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Pearce TL, Scott JB, Wilson CR, Gent DH. Evolution of the Genetic Structure of the Didymella tanaceti Population During Development of Succinate Dehydrogenase Inhibitor Resistance. Phytopathology 2023; 113:1946-1958. [PMID: 37129263 DOI: 10.1094/phyto-10-22-0385-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 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] [Indexed: 05/03/2023]
Abstract
Emergence of pathogens with decreased sensitivity to succinate dehydrogenase inhibitor fungicides is a global agronomical issue. Analysis of Didymella tanaceti isolates (n = 173), which cause tan spot of pyrethrum (Tanacetum cinerariifolium), collected prior to (2004 to 2005) and after (2009, 2010, 2012, and 2014) the commercial implementation of boscalid in Tasmanian pyrethrum fields identified that insensitivity developed over time and has become widespread. To evaluate temporal change, isolates were characterized for frequency of mutations in the succinate dehydrogenase (Sdh) B, C, and D subunits associated with boscalid resistance, mating type, and SSR genotype. All isolates from 2004 and 2005 exhibited wild-type (WT) Sdh alleles. Seven known Sdh substitutions were identified in isolates collected from 2009 to 2014. In 2009, 60.7% had Sdh substitutions associated with boscalid resistance in D. tanaceti. The frequency of WT isolates decreased over time, with no WT isolates identified in 2014. The frequency of the SdhB-H277Y genotype increased from 10.7 to 77.8% between 2009 and 2014. Genotypic evidence suggested that a shift in the population structure occurred between 2005 and 2009, with decreases in gene diversity (uh; 0.51 to 0.34), genotypic evenness (E5; 0.96 to 0.67), genotypic diversity (G; 9.3 to 6.8), and allele frequencies. No evidence was obtained to support the rapid spread of Sdh genotypes by clonal expansion of the population. Thus, insensitivity to boscalid has developed and become widespread within a diverse population within 4 years of usage. These results suggest that D. tanaceti can disperse insensitivity through repeated frequent mutation, sexual recombination, or a combination of both.
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Affiliation(s)
- Tamieka L Pearce
- Tasmanian Institute of Agriculture, College of Sciences and Engineering, University of Tasmania, Burnie, Tasmania 7320, Australia
| | - Jason B Scott
- Tasmanian Institute of Agriculture, College of Sciences and Engineering, University of Tasmania, Burnie, Tasmania 7320, Australia
| | - Calum R Wilson
- Tasmanian Institute of Agriculture, University of Tasmania, Sandy Bay, Tasmania 7005
| | - David H Gent
- U.S. Department of Agriculture-Agriculture Research Service, Forage Seed and Cereal Research Unit, Corvallis, OR 97331
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Liu Y, Vaghefi N, Ades PK, Idnurm A, Ahmed A, Taylor PWJ. Globisporangium and Pythium Species Associated with Yield Decline of Pyrethrum ( Tanacetum cinerariifolium) in Australia. Plants (Basel) 2023; 12:1361. [PMID: 36987047 PMCID: PMC10051369 DOI: 10.3390/plants12061361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Pyrethrum (Tanacetum cinerariifolium) cultivation in Australia, which accounts for the majority of global production of natural insecticidal pyrethrins, is affected by a persistent yield decline which in part is caused by a complex of pathogens. Globisporangium and Pythium species were isolated from crown and roots of pyrethrum plants showing stunting and brown discoloration of crown tissue, and from soil adjacent to diseased plants from yield-decline-affected sites in Tasmania and Victoria, Australia. Ten known Globisporangium species (Globisporangium attrantheridium, G. erinaceum, G. intermedium, G. irregulare, G. macrosporum, G. recalcitrans, G. rostratifingens, G. sylvaticum, G. terrestris and G. ultimum var. ultimum), two new Globisporangium species (Globisporangium capense sp. nov. and Globisporangium commune sp. nov.) and three Pythium species (Pythium diclinum/lutarium, P. tracheiphilum and P. vanterpoolii) were identified through morphological studies and multigene phylogenetic analyses using ITS and Cox1 sequences. Globisporangium ultimum var. ultimum, G. sylvaticum, G. commune sp. nov. and G. irregulare were most abundant. Globisporangium attrantheridium, G. macrosporum and G. terrestris were reported for the first time in Australia. Seven Globisporangium species were pathogenic on both pyrethrum seeds (in vitro assays) and seedlings (glasshouse bioassays), while two Globisporangium species and three Pythium species only caused significant symptoms on pyrethrum seeds. Globisporangium irregulare and G. ultimum var. ultimum were the most aggressive species, causing pyrethrum seed rot, seedling damping-off and significant plant biomass reduction. This is the first report of Globisporangium and Pythium species causing disease in pyrethrum globally and suggests that oomycete species in the family Pythiaceae may have an important role in the yield decline of pyrethrum in Australia.
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Affiliation(s)
- Yuzhu Liu
- School of Agriculture and Food, Faculty of Science, University of Melbourne, Parkville, VIC 3010, Australia
| | - Niloofar Vaghefi
- School of Agriculture and Food, Faculty of Science, University of Melbourne, Parkville, VIC 3010, Australia
| | - Peter K. Ades
- School of Ecosystem and Forest Sciences, Faculty of Science, University of Melbourne, Parkville, VIC 3010, Australia
| | - Alexander Idnurm
- School of BioSciences, Faculty of Science, University of Melbourne, Parkville, VIC 3010, Australia
| | - Aabroo Ahmed
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N2R6, Canada
| | - Paul W. J. Taylor
- School of Agriculture and Food, Faculty of Science, University of Melbourne, Parkville, VIC 3010, Australia
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Vaglica A, Peri E, Badalamenti N, Ilardi V, Bruno M, Guarino S. Chemical Composition and Evaluation of Insecticidal Activity of Seseli bocconei Essential Oils against Stored Products Pests. Plants (Basel) 2022; 11:3047. [PMID: 36432776 PMCID: PMC9697863 DOI: 10.3390/plants11223047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 06/16/2023]
Abstract
In this study, the chemical composition of the essential oils (EOs) obtained from different aerial parts (flowers, leaves, and stems) of Seseli bocconei Guss., a wild species endemic of Sicily, was investigated. Furthermore, the EOs' biocidal effects towards two pests of stored products, Sitophilus oryzae and Callosobruchus maculates, were evaluated. This activity was evaluated in Petri dish bioassays to establish the survival rate of adults treated with the EOs comparing them with solvent and a commonly used insecticide (pyrethrum). The data obtained from the toxicity bioassay evidenced that stems' EOs and leaves' EOs have a contact/fumigation effect towards the two insect species tested, while the EOs from the flowers did not exhibit a different mortality than the solvent. The EOs from the stem and leaves of S. bocconei, tested at 10 mg/petri dish, determined a LT50 of 53.38 and 42.97 h, respectively, on S. oryzae adults, and of 45.23 and 42.97 h, respectively, on C. maculatus adults. The promising bioactivity of S. bocconei leaves' EOs and stems' EOs toward S. oryzae and C. maculatus is encouraging in the perspective to test these oils and their main constituents for further experiments in the laboratory and field.
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Affiliation(s)
- Alessandro Vaglica
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Ezio Peri
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, Viale delle Scienze, Building 5, 90128 Palermo, Italy
| | - Natale Badalamenti
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Vincenzo Ilardi
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Maurizio Bruno
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
- Centro Interdipartimentale di Ricerca “Riutilizzo Bio-Based Degli Scarti da Matrici Agroalimentari” (RIVIVE), Università di Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Salvatore Guarino
- Institute of Biosciences and Bioresources (IBBR), National Research Council of Italy (CNR), Corso Calatafimi 414, 90129 Palermo, Italy
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Yan R, Zhou Q, Xu Z, Wu Y, Zhu G, Wang M, Guo Y, Dong K, Chen M. Pyrethrins elicit olfactory response and spatial repellency in Aedes albopictus. Pest Manag Sci 2021; 77:3706-3712. [PMID: 33798266 DOI: 10.1002/ps.6390] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/08/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Pyrethrum from dry flowers of Chrysanthemum is a well-known botanical insecticide and repellent. Its insecticidal activity attributes to its six insecticidal esters, collectively known as pyrethrins. Pyrethrins and its synthetic analogs pyrethroids exert their toxic action by modifying the function of voltage-gated sodium channels. Aside from insecticidal activity, pyrethrum has also been used to repel mosquitoes for centuries. Today, pyrethrum continues to be used as an active ingredient in mosquito coils and other mosquito-repellent devices globally. However, the mechanism of pyrethrum repellency remains largely unknown. RESULTS Here we report that pyrethrum vapor induced spatial (non-contact) repellency in Aedes albopictus, a major vector of dengue and West Nile viruses. Using electroantennogram (EAG) recordings from adult antennae, we found that pyrethrum elicited EAG response in a dose-dependent manner. We then isolated the six insecticidal esters, pyrethrins I and II, cinerins I and II, jasmolins I and II from pyrethrum extract and discovered that five of the six esters, except jasmolin I, all elicited EAG responses. Furthermore, pyrethrins I and II, cinerin II and jasmolin II induced repellency, whereas cinerin I and jasmolin I did not. CONCLUSION Of the six pyrethrins, four of them, pyrethrins I and II, cinerin II and jasmolin II, activate olfactory-receptor neurons and elicit spatial repellency in Ae. albopictus. Our study provided a foundation for future structure-function studies of pyrethrins, their cognate olfactory receptors and efficacies of repellency and for the development of new and more effective mosquito repellents for controlling vector-borne human diseases. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Ru Yan
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Qiaoling Zhou
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Zhanyi Xu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Yuyan Wu
- Institute for Communicable Disease Control and Prevention, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Guonian Zhu
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Mengcen Wang
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Yirong Guo
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Ke Dong
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, MI, USA
- Department of Biology, Duke University, Durham, NC, USA
| | - Mengli Chen
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
- College of Agricultural and Food Sciences, Zhejiang A&F University, Hangzhou, China
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Fernández-Grandon GM, Harte SJ, Ewany J, Bray D, Stevenson PC. Additive Effect of Botanical Insecticide and Entomopathogenic Fungi on Pest Mortality and the Behavioral Response of Its Natural Enemy. Plants (Basel) 2020; 9:plants9020173. [PMID: 32024119 PMCID: PMC7076379 DOI: 10.3390/plants9020173] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 11/16/2022]
Abstract
Sustainable agricultural intensification employs alternatives to synthetic insecticides for pest management, but these are not always a direct replacement. Botanical insecticides, for example, have rapid knockdown but are highly labile and while biological pesticides are more persistent, they are slow acting. To mitigate these shortcomings, we combined the entomopathogenic fungus (EPF) Metarhizium anisopliae with pyrethrum and evaluated their efficacy against the bean aphid, Aphis fabae. To ascertain higher trophic effects, we presented these treatments to the parasitoid, Aphidius colemani, on an aphid infested plant in a Y-tube olfactometer and measured their preferences. Aphid mortality was significantly higher than controls when exposed to EPF or pyrethrum but was greater still when exposed to a combination of both treatments, indicating an additive effect. This highlights the potential for applications of pyrethrum at lower doses, or the use of less refined products with lower production costs to achieve control. While parasitoids were deterred by aphid infested plants treated with EPF, no preference was observed with the combination pesticide, which provides insight into the importance that both application technique and timing may play in the success of this new technology. These results indicate the potential for biorational pesticides that combine botanicals with EPF.
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Affiliation(s)
| | - Steven J Harte
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Jaspher Ewany
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Daniel Bray
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Philip C Stevenson
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
- Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
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Fernández-Grandon GM, Harte SJ, Ewany J, Bray D, Stevenson PC. Additive Effect of Botanical Insecticide and Entomopathogenic Fungi on Pest Mortality and the Behavioral Response of Its Natural Enemy. Plants (Basel) 2020. [PMID: 32024119 DOI: 10.3390/plants9020173www.mdpi.com/journal/plants] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Sustainable agricultural intensification employs alternatives to synthetic insecticides for pest management, but these are not always a direct replacement. Botanical insecticides, for example, have rapid knockdown but are highly labile and while biological pesticides are more persistent, they are slow acting. To mitigate these shortcomings, we combined the entomopathogenic fungus (EPF) Metarhizium anisopliae with pyrethrum and evaluated their efficacy against the bean aphid, Aphis fabae. To ascertain higher trophic effects, we presented these treatments to the parasitoid, Aphidius colemani, on an aphid infested plant in a Y-tube olfactometer and measured their preferences. Aphid mortality was significantly higher than controls when exposed to EPF or pyrethrum but was greater still when exposed to a combination of both treatments, indicating an additive effect. This highlights the potential for applications of pyrethrum at lower doses, or the use of less refined products with lower production costs to achieve control. While parasitoids were deterred by aphid infested plants treated with EPF, no preference was observed with the combination pesticide, which provides insight into the importance that both application technique and timing may play in the success of this new technology. These results indicate the potential for biorational pesticides that combine botanicals with EPF.
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Affiliation(s)
| | - Steven J Harte
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Jaspher Ewany
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Daniel Bray
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | - Philip C Stevenson
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
- Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK
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Abstract
Academic interest in plant natural products with insecticidal properties has continued to grow in the past 20 years, while commercialization of new botanical insecticides and market expansion of existing botanicals has lagged considerably behind. Insecticides based on pyrethrum and neem (azadirachtin) continue to be standard bearers in this class of pesticides, but globally, their increased presence is largely a consequence of introduction into new jurisdictions. Insecticides based on plant essential oils are just beginning to emerge as useful plant protectants. Some countries (such as Turkey, Uruguay, the United Arab Emirates, and Australia) have relaxed regulatory requirements for specific plant extracts and oils, while in North America and the European Union, stricter requirements have slowed progress toward commercialization of new products. Botanicals are likely to remain niche products in many agricultural regions and may have the greatest impact in developing countries in tropical regions where the source plants are readily available and conventional products are both expensive and dangerous to users.
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Affiliation(s)
- Murray B Isman
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada;
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Lelwala RV, Scott JB, Ades PK, Taylor PWJ. Population Structure of Colletotrichum tanaceti in Australian Pyrethrum Reveals High Evolutionary Potential. Phytopathology 2019; 109:1779-1792. [PMID: 31179858 DOI: 10.1094/phyto-03-19-0091-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Colletotrichum tanaceti, the causal agent of anthracnose, is an emerging pathogen of commercially grown pyrethrum (Tanacetum cinerariifolium) in Australia. A microsatellite marker library was developed to understand the spatio-genetic structure over three sampled years and across two regions where pyrethrum is cultivated in Australia. Results indicated that C. tanaceti was highly diverse with a mixed reproductive mode; comprising both sexual and clonal reproduction. Sexual reproduction of C. tanaceti was more prevalent in Tasmania than in Victoria. Little differentiation was observed among field populations likely due to isolation by colonization but most of the genetic variation was occurring within populations. C. tanaceti was likely to have had a long-distance gene and genotype flow among distant populations within a state and between states. Anthropogenic transmission of propagules and wind dispersal of ascospores are the most probable mechanisms of long-distance dispersal of C. tanaceti. Evaluation of putative population histories suggested that C. tanaceti most likely originated in Tasmania and expanded from an unidentified host onto pyrethrum. Victoria was later invaded by the Tasmanian population. With the mixed mode of reproduction and possible long-distance gene flow, C. tanaceti is likely to have a high evolutionary potential and thereby has ability to adapt to management practices in the future.
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Affiliation(s)
- Ruvini V Lelwala
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia 3010
| | - Jason B Scott
- Tasmanian Institute of Agriculture, University of Tasmania, Burnie, Tasmania, Australia 7320
| | - Peter K Ades
- School of Ecosystem and Forest Sciences, University of Melbourne, Victoria, Australia 3010
| | - Paul W J Taylor
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia 3010
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Freemont JA, Littler SW, Hutt OE, Mauger S, Meyer AG, Winkler DA, Kerr MG, Ryan JH, Cole HF, Duggan PJ. Molecular Markers for Pyrethrin Autoxidation in Stored Pyrethrum Crop: Analysis and Structure Determination. J Agric Food Chem 2016; 64:7134-41. [PMID: 27599033 DOI: 10.1021/acs.jafc.6b02959] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Pyrethrum is a natural insecticide extracted from Tanacetum cinerariifolium. Six esters, the pyrethrins, are responsible for the extract's insecticidal activity. The oxidative degradation of pyrethrins through contact with aerial oxygen is a potential cause of pyrethrin losses during pyrethrum manufacture. Described here is the first investigation of the autoxidation chemistry of the six pyrethrin esters isolated from pyrethrum. It was found that pyrethrins I and II, the major pyrethrin esters present in pyrethrum, undergo autoxidation more readily than the minor pyrethrin esters, the jasmolins and cinerins. Chromatographic analysis of pyrethrin I and II autoxidation mixtures showed some correlation with a similar analysis performed on extracts from T. cinerariifolium crop, which had been stored for 12 weeks without added antioxidants. Two pyrethrin II autoxidation products were isolated, characterized, and shown to be present in extracts of stored T. cinerariifolium crop, confirming that autoxidation of pyrethrin esters does occur during crop storage.
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Affiliation(s)
- Jamie A Freemont
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
| | - Stuart W Littler
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
| | - Oliver E Hutt
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
| | - Stephanie Mauger
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
- Institut de Recherche de Chimie Paris, CNRS - Chimie ParisTech , 11 rue Pierre et Marie Curie, 75005 Paris, France
| | - Adam G Meyer
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
| | - David A Winkler
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
- School of Chemical and Physical Sciences, Flinders University , Adelaide, South Australia 5042, Australia
| | - Maurice G Kerr
- Botanical Resources Australia , 44-46 Industrial Drive, Ulverstone, Tasmania 7315, Australia
| | - John H Ryan
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
| | - Helen F Cole
- Botanical Resources Australia , 44-46 Industrial Drive, Ulverstone, Tasmania 7315, Australia
| | - Peter J Duggan
- CSIRO Manufacturing, Bag 10, Clayton South, Victoria 3169, Australia
- School of Chemical and Physical Sciences, Flinders University , Adelaide, South Australia 5042, Australia
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Ogallo JL, McClure MA. Induced Resistance to Meloidogyne hapla by other Meloidogyne species on Tomato and Pyrethrum Plants. J Nematol 1995; 27:441-447. [PMID: 19277310 PMCID: PMC2619633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Advance inoculation of the tomato cv. Celebrity or the pyrethrum clone 223 with host-incompatible Meloidogyne incognita or M. javanica elicited induced resistance to host-compatible M. hapla in pot and field experiments. Induced resistance increased with the length of the time between inoculations and with the population density of the induction inoculum. Optimum interval before challenge inoculation, or population density of inoculum for inducing resistance, was 10 days, or 5,000 infective nematodes per 500-cm(3) pot. The induced resistance suppressed population increase of M. hapla by 84% on potted tomato, 72% on potted pyrethrum, and 55% on field-grown pyrethrum seedlings, relative to unprotected treatments. Pyrethrum seedlings inoculated with M. javanica 10 days before infection with M. hapla were not stunted, whereas those that did not receive the advance inoculum were stunted 33% in pots and 36% in field plots. The results indicated that advance infection of plants with incompatible or mildly virulent nematode species induced resistance to normally compatible nematodes and that the induced resistance response may have potential as a biological control method for plant nematodes.
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