存在显著差异。在田间暴露于 S. yirgalemense 96 小时后，P. xerophilus 幼虫的控制率约为 45%，与对照组和 P. callosus 处理有显著差异。在田间条件下，对照组和 EPN 处理组的 Phlyctinus 幼虫都受到了本地 EPN（从一具 P. xerophilus 尸体中确认为细菌异型线虫）的低水平感染。
{"title":"Steinernema yirgalemense (Steinernematidae) to control Phlyctinus callosus and Phlyctinus xerophilus (Curculionidae)","authors":"Steffan P. Hansen, A. Malan, J. Haran, M. Dunn, P. Addison","doi":"10.1163/15685411-bja10305","DOIUrl":"https://doi.org/10.1163/15685411-bja10305","url":null,"abstract":"\u0000Considerable progress has been made in the surveying, taxonomy, screening, mass production and formulation of entomopathogenic nematodes (EPN) and their associated symbiotic bacteria in South Africa. Steinernema yirgalemense isolate 157-C is one of the most promising native EPN candidates with regards to virulence, its broad insect-host spectrum, and can be readily mass-produced and formulated into a commercial product. The banded fruit weevils, Phlyctinus callosus sensu stricto and Phlyctinus xerophilus, previously grouped together under the Phlyctinus callosus sensu lato species concept, are native entimine weevils of economic importance to deciduous fruit, grapevine and berries in the Western Cape province of South Africa. This study investigated potential differences in baseline susceptibility of larvae and pupae of the two weevil species to S. yirgalemense in laboratory screenings. The test arena used was 24-well bioassay plates, with an inoculation concentration of 200 infective juveniles (IJ) insect−1 for larvae and 100 IJ insect−1 for pupae. Infection was determined 48 h and 96 h after inoculation. Field-efficacy of S. yirgalemense, applied at a concentration of 60 IJ cm−2, against larvae of the two weevil species was determined in an ecologically relevant semi-field trial. In all cases in vitro mass-produced IJ of S. yirgalemense were used. No baseline differential susceptibility between P. callosus and P. xerophilus larvae was obtained in laboratory screenings. Phlyctinus pupae were approximately twice as susceptible compared to larvae, with significant differences between bioassay batches. Approximately 45% control of P. xerophilus larvae was obtained after 96 h of exposure to S. yirgalemense in the field, differing significantly from the control and P. callosus treatment. Low levels of Phlyctinus larval infection by native EPN (confirmed as Heterorhabditis bacteriophora from one P. xerophilus cadaver) occurred in both control and EPN treatment groups under field conditions.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"85 4","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139444710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-20DOI: 10.1163/15685411-bja10303
Larissa de B. Caixeta, J. V. D. L. D. Silva, Nancy Eunice Niño Castañeda, J. M. D. C. Castro, J. Cares
Brazilian Caatinga is one of the most diverse, seasonally dry, tropical forests of the world and is threatened by strong land use pressure and poor protection. One way of understanding changes in the soil conditions caused by anthropogenic activities is using the nematode assemblages as potential bioindicators. This study analysed changes in nematode communities in three different types of land use (natural forest-CA, natural area with accumulation of salts-SS, and agricultural growing areas, such as cover crops-CC for cattle and fruit trees-IC) in the Caatinga, in the sub-median region of the São Francisco River Valley (SFRV), Pernambuco, northeastern Brazil. We recorded a total of 63 262 nematode individuals, representing 42 genera, belonging to 23 families. Nematode abundance, diversity and maturity indices were highest in the CC and lowest in the SS. Among the nematode trophic groups, bacterivores, omnivores + predators and plant parasites were significantly affected by type of land use. Different soil properties were related to the differences in taxonomic composition among the natural and agricultural areas, accounting for 26.6% of the total variation. In general, our results indicate that soil salinisation and desertification in the natural areas, as well as soils subjected to cover crops and fruit tree production, significantly influenced the composition of nematode communities in the São Francisco River Valley.
巴西的 Caatinga 是世界上最多样化、季节性干旱的热带森林之一，受到土地使用压力大和保护不力的威胁。了解人为活动造成的土壤条件变化的一种方法是利用线虫群落作为潜在的生物指标。本研究分析了巴西东北部伯南布哥州圣弗朗西斯科河谷（SFRV）次中间地区卡廷加中三种不同土地利用类型（天然林-CA、盐分积累天然区-SS 和农业种植区，如牛和果树的覆盖作物-CC）中线虫群落的变化。我们共记录了 63 262 个线虫个体，代表 42 个属，隶属 23 个科。线虫丰度、多样性和成熟度指数在 CC 区最高，在 SS 区最低。在线虫营养群中，细菌食性、杂食性+捕食性和植物寄生性受土地利用类型的影响较大。不同的土壤特性与自然区和农业区分类组成的差异有关，占总差异的 26.6%。总之，我们的研究结果表明，自然区的土壤盐碱化和荒漠化以及种植覆盖作物和果树的土壤对圣弗朗西斯科河流域线虫群落的组成有很大影响。
{"title":"Nematodes as bioindicators of soil health in different land uses in the São Francisco River Valley, Brazil","authors":"Larissa de B. Caixeta, J. V. D. L. D. Silva, Nancy Eunice Niño Castañeda, J. M. D. C. Castro, J. Cares","doi":"10.1163/15685411-bja10303","DOIUrl":"https://doi.org/10.1163/15685411-bja10303","url":null,"abstract":"\u0000Brazilian Caatinga is one of the most diverse, seasonally dry, tropical forests of the world and is threatened by strong land use pressure and poor protection. One way of understanding changes in the soil conditions caused by anthropogenic activities is using the nematode assemblages as potential bioindicators. This study analysed changes in nematode communities in three different types of land use (natural forest-CA, natural area with accumulation of salts-SS, and agricultural growing areas, such as cover crops-CC for cattle and fruit trees-IC) in the Caatinga, in the sub-median region of the São Francisco River Valley (SFRV), Pernambuco, northeastern Brazil. We recorded a total of 63 262 nematode individuals, representing 42 genera, belonging to 23 families. Nematode abundance, diversity and maturity indices were highest in the CC and lowest in the SS. Among the nematode trophic groups, bacterivores, omnivores + predators and plant parasites were significantly affected by type of land use. Different soil properties were related to the differences in taxonomic composition among the natural and agricultural areas, accounting for 26.6% of the total variation. In general, our results indicate that soil salinisation and desertification in the natural areas, as well as soils subjected to cover crops and fruit tree production, significantly influenced the composition of nematode communities in the São Francisco River Valley.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"120 6","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138953765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-20DOI: 10.1163/15685411-bja10304
Clemen J. Oliveira, Natalia A. Peres, Johan Desaeger
Demand for Florida organic strawberries has significantly increased in recent years, yet this industry is threatened by pests and pathogens that often come with transplants from out-of-state nurseries. Plant steaming has been explored as an alternative to reduce those threats in transplants. This study evaluated the yield performance of seven strawberry cultivars and their impact on nematode densities and plant vigour after steaming was applied to transplants imported from California during two growing seasons (2020-2021 and 2021-2022). The cultivars used were ‘Sensation® Florida127’, ‘Florida Brilliance’, ‘Florida Radiance’, ‘Winterstar™ FL 05-107’, ‘Florida Elyana’, ‘Strawberry Festival’ and ‘Florida Beauty’. Plant steaming reduced plant vigour only 4 weeks after transplanting. Nevertheless, no negative effect was observed in total fruit yield. Differences among cultivars were observed for plant vigour, total fruit yield and abundance of root-knot nematodes. The plant vigour of each cultivar depended on the time of the year, which varied significantly throughout the season. Cultivars ‘Sensation® Florida127’ and ‘Florida Radiance’ attained the highest total yield in both seasons. There was an effect of the cropping system in the nematode community, which increased the bacterivores but drastically reduced omnivores and ring nematodes over time. No effect of cultivar was observed in plant-parasitic nematode populations. The cultivar ‘Winterstar™ FL 05-107’ was an exception since Meloidogyne javanica population densities were significantly higher in ‘Winterstar™ FL 05-107’s experimental plots. Overall, transplant steaming shows the potential to be a component of an integrated pest and disease management programme for the success of sustainable and profitable yields
{"title":"Nematode population dynamics and plant steaming effects on strawberry cultivars under organic field conditions in Florida","authors":"Clemen J. Oliveira, Natalia A. Peres, Johan Desaeger","doi":"10.1163/15685411-bja10304","DOIUrl":"https://doi.org/10.1163/15685411-bja10304","url":null,"abstract":"\u0000Demand for Florida organic strawberries has significantly increased in recent years, yet this industry is threatened by pests and pathogens that often come with transplants from out-of-state nurseries. Plant steaming has been explored as an alternative to reduce those threats in transplants. This study evaluated the yield performance of seven strawberry cultivars and their impact on nematode densities and plant vigour after steaming was applied to transplants imported from California during two growing seasons (2020-2021 and 2021-2022). The cultivars used were ‘Sensation® Florida127’, ‘Florida Brilliance’, ‘Florida Radiance’, ‘Winterstar™ FL 05-107’, ‘Florida Elyana’, ‘Strawberry Festival’ and ‘Florida Beauty’. Plant steaming reduced plant vigour only 4 weeks after transplanting. Nevertheless, no negative effect was observed in total fruit yield. Differences among cultivars were observed for plant vigour, total fruit yield and abundance of root-knot nematodes. The plant vigour of each cultivar depended on the time of the year, which varied significantly throughout the season. Cultivars ‘Sensation® Florida127’ and ‘Florida Radiance’ attained the highest total yield in both seasons. There was an effect of the cropping system in the nematode community, which increased the bacterivores but drastically reduced omnivores and ring nematodes over time. No effect of cultivar was observed in plant-parasitic nematode populations. The cultivar ‘Winterstar™ FL 05-107’ was an exception since Meloidogyne javanica population densities were significantly higher in ‘Winterstar™ FL 05-107’s experimental plots. Overall, transplant steaming shows the potential to be a component of an integrated pest and disease management programme for the success of sustainable and profitable yields","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"90 17","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138957866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-05DOI: 10.1163/15685411-bja10295
Christopher Ogaya, Yohannes Moges, Verena Dörfler, Mike Barg, R. Ehlers, Carlos Molina
Limited shelf life is a major constraint to successful commercialisation of entomopathogenic nematodes (EPN), and to extend shelf life, dauer juveniles (DJ) are formulated and stored at low temperatures (4-8°C). We evaluated the cold storage potential of strains of Heterorhabditis bacteriophora formulated in diatomaceous earth at storage temperatures between 5 and 9°C. When assessing DJ decline to reach 75% survival (MT75) in the formulation for the respective temperatures, H. bacteriophora strain HB4 had the highest survival of 25 days at 9°C, while strain D2D6 survived longest at 8°C for 28 days. A set of 22 H. bacteriophora wild type inbred lines was then phenotyped for cold tolerance in water under oxidative stress in 70 mM H2O2 at 2°C. The MT50 (time to 50% survival) ranged from 11 to 23 days. The phenotypic data were correlated with the respective genotypic data, identifying four single nucleotide polymorphic (SNP) markers associated with cold tolerance. The survival of two lines (PT11 and IR11) with opposite extreme cold tolerance pheno- and genotypes was evaluated in diatomaceous earth formulation at 2°C with the cold tolerant IR11 surviving 3 days longer than PT11. Our study yields a set of valuable SNP markers employable in rapid genotyping of cold tolerance and tracking this trait during the breeding process.
有限的保质期是昆虫病原性线虫(EPN)成功商业化的主要制约因素，为了延长保质期，我们配制了dawer幼虫(DJ)，并在低温(4-8°C)下储存。我们评估了在硅藻土中配制的异habditis bacteriophora菌株在5 - 9°C的储存温度下的冷藏潜力。在不同温度下，当评估配方中DJ下降达到75%存活率(MT75)时，菌株HB4在9°C下的存活率最高，为25天，而菌株D2D6在8°C下的存活率最长，为28天。在70 mM H2O2和2°C条件下，对22个野生型噬菌体自交系进行了耐冷表型分析。MT50(至50%生存时间)为11 ~ 23天。表型数据与各自的基因型数据相关，鉴定出4个与耐寒性相关的单核苷酸多态性(SNP)标记。在2°C硅藻土配方中，研究了具有相反极端耐寒表型和基因型的两个品系(PT11和IR11)的存活率，耐寒品系IR11比PT11多存活3天。我们的研究产生了一组有价值的SNP标记，可用于快速的耐寒性基因分型和在育种过程中跟踪该性状。
{"title":"Genotypic markers associated with cold storage survival of the entomopathogenic nematode Heterorhabditis bacteriophora","authors":"Christopher Ogaya, Yohannes Moges, Verena Dörfler, Mike Barg, R. Ehlers, Carlos Molina","doi":"10.1163/15685411-bja10295","DOIUrl":"https://doi.org/10.1163/15685411-bja10295","url":null,"abstract":"\u0000Limited shelf life is a major constraint to successful commercialisation of entomopathogenic nematodes (EPN), and to extend shelf life, dauer juveniles (DJ) are formulated and stored at low temperatures (4-8°C). We evaluated the cold storage potential of strains of Heterorhabditis bacteriophora formulated in diatomaceous earth at storage temperatures between 5 and 9°C. When assessing DJ decline to reach 75% survival (MT75) in the formulation for the respective temperatures, H. bacteriophora strain HB4 had the highest survival of 25 days at 9°C, while strain D2D6 survived longest at 8°C for 28 days. A set of 22 H. bacteriophora wild type inbred lines was then phenotyped for cold tolerance in water under oxidative stress in 70 mM H2O2 at 2°C. The MT50 (time to 50% survival) ranged from 11 to 23 days. The phenotypic data were correlated with the respective genotypic data, identifying four single nucleotide polymorphic (SNP) markers associated with cold tolerance. The survival of two lines (PT11 and IR11) with opposite extreme cold tolerance pheno- and genotypes was evaluated in diatomaceous earth formulation at 2°C with the cold tolerant IR11 surviving 3 days longer than PT11. Our study yields a set of valuable SNP markers employable in rapid genotyping of cold tolerance and tracking this trait during the breeding process.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"118 29","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138599386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-05DOI: 10.1163/15685411-bja10301
R. D. P. E. S. Ribeiro, A. Sobieranski, Elaine C.D. Gonçalves, Rafael C. Dutra, Aldo von Wangenheim
Analysing nematode behaviour helps estimate biomechanical parameters for applications like cellular biology, pharmacology and cognitive neuroscience. Portable holographic platforms offer cost-effective, high-resolution, high-frame-rate, wide-field imaging compared to conventional microscopy. Holographic methods can reconstruct original shapes using numerical diffraction, although this is computationally expensive. However, video holography remains challenging due to the fast motion and overlapping of holograms when nematodes swim in crowded environments. In this work we address this problem by focusing on automated detection and tracking of nematodes in densely populated environments, using machine learning methods. The main advantage of our approach is to present an automated computational flow to detect and analyse the behaviour of live nematodes in video directly from the raw holographic signals, without the requirement of phase-recovering methods for diffraction. For this purpose, we developed a three-step CNN-based approach consisting of: i) nematode hologram detection; ii) temporal tracking; and iii) behavioural analysis based on mobility parameters. In terms of precision, the obtained results show that using a two-stage detector, the Faster R-CNN architecture with the ResNet18 model as a backbone, presented the best Mean Average Precision (mAP) score with 86% for correct classification. For tracking, the best performing algorithm was IoU with a HOTA, resulting in 62.42% when applied on the individually tagged nematodes, which is comparable to the best current generic multi-tracking approaches available over the literature. Our obtained results show that the use of a convolutional neural network approach associated with a classic tracking algorithm is a very suitable approach for nematode detection and behavioural analysis for biological assays directly from holograms, even in densely populated environments. The proposed approach has been presented as a promising solution for automated inspection of free-living nematode individuals.
{"title":"Automated classification and tracking of microscopic holographic patterns of nematodes using machine learning methods","authors":"R. D. P. E. S. Ribeiro, A. Sobieranski, Elaine C.D. Gonçalves, Rafael C. Dutra, Aldo von Wangenheim","doi":"10.1163/15685411-bja10301","DOIUrl":"https://doi.org/10.1163/15685411-bja10301","url":null,"abstract":"\u0000Analysing nematode behaviour helps estimate biomechanical parameters for applications like cellular biology, pharmacology and cognitive neuroscience. Portable holographic platforms offer cost-effective, high-resolution, high-frame-rate, wide-field imaging compared to conventional microscopy. Holographic methods can reconstruct original shapes using numerical diffraction, although this is computationally expensive. However, video holography remains challenging due to the fast motion and overlapping of holograms when nematodes swim in crowded environments. In this work we address this problem by focusing on automated detection and tracking of nematodes in densely populated environments, using machine learning methods. The main advantage of our approach is to present an automated computational flow to detect and analyse the behaviour of live nematodes in video directly from the raw holographic signals, without the requirement of phase-recovering methods for diffraction. For this purpose, we developed a three-step CNN-based approach consisting of: i) nematode hologram detection; ii) temporal tracking; and iii) behavioural analysis based on mobility parameters. In terms of precision, the obtained results show that using a two-stage detector, the Faster R-CNN architecture with the ResNet18 model as a backbone, presented the best Mean Average Precision (mAP) score with 86% for correct classification. For tracking, the best performing algorithm was IoU with a HOTA, resulting in 62.42% when applied on the individually tagged nematodes, which is comparable to the best current generic multi-tracking approaches available over the literature. Our obtained results show that the use of a convolutional neural network approach associated with a classic tracking algorithm is a very suitable approach for nematode detection and behavioural analysis for biological assays directly from holograms, even in densely populated environments. The proposed approach has been presented as a promising solution for automated inspection of free-living nematode individuals.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"117 16","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138599698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-05DOI: 10.1163/15685411-bja10299
Kamal Neupane, Guiping Yan
The use of non-host cover crops can be a viable strategy for managing soybean cyst nematode (SCN) Heterodera glycines. Cover crops may affect SCN biology and reduce populations by acting as trap crops that promote the hatching and/or penetration by second-stage juveniles (J2) without supporting their development. Two growth chamber experiments were conducted to assess ten cover crops for their impacts on SCN hatching and penetration into the roots. For each experiment, with four replications per treatment, crops were planted in naturally-infested soil in two separate sets to be harvested 15 and 30 days after planting (DAP). SCN susceptible soybean ‘Barnes’ and non-planted natural soil (fallow) were used as controls. Faba bean ‘Petite’, a non-host of SCN, induced the greatest hatching among the cover crops and was statistically similar to soybean. Winter rye ‘ND Dylan’ also induced significant hatching compared to fallow. Root staining revealed that the highest number of J2 penetrated the faba bean roots at 15 DAP, followed by soybean and winter rye. While J2 penetrated all tested crops, they completed their development to become adult females only in soybean and turnip. Soybean cyst nematode development to adult females did not occur in faba bean, and the number of SCN inside the faba bean roots 30 DAP was significantly lower than at 15 DAP and also lower than in soybean. These results suggest that the faba bean affects SCN biology and has the greatest potential to act as a trap crop for managing SCN.
{"title":"Effects of cover crops on hatching of and root penetration by Heterodera glycines","authors":"Kamal Neupane, Guiping Yan","doi":"10.1163/15685411-bja10299","DOIUrl":"https://doi.org/10.1163/15685411-bja10299","url":null,"abstract":"\u0000The use of non-host cover crops can be a viable strategy for managing soybean cyst nematode (SCN) Heterodera glycines. Cover crops may affect SCN biology and reduce populations by acting as trap crops that promote the hatching and/or penetration by second-stage juveniles (J2) without supporting their development. Two growth chamber experiments were conducted to assess ten cover crops for their impacts on SCN hatching and penetration into the roots. For each experiment, with four replications per treatment, crops were planted in naturally-infested soil in two separate sets to be harvested 15 and 30 days after planting (DAP). SCN susceptible soybean ‘Barnes’ and non-planted natural soil (fallow) were used as controls. Faba bean ‘Petite’, a non-host of SCN, induced the greatest hatching among the cover crops and was statistically similar to soybean. Winter rye ‘ND Dylan’ also induced significant hatching compared to fallow. Root staining revealed that the highest number of J2 penetrated the faba bean roots at 15 DAP, followed by soybean and winter rye. While J2 penetrated all tested crops, they completed their development to become adult females only in soybean and turnip. Soybean cyst nematode development to adult females did not occur in faba bean, and the number of SCN inside the faba bean roots 30 DAP was significantly lower than at 15 DAP and also lower than in soybean. These results suggest that the faba bean affects SCN biology and has the greatest potential to act as a trap crop for managing SCN.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"77 12","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138598226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-14DOI: 10.1163/15685411-bja10297
Itani P. Guga, Willem P. Steyn, M. Marais, A. Swart, C. Girgan, A. Mbatyoti, F. N. Mudau, Dirk De Waele, M. Daneel
Bush tea (Athrixia phylicoides) is an aromatic, perennial, leafy shrub that is endemic to the northeastern mountain ranges of South Africa and has a high potential for commercialisation as an alternative to caffeine-containing tea. During the summer and winter of 2018-2019, a survey was carried out at nine localities in the northeastern regions of South Africa to study the diversity of nematodes associated with bush tea and, in terms of frequency of occurrence and abundance, identify the dominant plant-parasitic nematodes. Twenty-one plant-parasitic nematode species belonging to 14 genera were identified in 90 rhizosphere soil and root samples. Meloidogyne and Helicotylenchus were the dominant plant-parasitic nematode genera. Meloidogyne javanica and Scutellonema brachyurus were found at all localities, followed by M. enterolobii, Pratylenchus brachyurus, Rotylenchulus parvus, H. martini and S. truncatum (found at 7-8 localities). Other species identified included Criconema corbetii, C. sphaerocephalus, C. xenoplax, Criconemoides ihlathum, C. parvus, Discocriconemella glabrannulata, H. dihystera, H. erythrinae, H. paraplatyurus, Hemicycliophora typica, M. hapla, M. incognita, Rotylenchulus unisexus and R. clavicaudatus. Individuals of Crossonema, Paratylenchus, Ogma, the Xiphinema americanum-group and X. americanum sensu lato could not be identified to species level due to the low number of specimens present in the samples. Comparison of the two methods used to identify the Meloidogyne populations to species level shows that morphological identification (particularly perineal pattern morphology) provided a more complete picture of the Meloidogyne species present in the samples compared with the molecular SCAR-PCR technique. High levels of Cu, K and pH were associated with the highest relative population densities (RPD% = average population density of a nematode genus/total nematode population density × 100) of Meloidogyne, whilst high levels of Al and soil resistivity were associated with the lowest RPD% of Meloidogyne. By contrast, high levels of K and pH were associated with the lowest RPD% of Helicotylenchus, whilst high levels of Al and soil resistivity were associated with the highest RPD% of Helicotylenchus.
{"title":"Plant-parasitic nematodes associated with bush tea (Athrixia phylicoides) in South Africa and their relationship with physico-chemical soil properties","authors":"Itani P. Guga, Willem P. Steyn, M. Marais, A. Swart, C. Girgan, A. Mbatyoti, F. N. Mudau, Dirk De Waele, M. Daneel","doi":"10.1163/15685411-bja10297","DOIUrl":"https://doi.org/10.1163/15685411-bja10297","url":null,"abstract":"Bush tea (Athrixia phylicoides) is an aromatic, perennial, leafy shrub that is endemic to the northeastern mountain ranges of South Africa and has a high potential for commercialisation as an alternative to caffeine-containing tea. During the summer and winter of 2018-2019, a survey was carried out at nine localities in the northeastern regions of South Africa to study the diversity of nematodes associated with bush tea and, in terms of frequency of occurrence and abundance, identify the dominant plant-parasitic nematodes. Twenty-one plant-parasitic nematode species belonging to 14 genera were identified in 90 rhizosphere soil and root samples. Meloidogyne and Helicotylenchus were the dominant plant-parasitic nematode genera. Meloidogyne javanica and Scutellonema brachyurus were found at all localities, followed by M. enterolobii, Pratylenchus brachyurus, Rotylenchulus parvus, H. martini and S. truncatum (found at 7-8 localities). Other species identified included Criconema corbetii, C. sphaerocephalus, C. xenoplax, Criconemoides ihlathum, C. parvus, Discocriconemella glabrannulata, H. dihystera, H. erythrinae, H. paraplatyurus, Hemicycliophora typica, M. hapla, M. incognita, Rotylenchulus unisexus and R. clavicaudatus. Individuals of Crossonema, Paratylenchus, Ogma, the Xiphinema americanum-group and X. americanum sensu lato could not be identified to species level due to the low number of specimens present in the samples. Comparison of the two methods used to identify the Meloidogyne populations to species level shows that morphological identification (particularly perineal pattern morphology) provided a more complete picture of the Meloidogyne species present in the samples compared with the molecular SCAR-PCR technique. High levels of Cu, K and pH were associated with the highest relative population densities (RPD% = average population density of a nematode genus/total nematode population density × 100) of Meloidogyne, whilst high levels of Al and soil resistivity were associated with the lowest RPD% of Meloidogyne. By contrast, high levels of K and pH were associated with the lowest RPD% of Helicotylenchus, whilst high levels of Al and soil resistivity were associated with the highest RPD% of Helicotylenchus.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"51 6","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139277855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1163/15685411-bja10296
Mihail R. Kantor, Sergei A. Subbotin, Bill Im, Zafar A. Handoo
Summary A new needle nematode species, Longidorus patuxentensis n. sp., was collected along the banks of the Western Branch Patuxent River from Upper Marlboro, MD, USA, and described herein. Female body length of the new species ranges from 3.8 to 5.2 mm, with a set off lip region by depression, 77-92 μ m long odontostyle, 40-53 μ m long odontophore, vulva located at 46.3-50.1% and tail conoid with bluntly rounded tip. The new species has four juvenile developmental stages and no males. It looks morphologically similar to L. breviannulatus , L. elongatus , L. martini , L. americanus , L. grandis , L. sabalanicus and L. sturhani by having a ventrally curved to spiral body, generally similar lip region and conoid tail with a rounded terminus, but differs from these species by the odontostyle, odontophore, total stylet length and a few other characters. Phylogenetic analysis of the D2-D3 expansion segments of 28S rRNA gene sequences placed L. patuxentensis n. sp. in a clade with L. litchi , L. fangi , L. jonesi , L. diadecturus and Longidorus sp. The D2-D3 sequence of L. patuxentensis n. sp. was identical to that of Longidorus sp.5 collected from Juglans sp. growing in Butte County, California, USA. The D2-D3 of 28S and ITS1 rRNA and COI gene sequences indicated that the Maryland and California populations belong to the same species, described herein as L. patuxentensis n. sp.
{"title":"Morphological and molecular characterisation of Longidorus patuxentensis n. sp. (Nematoda: Longidoridae) from Maryland and California, USA","authors":"Mihail R. Kantor, Sergei A. Subbotin, Bill Im, Zafar A. Handoo","doi":"10.1163/15685411-bja10296","DOIUrl":"https://doi.org/10.1163/15685411-bja10296","url":null,"abstract":"Summary A new needle nematode species, Longidorus patuxentensis n. sp., was collected along the banks of the Western Branch Patuxent River from Upper Marlboro, MD, USA, and described herein. Female body length of the new species ranges from 3.8 to 5.2 mm, with a set off lip region by depression, 77-92 μ m long odontostyle, 40-53 μ m long odontophore, vulva located at 46.3-50.1% and tail conoid with bluntly rounded tip. The new species has four juvenile developmental stages and no males. It looks morphologically similar to L. breviannulatus , L. elongatus , L. martini , L. americanus , L. grandis , L. sabalanicus and L. sturhani by having a ventrally curved to spiral body, generally similar lip region and conoid tail with a rounded terminus, but differs from these species by the odontostyle, odontophore, total stylet length and a few other characters. Phylogenetic analysis of the D2-D3 expansion segments of 28S rRNA gene sequences placed L. patuxentensis n. sp. in a clade with L. litchi , L. fangi , L. jonesi , L. diadecturus and Longidorus sp. The D2-D3 sequence of L. patuxentensis n. sp. was identical to that of Longidorus sp.5 collected from Juglans sp. growing in Butte County, California, USA. The D2-D3 of 28S and ITS1 rRNA and COI gene sequences indicated that the Maryland and California populations belong to the same species, described herein as L. patuxentensis n. sp.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"16 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135391843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Summary Accurate measurements of soil nematode communities are important for an in-depth understanding of the ecological functions of soil nematodes. High throughput sequencing (HTS) has been reported extensively, but the concordance between HTS and morphological identification results is still lacking. To compare two methods, we selected bare patches (BP), short-term recovery patches (SP), middle-term recovery patches (MP) and long-term recovery patches (LP) of different restoration succession stages in three sample sites to survey the nematode characteristics. In addition to nematode community structure and community ecological function, common nematode genera in BP, SP, MP and LP were compared by two methods: HTS and morphological identification. The results show that the number of species identified in the morphological analysis was lower than using HTS. The soil nematode diversity in different recovery patches was LP > MP > SP > BP. The indices of Shannon-Wiener, Pielou, Simpson and species number of different recovery patches based on HTS reflected the biodiversity of nematode communities, which was consistent with the results of morphological identification. Of the common nematode genera, Coslenchus , Aphelenchus and Leptonchus showed a significant correlation by the two methods. Although both methods have limitations, the HTS provides a more effective means of observing soil nematode biodiversity levels for rapid insight across recovery patches in degraded alpine meadows of the Yellow River source region in our results.
{"title":"Variability in soil nematode communities across recovery patches in degraded Alpine meadows of the Yellow River source region","authors":"Guorong Chen, Jing Hu, Chengyi Li, Yandi She, Yong Wu, Xilai Li","doi":"10.1163/15685411-bja10293","DOIUrl":"https://doi.org/10.1163/15685411-bja10293","url":null,"abstract":"Summary Accurate measurements of soil nematode communities are important for an in-depth understanding of the ecological functions of soil nematodes. High throughput sequencing (HTS) has been reported extensively, but the concordance between HTS and morphological identification results is still lacking. To compare two methods, we selected bare patches (BP), short-term recovery patches (SP), middle-term recovery patches (MP) and long-term recovery patches (LP) of different restoration succession stages in three sample sites to survey the nematode characteristics. In addition to nematode community structure and community ecological function, common nematode genera in BP, SP, MP and LP were compared by two methods: HTS and morphological identification. The results show that the number of species identified in the morphological analysis was lower than using HTS. The soil nematode diversity in different recovery patches was LP > MP > SP > BP. The indices of Shannon-Wiener, Pielou, Simpson and species number of different recovery patches based on HTS reflected the biodiversity of nematode communities, which was consistent with the results of morphological identification. Of the common nematode genera, Coslenchus , Aphelenchus and Leptonchus showed a significant correlation by the two methods. Although both methods have limitations, the HTS provides a more effective means of observing soil nematode biodiversity levels for rapid insight across recovery patches in degraded alpine meadows of the Yellow River source region in our results.","PeriodicalId":18928,"journal":{"name":"Nematology","volume":"40 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135680069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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