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Meza P, Elgueta S, Sagredo B. Evaluation of fluopyram for management of Meloidogyne ethiopica and migratory nematodes in commercial tomato greenhouses in the Metropolitan Region of Chile. Pest Manag Sci 2021; 77:2863-2869. [PMID: 33554438 DOI: 10.1002/ps.6322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 02/03/2021] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND The nematicidal effects of fluopyram were evaluated for the suppression of Meloidogyne ethiopica and migratory nematodes, Xiphinema americanum s. l., Hemicycliophora spp. and Pratylenchus spp., in two commercial tomato greenhouses in Chile. The effects of fluopyram on plant-parasitic nematodes, plant vigor and fruit yield were determined. RESULTS Fluopyram demonstrated good potential for the management of M. ethiopica and migratory nematodes, especially during the early stages of evaluation (30-60 days after planting). There were also improvements in vigor of treated plants. A general trend in improved fruit quality was also observed, however, no significant differences in total yield were found between treatments. CONCLUSIONS Our study is one of the first evaluations of fluopyram under field conditions against M. ethiopica. The findings suggest that this new nematicide has good potential for the management of M. ethiopica and some migratory nematodes in tomatoes cropped in greenhouses in the Metropolitan Region of Chile. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Pablo Meza
- Laboratory of Nematology, Instituto de Investigaciones Agropecuarias, INIA Centro Regional La Platina, Santiago, Chile
| | - Sebastián Elgueta
- Laboratory of Pesticide Residues and Environment, Instituto de Investigaciones Agropecuarias, INIA Centro Regional La Platina, Santiago, Chile
| | - Boris Sagredo
- Laboratory of Genomic and Biotechnology, Instituto de Investigaciones Agropecuarias, INIA Centro Regional Rayentué, Rengo, Chile
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Wang L, Cheng W, Meng J, Speakmon M, Qiu J, Pillai S, Zhu-Salzman K. Hypoxic environment protects cowpea bruchid (Callosobruchus maculatus) from electron beam irradiation damage. Pest Manag Sci 2019; 75:726-735. [PMID: 30101505 DOI: 10.1002/ps.5172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/29/2018] [Accepted: 08/08/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Electron beam (eBeam) irradiation and hermetic storage are safe and effective technologies to protect stored products. Although hypoxic environment improves performance of some irradiated insects, whether hypoxia affects irradiation of storage insects and impacts pest control efficacy remains to be investigated. RESULTS Using cowpea bruchid (Callosobruchus maculatus) larvae, we showed that, relative to eBeam irradiation under normoxia, the adult emergence rate increased substantially if they were exposed to hypoxia prior to and during eBeam treatment. Conversely, exposure to hypoxia only after eBeam irradiation did not have this protective effect. eBeam irradiation caused an increase in reactive oxygen species (ROS) in normoxic larvae but not in hypoxic larvae. The activity of citrate synthase, a pace-making enzyme in the citric acid cycle, was suppressed under hypoxia but resumed normal function within hours of reoxygenation, suggesting that reduced mitochondrial activity, and thus less ROS production under hypoxia increased insect tolerance to irradiation. Furthermore, reoxygenation accelerated eBeam-induced glutathione-S-transferase activation and potentiated eBeam-enhanced catalase activities. Faster and stronger detoxification capacity in eBeam-irradiated, hypoxic larvae may have protected them from oxidative damage. CONCLUSION Hypoxic environment enhanced radiotolerance of bruchid larvae, presumably due to limited ROS production and elevated antioxidant enzymatic activities after reoxygenation. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Lei Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, USA
| | - Weining Cheng
- Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture, Northwest A&F University, Yangling, People's Republic of China
| | - Jia Meng
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, USA
- College of Plant Protection, Fujian Agricultural and Forest University, Fuzhou, People's Republic of China
| | - Mickey Speakmon
- National Center for Electron Beam Research, Texas A&M University, College Station, TX, USA
| | - Jiangping Qiu
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Suresh Pillai
- National Center for Electron Beam Research, Texas A&M University, College Station, TX, USA
| | - Keyan Zhu-Salzman
- Department of Entomology, Texas A&M University, College Station, TX, USA
- Institute for Plant Genomics & Biotechnology, Texas A&M University, College Station, TX, USA
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Zhang D, Ji X, Meng Z, Qi W, Qiao K. Effects of fumigation with 1,3-dichloropropene on soil enzyme activities and microbial communities in continuous-cropping soil. Ecotoxicol Environ Saf 2019; 169:730-736. [PMID: 30502523 DOI: 10.1016/j.ecoenv.2018.11.071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/16/2018] [Accepted: 11/16/2018] [Indexed: 06/09/2023]
Abstract
The compound 1,3-D (1,3-dichloropropene) is a potential candidate soil fumigant due to the restrictions on methyl bromide (MB). To date, little is known about the soil microbial community changes induced by 1,3-D fumigation. Therefore, soil properties, related soil enzymes, genes encoding the key enzymes of ammonia oxidation in both ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) and bacterial diversity were investigated to assess the effects of 1,3-D fumigation on the soil microbial community. The results exhibited that fumigation with 1,3-D caused accumulation of NH4+-N, but it led to decrease in the rate of NO3--N, and the concentration of NO3--N gradually recovered. At 12 weeks after transplant (WAT) of tomato seedlings, the concentration of NH4+-N and NO3--N were not statistically significant between the 1,3-D treatment groups and the untreated control group. A similar tendency was found for organic matter, soil pH, urease and protease activities. Moreover, quantitative real-time PCR (qPCR) showed that 1,3-D decreased total bacterial abundance, AOA-amoA and AOB-amoA genes. In addition, Illumina MiSeq sequencing analysis revealed that soil bacterial community diversities were significantly reduced at earlier sampling time points, and at later sampling time points, soil bacterial diversity gradually recovered, there was no significant difference compared to the control group. The present study provides useful information to evaluate the environmental safety of 1,3-D.
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Affiliation(s)
- Dianli Zhang
- Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, People's Republic of China
| | - Xiaoxue Ji
- Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, People's Republic of China
| | - Zhen Meng
- Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, People's Republic of China
| | - Wenzhe Qi
- Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, People's Republic of China
| | - Kang Qiao
- Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, People's Republic of China.
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Xu S, Yang N, Zheng S, Yan F, Jiang C, Yu Y, Guo J, Chai Y, Chen Y. The spo0A-sinI-sinR Regulatory Circuit Plays an Essential Role in Biofilm Formation, Nematicidal Activities, and Plant Protection in Bacillus cereus AR156. Mol Plant Microbe Interact 2017; 30:603-619. [PMID: 28430084 DOI: 10.1094/mpmi-02-17-0042-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The rhizosphere bacterium Bacillus cereus AR156 is capable of forming biofilms, killing nematodes, and protecting plants. However, the underlying molecular mechanisms of these processes are not well understood. In this study, we found that the isogenic mutants ΔBcspo0A and ΔBcsinI have significantly reduced colonization and nematicidal activity in vitro and biological control efficacy on the tomato plant under greenhouse conditions. We further investigated the role of the spo0A-sinI-sinR regulatory circuit in biofilm formation, killing against nematodes, and biological control in AR156. Results from mutagenesis of those regulatory genes in AR156 and their heterologous expression in B. subtilis suggested that the spo0A-sinI-sinR genetic circuit is not only essential for biofilm formation and cell differentiation in AR156 but also able to functionally replace their counterparts in B. subtilis in a nearly indistinguishable fashion. Genome-wide transcriptional profiling in the wild type and the ΔBcspo0A and ΔBcsinI mutants further revealed hundreds of differentially expressed genes, likely positively regulated by both Spo0A and SinI (via SinR) in AR156. Among them, 29 genes are predicted to be directly controlled by SinR, whose counterpart in B. subtilis is a biofilm master repressor. Collectively, our studies demonstrated the essential role of the spo0A-sinI-sinR regulatory circuit in biofilm formation, cell differentiation, and bacteria-host interactions in B. cereus AR156.
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Affiliation(s)
- Sunde Xu
- 1 Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Nan Yang
- 1 Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Shiyu Zheng
- 1 Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Fang Yan
- 2 Department of Biology, Northeastern University, Boston 02115, U.S.A.; and
- 3 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Chunhao Jiang
- 3 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiyang Yu
- 2 Department of Biology, Northeastern University, Boston 02115, U.S.A.; and
- 3 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Jianhua Guo
- 3 Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yunrong Chai
- 2 Department of Biology, Northeastern University, Boston 02115, U.S.A.; and
| | - Yun Chen
- 1 Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
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Al-Hazmi AS, Dawabah AA, Al-Nadhari SN, Al-Yahya FA. Comparative efficacy of different approaches to managing Meloidogyne incognita on green bean. Saudi J Biol Sci 2017; 24:149-154. [PMID: 28053585 PMCID: PMC5198980 DOI: 10.1016/j.sjbs.2016.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 05/14/2016] [Accepted: 05/16/2016] [Indexed: 11/17/2022] Open
Abstract
A greenhouse study was conducted to compare the relative efficacy of different approaches to managing Meloidogyne incognita on green bean. These approaches included chemical (fumigant, non-fumigant, seed dressing, and seed dip), biological (the egg-parasitic fungus, Paecilomyces lilacinus and the mycorrhizal fungus Glomus sp.), physical (soil solarization), and cultural (chicken litter and urea) methods. Accordingly, nine different control materials and application methods plus nematode-infected and non-infected controls were compared. Two important parameters were considered: plant response (plant growth and root galling) and nematode reproduction (production of eggs and the reproduction factor Rf). The results showed that the use of chicken litter as an organic fertilizer severely affected the growth and survival of the plants. Therefore, this treatment was removed from the evaluation test. All of the other eight treatments were found to be effective against nematode reproduction, but with different levels of efficacy. The eight treatments decreased (38.9–99.8%) root galling, increased plant growth and suppressed nematode reproduction. Based on three important criteria, namely, gall index (GI), egg mass index (EMI), and nematode reproduction factor (RF), the tested materials and methods were categorized into three groups according to their relative control efficacy under the applied test conditions. The three groups were as follows: (1) the relatively high effective group (GI = 1.0–1.4, Rf = 0.07–0.01), which included the fumigant dazomet, the non-fumigant fenamiphos, soil solarization, and seed dip with fenamiphos; (2) the relatively moderate effective group (GI = 3.4–4.0, Rf = 0.24–0.60), which included seed dressing with fenamiphos and urea; and (3) the relatively less effective group (GI = 5.0, Rf = 32.2–37.2), which included P. lilacinus and Glomus sp.
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Cheng X, Liu X, Wang H, Ji X, Wang K, Wei M, Qiao K. Effect of Emamectin Benzoate on Root-Knot Nematodes and Tomato Yield. PLoS One 2015; 10:e0141235. [PMID: 26509680 PMCID: PMC4624971 DOI: 10.1371/journal.pone.0141235] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/05/2015] [Indexed: 11/18/2022] Open
Abstract
Southern root-knot nematode (Meloidogyne incognita) is an obligate, sedentary endoparasite of more than 3000 plant species, that causes heavy economic losses and limit the development of protected agriculture of China. As a biological pesticide, emamectin benzoate has effectively prevented lepidopteran pests; however, its efficacy to control M. incognita remains unknown. The purpose of the present study was to test soil application of emamectin benzoate for management of M. incognita in laboratory, greenhouse and field trials. Laboratory results showed that emamectin benzoate exhibited high toxicity to M. incognita, with LC50 and LC90 values 3.59 and 18.20 mg L(-1), respectively. In greenhouse tests, emamectin benzoate soil application offered good efficacy against M. incognita while maintaining excellent plant growth. In field trials, emamectin benzoate provided control efficacy against M. incognita and resulted in increased tomato yields. Compared with the untreated control, there was a 36.5% to 81.3% yield increase obtained from all treatments and the highest yield was received from the highest rate of emamectin benzoate. The results confirmed that emamectin benzoate has enormous potential for the control of M. incognita in tomato production in China.
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Affiliation(s)
- Xingkai Cheng
- College of Plant Protection, Shandong Agricultural University, Tai’an, Shandong People’s Republic of China
| | - Xiumei Liu
- College of Plant Protection, Shandong Agricultural University, Tai’an, Shandong People’s Republic of China
| | - Hongyan Wang
- Cotton Research Center, Shandong Academy of Agricultural Sciences, Jinan, Shandong, People’s Republic of China
| | - Xiaoxue Ji
- Plant Protection and Inspection Station of Feicheng, Feicheng, Shandong, People’s Republic of China
| | - Kaiyun Wang
- College of Plant Protection, Shandong Agricultural University, Tai’an, Shandong People’s Republic of China
| | - Min Wei
- College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an, Shandong, People’s Republic of China
| | - Kang Qiao
- College of Plant Protection, Shandong Agricultural University, Tai’an, Shandong People’s Republic of China
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Qiao K, Liu X, Wang H, Xia X, Ji X, Wang K. Effect of abamectin on root-knot nematodes and tomato yield. Pest Manag Sci 2012; 68:853-857. [PMID: 22395950 DOI: 10.1002/ps.2338] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 09/25/2011] [Accepted: 10/31/2011] [Indexed: 05/27/2023]
Abstract
BACKGROUND Tomato growers in Shandong Province, China, commonly face heavy root-knot nematode infestations. Current methods of control include cadusafos and methyl bromide (MeBr), but alternative methods are required because of the high toxicity of these pesticides and the ecological risk of their use. Therefore, abamectin soil applications were evaluated for their potential to control soil nematodes in a series of laboratory tests, greenhouse pot experiments and field trials. RESULTS Laboratory tests showed that abamectin exhibited rapid knockdown of Meloidogyne incognita, with LC(50) and LC(90) values that were superior to those of cadusafos and averaged 7.06 and 21.81 mg L(-1). In the greenhouse pot experiment, soil applications of abamectin provided significant M. incognita control similar to that provided by cadusafos while maintaining excellent plant height and vigour. In the field trials, abamectin exhibited excellent control effects to nematodes while giving a higher tomato yield. There was a 19.3-39.0% yield increase from the various treatments compared with the control, and the best results were obtained from the highest dose of abamectin. CONCLUSION The results of this study demonstrated that abamectin has the potential to be used as an effective alternative to MeBr and cadusafos for nematode control in tomato production in Shandong Province.
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Affiliation(s)
- Kang Qiao
- Department of Plant Protection, Shandong Agricultural University, Tai'an, Shandong, PR China
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Qiao K, Shi X, Wang H, Ji X, Wang K. Managing root-knot nematodes and weeds with 1,3-dichloropropene as an alternative to methyl bromide in cucumber crops in China. J Agric Food Chem 2011; 59:2362-2367. [PMID: 21366311 DOI: 10.1021/jf104553f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
1,3-dichloropropene (1,3-D) was evaluated as a potential alternative for the widely used soil fumigant methyl bromide (MeBr) in cucumber (Cucumis sativus Linn.) crops in China. Six treatments were replicated five times in a randomized complete block design: fumigation with MeBr (400 kg·ha(-1)), three 1,3-D doses (90, 120, and 180 L·ha(-1)), an avermectin dose (7.5 L·ha(-1)), and a nontreated control. Results consistently indicated that MeBr was generally superior to the treatments involving all 1,3-D and avermectin, which in turn were superior to the control, for improving cucumber yield and to control nematode and weed. In two successive seasons, 1,3-D at a dose of 180 L·ha(-1) was as effective as MeBr in increasing plant height, vigor, and yield, as well as showed excellent nematode control efficiency, but it had relatively poor potency to control weeds. The present data support the conclusion that 1,3-D is a promising MeBr alternative for managing nematodes and weeds in cucumber crops and can be used in integrated pest management programs.
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Affiliation(s)
- Kang Qiao
- Department of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, People's Republic of China
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Johnston MJ, McVeigh P, McMaster S, Fleming CC, Maule AG. FMRFamide-like peptides in root knot nematodes and their potential role in nematode physiology. J Helminthol 2010; 84:253-65. [PMID: 19843350 DOI: 10.1017/S0022149X09990630] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
FMRFamide-like peptides (FLPs) are a diverse group of neuropeptides that are expressed abundantly in nematodes. They exert potent physiological effects on locomotory, feeding and reproductive musculature and also act as neuromodulators. However, little is known about the specific expression patterns and functions of individual peptides. The current study employed rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) to characterize flp genes from infective juveniles of the root knot nematodes, Meloidogyne incognita and Meloidogyne minor. The peptides identified from these transcripts are sequelogs of FLPs from the free-living nematode, Caenorhabditis elegans; the genes have therefore been designated as Mi-flp-1, Mi-flp-7, Mi-flp-12, Mm-flp-12 and Mi-flp-14. Mi-flp-1 encodes five FLPs with the common C-terminal moiety, NFLRFamide. Mi-flp-7 encodes two copies of APLDRSALVRFamide and APLDRAAMVRFamide and one copy of APFDRSSMVRFamide. Mi-flp-12 and Mm-flp-12 encode the novel peptide KNNKFEFIRFamide (a longer version of RNKFEFIRFamide found in C. elegans). Mi-flp-14 encodes a single copy of KHEYLRFamide (commonly known as AF2 and regarded as the most abundant nematode FLP), and a single copy of the novel peptide KHEFVRFamide. These FLPs share a high degree of conservation between Meloidogyne species and nematodes from other clades, including those of humans and animals, perhaps suggesting a common neurophysiological role which may be exploited by novel drugs. FLP immunoreactivity was observed for the first time in Meloidogyne, in the circumpharyngeal nerve ring, pharyngeal nerves and ventral nerve cord. Additionally, in situ hybridization revealed Mi-flp-12 expression in an RIR-like neuron and Mi-flp-14 expression in SMB-like neurons, respectively. These localizations imply physiological roles for FLP-12 and FLP-14 peptides, including locomotion and sensory perception.
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Chen Y, Steinberger Y, Cao Z. Effects of Alternatives to Methyl Bromide on Soil Free-Living Nematode Community Dynamics in a Greenhouse Study. ACTA ACUST UNITED AC 2008; 31:95-113. [DOI: 10.1300/j064v31n04_07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mojovic L, Dierksen KP, Upson RH, Caldwell BA, Lawrence JR, Trempy JE, McFadden PN. Blind and na�ve classi?cation of toxicity by fish chromatophores. J Appl Toxicol 2004; 24:355-61. [PMID: 15478185 DOI: 10.1002/jat.1022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cellular and molecular pathways involved in the ability of animals to change color have been studied previously as biosensors and cytosensors of active and toxic agents, but such studies generally have been limited to just a few standardized agents. Here we describe the performance of cultured chromatophore pigment cells from the fin tissue of Siamese fighting fish as sensors of toxic agents under blind sampling conditions at the September 2002 EILATox-Oregon Workshop. Detection was accomplished by monitoring motor protein-mediated movements of cellular pigment in chromatophores at both the gross population level as well as in singly imaged cells. Pigment responses were recorded both during the exposure of chromatophores to each blind sample as well as afterwards when the cells were examined for after-effects by challenging them with clonidine, an adrenergic drug that induces standardized pigment movements. After recording all results and upon breaking the key to reveal the identities of the toxic agents, it was found that all of the toxic samples in the study had been distinguished accurately from non-toxic controls that were included among the blind samples. Furthermore, it was revealed that most of the toxic agents detected had never before been tested or calibrated against chromatophores, demonstrating that detection can be achieved under naive conditions that have not been optimized for the analysis of any particular toxic agent. Finally, by organizing the results into categories of pigment responses, a binary classification tree was generated that distinguished each toxic agent as having a distinct response pattern from the others. Thus, chromatophore-based cytosensors can discover toxicity in the absence of prior knowledge of the agent in question, and the categories of responses of the cells can be used to distinguish one toxic agent from another.
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Affiliation(s)
- Ljiljana Mojovic
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97330, USA
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Tzortzakakis EA, Petsas SE. Investigation of alternatives to methyl bromide for management of Meloidogyne javanica on greenhouse grown tomato. Pest Manag Sci 2003; 59:1311-1320. [PMID: 14667053 DOI: 10.1002/ps.764] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The root galling index and the densities of eggs in roots and juveniles in soil of the root-knot nematode Meloidogyne javanica (Treub) Chitwood on tomato, and the effect of these on crop yield were assessed in greenhouse experiments applying various treatments at two different sites in Crete, Greece. Tomato crops were grown for four cycles by rotating nematode-resistant (first and third spring crops) with susceptible (second and fourth autumn crops) cultivars and receiving the following treatments: (a) untreated control; (b) methyl bromide application before the first and third crops; (c) application of the fungus Pochonia chlamydosporia (Goddard) Zare, Gams & Evans before planting the first, third and fourth crops with a supplementary application three weeks after the beginning of the fourth crop; (d) application of oxamyl in both sites and fenamiphos in site 1 only at the second and fourth crops; (e) combination of treatments (c) and (d). The fungus density in soil was monitored three weeks after application and at the end of each crop, when roots were lifted. Pochonia chlamydosporia had a variable establishment and did not control the nematode. Its pathogenicity on eggs was not demonstrated, as in all cases galls were big, with all egg masses inside and protected from infection. The methyl bromide treatment significantly reduced root galling and egg production compared to other treatments in all crop cycles and the yield of the fourth crop was significantly greater. Nematicides reduced nematode densities compared with untreated controls and the fungus treatment, but they were less effective than methyl bromide and resulted in increased yield in one site only.
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Affiliation(s)
- Emmanuel A Tzortzakakis
- Nematology Laboratory, Plant Protection Institute, National Agricultural Research Foundation, PO BOX 2228, 71003, Heraklion, Crete, Greece.
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