The molecular characterization of Pratylenchus species determined from D2-D3 of 28S rDNA, ITS of rDNA, and COI of mtDNA regions revealed four Pratylenchus species from North Dakota, P. scribneri, P. neglectus, Pratylenchus sp. (ND-2016 isolate HG51), and Pratylenchus sp. (ND-2017). They were clustered in four separate clades in the phylogenetic trees indicating the divergence among species. P. scribneri and Pratylenchus sp. (ND-2016 isolate HG51) were closely associated and Pratylenchus sp. (DH-2017) was closely related to Pratylenchus sp. (ND-2016 isolate HG51). However, P. neglectus was not closely associated with the other three species. Moreover, resistance evaluation of ten corn hybrids to Pratylenchus scribneri, P. neglectus, and Pratylenchus sp. (ND-2017) revealed that 1392 VT2P was moderately resistant to three Pratylenchus species. PFS74K89 and 4913 VT2RIB were moderately resistant to two of the three Pratylenchus species. X5B-8801, DK 43-46, and DKC 44-13 were susceptible to two of the three Pratylenchus species.

Orientador: Jaime Maia dos Santos / Banca: Fernando Eduardo Amado Tersi / Banca: Marineide Mendonça Aguillera / Banca: Antonio Baldo Geraldo Martins / Banca: Modesto Barreto / Resumo: Pratylenchus jaehni é o nematóide mais agressivo na citricultura paulista. A espécie foi descrita em 2001 com base em uma subpopulação coletada em um pomar de Itápolis-SP. Na presente pesquisa foram descritos e documentados os sintomas de plantas de laranjeiras adultas infectadas pelo nematóide, foi mensurada a resistência de seis porta-enxertos, assim como se estudou a faixa de hospedeiros do nematóide em algumas culturas e espécies de plantas daninhas. Em microparcelas, a campo, estudou-se a influência do nematóide, em níveis crescentes de inóculo, sobre o desenvolvimento de plantas jovens de laranjeiras. As plantas infectadas pelo nematóide exibem baixa densidade foliar, folhas e frutos menores, crescimento retardado e, em casos de acentuado déficit hídrico, podem morrer. Nas raízes são observadas manchas necróticas características da infecção e acentuada morte de radicelas. Entre seis portaenxertos estudados o limoeiro 'Cravo' foi o único suscetível ao nematóide, sendo que a tangerina 'Cleópatra', o citrumelo 'Swingle', a tangerina 'Sunki', o Poncirus trifoliata e o citrange 'Carrizo' são resistentes ao nematóide. Entre as culturas estudadas apenas o milheto, a soja, o milho e a Crotalaria juncea são suscetíveis ao nematóide. Aos 12 meses após a inoculação de P. jaehni em plantas jovens de laranjeira 'Valência', enxertadas sobre limoeiro 'Cravo', observaram-se reduções significativas de 22% na altura das plantas, 22,5% no diâmetro do caule, 20,4% no diâmetro da segunda pernada e 43,7% e 52,5% no volume da copa, aos 11 e aos 12 meses, após a inoculação, respectivamente. / Abstract: Pratylenchus jaehni is the most aggressive nematode for the citrus crop in São Paulo State. The species was described in 2001 on the basis of a subpopulation collected in an orchard of Itápolis-SP. In the present research the symptoms of orange plants infected by the nematode were described and documented. Also, the resistance of six rootstocks was evaluated, as well as the host range of the nematode crops and weeds. In microplots, at field conditions, it was studied the influence of the nematode in increasing levels of inoculum on the development of young plants of orange trees. The plants infected by the nematode show low foliar density, small leaves and fruits, smaller rate of growth and, under severe water stress they may die. Necrotic lesions on the roots, characteristic of the infection and death of feeder roots are observed. Among six rootstocks studied Rangpur lime was the only susceptible one to the nematode. Cleopatra tangerine, citrumelo Swingle, Sunki tangerine, Poncirus trifoliata and citrange Carrizo are resistant to the nematode. Among the plants species studied only the millet, soybean, maize and Crotalaria juncea are susceptible to the nematode. After 12 months from the inoculation of P. jaehni in young plants of orange trees 'Valência', grafted on Rangpur lime, it were observed reductions of 22% in the height of the plants, 22.5% in the diameter of the stem, 20.4% in the diameter of the second branch and 43.7% and 52.5% of the canopy volume at 11 and 12 months, respectively, after the inoculation. / Doutor

Four studies were conducted to investigate plant-parasitic nematodes (PPN) of corn and soybean in ND. The first study investigated the incidence and abundance of vermiform PPN in ND corn fields in 2015 and 2016. Samples were collected from 300 corn fields across 20 counties. Seventy-two percent of the fields were positive for PPN. The major genera of PPN identified were Helicotylenchus, Tylenchorhynchus, Paratylenchus, Pratylenchus, Heterodera, Xiphinema, Hoplolaimus, and Paratrichodorus. The second study characterized SCN (SCN; Heterodera glycines) virulence phenotypes in ND. A total of 419 soybean fields across 22 counties were sampled during 2015, 2016, and 2017. Among these samples, 73 SCN field populations were successfully virulence phenotyped using the HG type tests. The HG types that were detected and confirmed in ND were HG type 0, 7, 2.5.7, 5.7, 1.2.5.7, and 2.7. The third study developed a new molecular method for detecting and identifying a new Pratylenchus sp. discovered in a soybean field in ND. A species-specific primer set, that can be used in both conventional and real-time polymerase chain reaction (PCR) assays, was designed from the internal transcribed spacer (ITS) region of ribosomal DNA. Laboratory experiments confirmed that the primers only amplified DNA of the target nematode species but not the non-target species used in the specificity tests. Practically, DNA from as little as a single nematode could be used to specifically identify the new Pratylenchus sp. using the molecular diagnostic methods developed in this study. The fourth study was conducted to ascertain resistance levels of 20 soybean cultivars to the new Pratylenchus sp. Combined results of four trials indicated that seven of the cultivars were moderately resistant, ten were moderately susceptible, four were susceptible, and none of the cultivars tested were resistant. Analysis of the habitat preference of the new Pratylenchus sp., revealed that above or close to 50% of the nematode population resided in roots at nine weeks after planting for a majority of the cultivars evaluated. Results from these studies will be helpful in improving nematode detection and developing management strategies to control plant-parasitic nematodes in ND corn and soybean fields.

Made available in DSpace on 2014-06-11T19:25:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-25Bitstream added on 2014-06-13T18:26:15Z : No. of bitstreams: 1 barbosa_bff_me_jabo.pdf: 705710 bytes, checksum: b580c7d1b1347b4684db02e1630e42ee (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No Brasil, Pratylenchus zeae, Meloidogyne javanica e M. incognita são as espécies-chave para a cana-de-açúcar. Em dois experimentos conduzidos em casa de vegetação, em Jaboticabal, um com duração de 12 meses e outro de 75 dias, foram estudadas as inter-relações de M. incognita, M. javanica e P. brachyurus, envolvendo 10 variedades de cana-de-açúcar. A resistência das variedades variou expressivamente em relação aos nematóides estudados. Conquanto a taxa de multiplicação de M. javanica, na variedade SP911049, tenha sido muito menor que a de M. incognita, os dados sugerem que M. javanica é mais agressiva. O parasitismo de Meloidogyne javanica e M. incognita a ‘SP911049’ predispõe essa variedade ao ataque da cochonilha Saccharicoccus sacchari. As variáveis biométricas utilizadas no presente estudo, a massa de matéria fresca de parte aérea e raízes confirmam maior agressividade de M. javanica à variedade SP911049, em relação a M. incognita. Entre as variedades testadas, a SP891115 é a única resistente à M. incognita e nenhuma delas é resistente a M. javanica. Entre essas, a RB855453 é a menos suscetível a M. javanica, e a SP801816 é a mais suscetível às três espécies de nematóides incluídas no estudo. As variedades CTC2, SP832847, RB855156, SP803280, CTC9, SP911049, SP891115 e RB855453 são resistentes a P. brachyurus, e somente a SP801816, entre as nove variedades testadas, é suscetível, sendo que o nematóide influenciou negativamente nos valores de todas as variáveis consideradas nas avaliações. / In Brazil, Pratylenchus zeae, Meloidogyne javanica and M. Incognita are the key species for sugar cane. In two experiments carried out in pots in a greenhouse in Jaboticabal city, one with duration of 12 months another for 75 days, the relationships of M. incognita, M. javanica and P. brachyurus, involving 10 varieties of sugar cane were studied. The resistance of the varieties varied significantly in relation to the nematodes. While the rate of increase of M. javanica in SP911049 variety has been lower than that of M. incognita, the data suggest that M. javanica is more aggressive. The parasitism of M. javanica and M. incognita to ‘SP911049’ predisposes that variety to attack of Saccharicoccus sacchari. The biometric variables used in this study, the mass of fresh matter of the above ground part and the mass of fresh matter of roots confirm the greater aggressiveness of M. javanica to the variety SP911049, than M. incognita. Among the varieties tested, SP891115 is the only resistant to M. incognita and none of them are resistant to M. javanica. Among these, RB855453 is the least susceptible to M. javanica and SP801816 is the most susceptible to the three species of nematodes included in the study. The varieties CTC2, SP832847, RB855156, SP803280, CTC9, SP911049, SP891115 and RB855453 are resistant to P. brachyurus and only the variety SP801816, among the nine varieties tested is susceptible. Also, the nematode adversely affected the values of all variables considered in the evaluations.

Made available in DSpace on 2014-06-11T19:33:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-27Bitstream added on 2014-06-13T20:25:26Z : No. of bitstreams: 1 barbosa_bff_dr_jabo.pdf: 1978509 bytes, checksum: 4c72b11295f0f3a1d5f49894d1883b90 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Empresa Agrolatino / Pratylenchus zeae, Meloidogyne javanica e M. incognita são nematoides-chave na cana-de-açúcar, no Brasil, mas P. brachyurus também é frequentemente encontrado. Três experimentos foram conduzidos para o estudo. No primeiro, comparou-se a agressividade de P. brachyurus e P. zeae a cultura. No segundo e no terceiro, buscaram-se alternativas de controle. O primeiro e o segundo experimentos foram em vasos de 100 L, a céu aberto e o terceiro em soqueira de quarto a quinto cortes. No primeiro foram inoculados 10, 100, 1.000, 10.000 e 100.000 espécimes/planta, isoladamente. No segundo foram testados Agrolmin® (ácidos húmicos e fúlvicos extraídos de turfa), Agrolmin + Fungos nematófagos (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofurano e Testemunha sem e com nematoides. No terceiro, testaram-se: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0,5 L.m linear-1)], FN (1 L.m linear-1), Formulação de FN (FFN) no Agrolmin Nitro (300 L.ha-1), FFN no Agrolmin Nitro (600 L.ha-1), Carbofurano (6 L.ha-1) e a Testemunha. Nos três experimentos foi avaliada a dinâmica da população das pragas e avaliações biométricas e quantitativas das plantas, ao final. Observou-se que a variedade CTC2 é suscetível à P. zeae e intolerante à P. brachyurus, que foi mais agressivo. Os FN incrementaram a produtividade, principalmente quando associados ao Agrolmin. O parasitismo de H. dihystera reduziu o de M. javanica, mas causou danos à cultura. A FFN no Agrolmin Nitro (300 L.ha-1) reduziu as populações de P. zeae e de M. javanica e elevou a produtividade em 14,6 Mg.ha-1, em relação a testemunha / Pratylenchus zeae, Meloidogyne javanica and M. incognita are the key nematodes in sugar cane in Brazil, but P. brachyurus is also frequently found. Three experiments were conducted. In the first one, the aggressiveness of P. brachyurus and P. zeae to the crop was compared. In the second and third ones alternatives for the control were sought. The first and second experiments were carried out in 100 L pots, in open area and, the third experiment in ratoon of fourth to fifth cropping. In the first one levels of 10, 100, 1,000, 10,000 and 100,000 specimens/plant were inoculated, individually. In the second one it was tested Agrolmin ® (humic and fulvic acids extracted from peat), Agrolmin plus nematophagous fungi (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofuran and the Control with and without nematodes. In the third experiment were tested: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0.5 L.m linear -1)], FN (1 L.m linear-1) Formulation of FN (FFN) in Agrolmin Nitro (300 L.ha-1), FFN in Agrolmin Nitro (600 L.ha-1), Carbofuran (6 L.ha-1) and Control. In the three experiments it was analyzed the population dynamics of the nematodes as well biometric and quantitative assessments of the plants at the end. It was observed that the variety CTC2 is susceptible to P. zeae and intolerant to P. brachyurus which was more aggressive. The FN increased productivity, especially when associated with Agrolmin. The parasitism of H. dihystera reduced M. javanica population, but caused damage to the crop. The FFN in Agrolmin Nitro (300 L.ha-1) reduced populations of P. zeae and M. javanica and increased productivity by 14.6 Mg.ha-1, compared to control

Made available in DSpace on 2014-06-11T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-08-31Bitstream added on 2014-06-13T19:23:50Z : No. of bitstreams: 1 calzavara_sa_dr_jabo.pdf: 571802 bytes, checksum: a2598276a148c9facfc38bedc5ba67f1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Pratylenchus jaehni é o nematóide mais agressivo na citricultura paulista. A espécie foi descrita em 2001 com base em uma subpopulação coletada em um pomar de Itápolis-SP. Na presente pesquisa foram descritos e documentados os sintomas de plantas de laranjeiras adultas infectadas pelo nematóide, foi mensurada a resistência de seis porta-enxertos, assim como se estudou a faixa de hospedeiros do nematóide em algumas culturas e espécies de plantas daninhas. Em microparcelas, a campo, estudou-se a influência do nematóide, em níveis crescentes de inóculo, sobre o desenvolvimento de plantas jovens de laranjeiras. As plantas infectadas pelo nematóide exibem baixa densidade foliar, folhas e frutos menores, crescimento retardado e, em casos de acentuado déficit hídrico, podem morrer. Nas raízes são observadas manchas necróticas características da infecção e acentuada morte de radicelas. Entre seis portaenxertos estudados o limoeiro ‘Cravo’ foi o único suscetível ao nematóide, sendo que a tangerina ‘Cleópatra’, o citrumelo ‘Swingle’, a tangerina ‘Sunki’, o Poncirus trifoliata e o citrange ‘Carrizo‘ são resistentes ao nematóide. Entre as culturas estudadas apenas o milheto, a soja, o milho e a Crotalaria juncea são suscetíveis ao nematóide. Aos 12 meses após a inoculação de P. jaehni em plantas jovens de laranjeira ‘Valência’, enxertadas sobre limoeiro ‘Cravo’, observaram-se reduções significativas de 22% na altura das plantas, 22,5% no diâmetro do caule, 20,4% no diâmetro da segunda pernada e 43,7% e 52,5% no volume da copa, aos 11 e aos 12 meses, após a inoculação, respectivamente. / Pratylenchus jaehni is the most aggressive nematode for the citrus crop in São Paulo State. The species was described in 2001 on the basis of a subpopulation collected in an orchard of Itápolis-SP. In the present research the symptoms of orange plants infected by the nematode were described and documented. Also, the resistance of six rootstocks was evaluated, as well as the host range of the nematode crops and weeds. In microplots, at field conditions, it was studied the influence of the nematode in increasing levels of inoculum on the development of young plants of orange trees. The plants infected by the nematode show low foliar density, small leaves and fruits, smaller rate of growth and, under severe water stress they may die. Necrotic lesions on the roots, characteristic of the infection and death of feeder roots are observed. Among six rootstocks studied Rangpur lime was the only susceptible one to the nematode. Cleopatra tangerine, citrumelo Swingle, Sunki tangerine, Poncirus trifoliata and citrange Carrizo are resistant to the nematode. Among the plants species studied only the millet, soybean, maize and Crotalaria juncea are susceptible to the nematode. After 12 months from the inoculation of P. jaehni in young plants of orange trees `Valência', grafted on Rangpur lime, it were observed reductions of 22% in the height of the plants, 22.5% in the diameter of the stem, 20.4% in the diameter of the second branch and 43.7% and 52.5% of the canopy volume at 11 and 12 months, respectively, after the inoculation.

Orientador: Jaime Maia dos Santos / Banca: Marineide Mendonça Aguillera / Banca: Júlio Cesar Galli / Resumo: No Brasil, Pratylenchus zeae, Meloidogyne javanica e M. incognita são as espécies-chave para a cana-de-açúcar. Em dois experimentos conduzidos em casa de vegetação, em Jaboticabal, um com duração de 12 meses e outro de 75 dias, foram estudadas as inter-relações de M. incognita, M. javanica e P. brachyurus, envolvendo 10 variedades de cana-de-açúcar. A resistência das variedades variou expressivamente em relação aos nematóides estudados. Conquanto a taxa de multiplicação de M. javanica, na variedade SP911049, tenha sido muito menor que a de M. incognita, os dados sugerem que M. javanica é mais agressiva. O parasitismo de Meloidogyne javanica e M. incognita a 'SP911049' predispõe essa variedade ao ataque da cochonilha Saccharicoccus sacchari. As variáveis biométricas utilizadas no presente estudo, a massa de matéria fresca de parte aérea e raízes confirmam maior agressividade de M. javanica à variedade SP911049, em relação a M. incognita. Entre as variedades testadas, a SP891115 é a única resistente à M. incognita e nenhuma delas é resistente a M. javanica. Entre essas, a RB855453 é a menos suscetível a M. javanica, e a SP801816 é a mais suscetível às três espécies de nematóides incluídas no estudo. As variedades CTC2, SP832847, RB855156, SP803280, CTC9, SP911049, SP891115 e RB855453 são resistentes a P. brachyurus, e somente a SP801816, entre as nove variedades testadas, é suscetível, sendo que o nematóide influenciou negativamente nos valores de todas as variáveis consideradas nas avaliações. / Abstract: In Brazil, Pratylenchus zeae, Meloidogyne javanica and M. Incognita are the key species for sugar cane. In two experiments carried out in pots in a greenhouse in Jaboticabal city, one with duration of 12 months another for 75 days, the relationships of M. incognita, M. javanica and P. brachyurus, involving 10 varieties of sugar cane were studied. The resistance of the varieties varied significantly in relation to the nematodes. While the rate of increase of M. javanica in SP911049 variety has been lower than that of M. incognita, the data suggest that M. javanica is more aggressive. The parasitism of M. javanica and M. incognita to 'SP911049' predisposes that variety to attack of Saccharicoccus sacchari. The biometric variables used in this study, the mass of fresh matter of the above ground part and the mass of fresh matter of roots confirm the greater aggressiveness of M. javanica to the variety SP911049, than M. incognita. Among the varieties tested, SP891115 is the only resistant to M. incognita and none of them are resistant to M. javanica. Among these, RB855453 is the least susceptible to M. javanica and SP801816 is the most susceptible to the three species of nematodes included in the study. The varieties CTC2, SP832847, RB855156, SP803280, CTC9, SP911049, SP891115 and RB855453 are resistant to P. brachyurus and only the variety SP801816, among the nine varieties tested is susceptible. Also, the nematode adversely affected the values of all variables considered in the evaluations. / Mestre

Orientador: Pedro Luiz Martins Soares / Banca: Marineide Mendonça Aguillera / Banca: Elvira Maria Regis Pedrosa / Banca: Arlindo Leal Boiça Júnior / Banca: Miguel Angelo Mutton / Resumo: Pratylenchus zeae, Meloidogyne javanica e M. incognita são nematoides-chave na cana-de-açúcar, no Brasil, mas P. brachyurus também é frequentemente encontrado. Três experimentos foram conduzidos para o estudo. No primeiro, comparou-se a agressividade de P. brachyurus e P. zeae a cultura. No segundo e no terceiro, buscaram-se alternativas de controle. O primeiro e o segundo experimentos foram em vasos de 100 L, a céu aberto e o terceiro em soqueira de quarto a quinto cortes. No primeiro foram inoculados 10, 100, 1.000, 10.000 e 100.000 espécimes/planta, isoladamente. No segundo foram testados Agrolmin® (ácidos húmicos e fúlvicos extraídos de turfa), Agrolmin + Fungos nematófagos (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofurano e Testemunha sem e com nematoides. No terceiro, testaram-se: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0,5 L.m linear-1)], FN (1 L.m linear-1), Formulação de FN (FFN) no Agrolmin Nitro (300 L.ha-1), FFN no Agrolmin Nitro (600 L.ha-1), Carbofurano (6 L.ha-1) e a Testemunha. Nos três experimentos foi avaliada a dinâmica da população das pragas e avaliações biométricas e quantitativas das plantas, ao final. Observou-se que a variedade CTC2 é suscetível à P. zeae e intolerante à P. brachyurus, que foi mais agressivo. Os FN incrementaram a produtividade, principalmente quando associados ao Agrolmin. O parasitismo de H. dihystera reduziu o de M. javanica, mas causou danos à cultura. A FFN no Agrolmin Nitro (300 L.ha-1) reduziu as populações de P. zeae e de M. javanica e elevou a produtividade em 14,6 Mg.ha-1, em relação a testemunha / Abstract: Pratylenchus zeae, Meloidogyne javanica and M. incognita are the key nematodes in sugar cane in Brazil, but P. brachyurus is also frequently found. Three experiments were conducted. In the first one, the aggressiveness of P. brachyurus and P. zeae to the crop was compared. In the second and third ones alternatives for the control were sought. The first and second experiments were carried out in 100 L pots, in open area and, the third experiment in ratoon of fourth to fifth cropping. In the first one levels of 10, 100, 1,000, 10,000 and 100,000 specimens/plant were inoculated, individually. In the second one it was tested Agrolmin ® (humic and fulvic acids extracted from peat), Agrolmin plus nematophagous fungi (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofuran and the Control with and without nematodes. In the third experiment were tested: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0.5 L.m linear -1)], FN (1 L.m linear-1) Formulation of FN (FFN) in Agrolmin Nitro (300 L.ha-1), FFN in Agrolmin Nitro (600 L.ha-1), Carbofuran (6 L.ha-1) and Control. In the three experiments it was analyzed the population dynamics of the nematodes as well biometric and quantitative assessments of the plants at the end. It was observed that the variety CTC2 is susceptible to P. zeae and intolerant to P. brachyurus which was more aggressive. The FN increased productivity, especially when associated with Agrolmin. The parasitism of H. dihystera reduced M. javanica population, but caused damage to the crop. The FFN in Agrolmin Nitro (300 L.ha-1) reduced populations of P. zeae and M. javanica and increased productivity by 14.6 Mg.ha-1, compared to control / Doutor

Au Canada, les pertes de rendement en agriculture attribuées aux nématodes sont généralement associées aux nématodes des lésions du genre Pratylenchus. En 2011, la découverte d’une nouvelle espèce exotique au Canada et qualifiée de rare dans le Nord-Est américain, soit Pratylenchus alleni Ferris, a soulevé de nouvelles inquiétudes. Afin de déterminer si cette espèce représente une menace pour les productions agricoles du Québec, mon projet de maîtrise visait à recueillir des informations sur sa virulence. Dans un premier temps, le spectre d’hôtes de P. alleni a été étudié et les résultats ont montré que ce nématode se développe très bien sur la pomme de terre, mais non sur la luzerne et le trèfle rouge. Ensuite, la reproduction de P. alleni dans un contexte de changements climatiques a été étudiée. L’augmentation prévue des températures et CO2 devrait favoriser le développement de P. alleni puisqu’il possède un meilleur taux de reproduction sur le soya lorsque soumis à un régime de températures de 17/28 ˚C et à une concentration en CO2 de 1200 ppm comparativement à 12/23 ˚C (400 ppm) et 15/26 ˚C (800 ppm). Dans cette même étude, une réduction de 19 à 58 % du poids sec racinaire des plants de soya inoculés avec P. alleni a été observée comparativement aux plants témoins. De plus, une méthode moléculaire de détection et de quantification simultanée de P. alleni et P. penetrans, l’espèce de Pratylenchus la plus répandu dans l’Est canadien, par qPCR a également été développée. Pour chacune des deux espèces, une sonde TaqMan associée avec le fluorophore CY5 pour P. alleni et FAM pour P. penetrans ciblant la région D2/D3 de la grande sous-unité ribosomale (28S) ont été développées et celles-ci se sont avérées spécifiques à chaque espèce. Ces résultats amènent de nouvelles connaissances sur ce ravageur et mettent en lumière sa pathogénicité. / In Canada, yield losses attributed to nematodes are generally associated with root-lesion nematodes from the genus Pratylenchus. In 2011, a new exotic species was detected in Canada and identified as Pratylenchus alleni Ferris. Pratylenchus alleni is rare in the Northeastern U.S. and its discovery has raised new concerns. To determine whether this species is a threat to agricultural production in Québec, my project aims to collect information about its pathogenicity. First, the host range of P. alleni was studied and the results showed that the nematode was developing well on potato, but poorly performed on alfalfa and red clover. The reproduction of P. alleni has also been studied in a context of climate change. The results showed that anticipated temperature and CO2 increases should favor P. alleni since it has a better reproduction rate on soybeans subjected to a night/day temperature regime of 17/28°C and a CO2 concentration of 1200 ppm compared to 12/23˚C (400 ppm) and 15/26°C (800 ppm) regimes. In the same study, a reduction of 19 to 58 % of roots dry weight of soybeans inoculated with P. alleni was observed compared to control plants. A simultaneous molecular detection and quantification method by qPCR of P. alleni and P. penetrans, the most widespread Pratylenchus species in Eastern Canada, was also developed. For each species, a TaqMan probe associated with the CY5 fluorophore for P. alleni and FAM for P. penetrans targeting the D2/D3 expansion segments of the large ribosomal subunit (28S) were developed and proved to be specific to each species. These results bring new insights into this new pest and highlight its pathogenicity.