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Alberto Bressan - One of the best experts on this subject based on the ideXlab platform.
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Characterization and evolution of two bacteriome-inhabiting symbionts in cixiid planthoppers (Hemiptera: Fulgoromorpha: Pentastirini)
Environmental Microbiology, 2009Co-Authors: Alberto Bressan, Joel Demian Arneodo Larochette, Mauro Simonato, William Haines, Elisabeth Boudon-padieuAbstract:Like other plant sap-sucking insects, planthoppers within the family Cixiidae (Insecta: Hemiptera: Fulgoromorpha) host a diversified microbiota. We report the identification and first molecular characterization of symbiotic bacteria in cixiid planthoppers (tribe: Pentastirini). Using universal eubacterial primers we first screened the eubacterial 16S rRNA sequences in Pentastiridius Leporinus (Linnaeus) with PCR amplification, cloning, and restriction fragment analysis. We identified three main 16S rRNA sequences that corresponded to a Wolbachia bacterium, a plant pathogenic bacterium, and a novel gammaproteobacterial symbiont. A fourth bacterial species affiliated with ‘Candidatus Sulcia muelleri’ was detected in PCR assays using primers specific for the Bacteroidetes. Within females of two selected cixiid planthoppers, P. Leporinus and Oliarus filicicola, fluorescence In situ hybridization analysis and transmission electron microscopy observations showed that ‘Ca. Sulcia muelleri’ and the novel gammaproteobacterial symbiont were housed in separate bacteriomes. Phylogenetic analysis revealed that both of these symbionts occurred in at least four insect genera within the tribe Pentastirini. ‘Candidatus Purcelliella pentastirinorum’ was proposed as the novel gammaproteobacterial symbiont.
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Insect Vectors (Hemiptera: Cixiidae) and Pathogens Associated with the Disease Syndrome “Basses Richesses” of Sugar Beet in France
Plant Disease, 2008Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Denis Clair, Elisabeth Boudon-padieuAbstract:The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius Leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. Leporinus was considered to be the economic vector of SBR disease. C. wagneri, the primary vector of ‘Candidatus Phlomobacter fragariae’ to strawberry in western France, also was found to be infected by the SBR bacterium and to transmit the pathogen to sugar beet. Neither C. wagneri nor P. Leporinus were infected by stolbur phytoplasma. Populations of H. obsoletus living on bindweed (Convolvulus arvensis) and nettle (Urtica dioica) collected near sugar beet fields did not carry the SBR bacterium, but were highly infected with two restriction fragment length polymorphism-differentiable stolbur phytoplasma isolates. In transmission assays, only the bindweed phytoplasma isolate was transmissible to and pathogenic on sugar beet. When compared with controls, the bindweed stolbur phytoplasma and SBR bacterium similarly reduced the biomass of sugar beet plants, but the phytoplasma caused greater reductions in taproot biomass and sugar content than the SBR bacterium.
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insect vectors hemiptera cixiidae and pathogens associated with the disease syndrome basses richesses of sugar beet in france
Plant Disease, 2008Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Denis Clair, E BoudonpadieuAbstract:ABSTRACT The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius Leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. Leporinus was considered to be the economic vector of SBR disease. C. wagneri, the primary vector of ‘Candidatus Phlomobacter fragariae’ to strawberry in western France, also was found to be infected by the SBR bacterium and to transmit the pathogen to sugar beet. Neither C. wagneri nor P. Leporinus were infected by stolbur phytoplasma. Populations of H. obsoletus living on bindweed (Convolvulus arvensis) and nettle (Ur...
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The syndrome "basses richesses" of sugar beet in France is associated with different pathogen types and insect vectors
Bulletin of Insectology, 2007Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Elisabeth BoudonAbstract:The syndrome “basses richesses” (SBR) of sugar beet in France is associated with two phloem-restricted uncultivable bacteria: a stolbur phytoplasma and a y-3 proteobacteria. The known vector of proteobacteria is a cixiid planthopper, Pentastiridius Leporinus (Hemiptera Cixiidae), formerly shown to transmit both the prokaryotes. The role of P. Leporinus and of two other planthopper species, Cixius wagneri and Hyalesthes obsoletus, in spreading the two pathogens to sugar beet were compared and quantified. Because of its abundance and high infection rates with proteobacterium, P. Leporinus was confirmed to be the economic vector of SBR disease. P. Leporinus and C. wagneri were infected by and transmitted proteobacterium, neither was infected by the phytoplasma. Neither of two populations of H. obsoletus living near sugar beet fields on bindweed and nettle respectively, carried proteobacterium but they were highly infected with two RFLP-differentiable stolbur types. Only the bindweed stolbur type was transmitted and pathogenic to sugar beets. Symptoms associated with the two prokaryotes were similar, but stolbur caused a stronger reduction on taproot biomass and sugar content than proteobacteria. This work underlines possible confusion in aetiology of diseases associated with phytoplasmas or phloem-restricted proteobacteria and the increasing importance of the latter plant pathogens.
Elisabeth Boudon-padieu - One of the best experts on this subject based on the ideXlab platform.
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Characterization and evolution of two bacteriome-inhabiting symbionts in cixiid planthoppers (Hemiptera: Fulgoromorpha: Pentastirini)
Environmental Microbiology, 2009Co-Authors: Alberto Bressan, Joel Demian Arneodo Larochette, Mauro Simonato, William Haines, Elisabeth Boudon-padieuAbstract:Like other plant sap-sucking insects, planthoppers within the family Cixiidae (Insecta: Hemiptera: Fulgoromorpha) host a diversified microbiota. We report the identification and first molecular characterization of symbiotic bacteria in cixiid planthoppers (tribe: Pentastirini). Using universal eubacterial primers we first screened the eubacterial 16S rRNA sequences in Pentastiridius Leporinus (Linnaeus) with PCR amplification, cloning, and restriction fragment analysis. We identified three main 16S rRNA sequences that corresponded to a Wolbachia bacterium, a plant pathogenic bacterium, and a novel gammaproteobacterial symbiont. A fourth bacterial species affiliated with ‘Candidatus Sulcia muelleri’ was detected in PCR assays using primers specific for the Bacteroidetes. Within females of two selected cixiid planthoppers, P. Leporinus and Oliarus filicicola, fluorescence In situ hybridization analysis and transmission electron microscopy observations showed that ‘Ca. Sulcia muelleri’ and the novel gammaproteobacterial symbiont were housed in separate bacteriomes. Phylogenetic analysis revealed that both of these symbionts occurred in at least four insect genera within the tribe Pentastirini. ‘Candidatus Purcelliella pentastirinorum’ was proposed as the novel gammaproteobacterial symbiont.
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Insect Vectors (Hemiptera: Cixiidae) and Pathogens Associated with the Disease Syndrome “Basses Richesses” of Sugar Beet in France
Plant Disease, 2008Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Denis Clair, Elisabeth Boudon-padieuAbstract:The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius Leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. Leporinus was considered to be the economic vector of SBR disease. C. wagneri, the primary vector of ‘Candidatus Phlomobacter fragariae’ to strawberry in western France, also was found to be infected by the SBR bacterium and to transmit the pathogen to sugar beet. Neither C. wagneri nor P. Leporinus were infected by stolbur phytoplasma. Populations of H. obsoletus living on bindweed (Convolvulus arvensis) and nettle (Urtica dioica) collected near sugar beet fields did not carry the SBR bacterium, but were highly infected with two restriction fragment length polymorphism-differentiable stolbur phytoplasma isolates. In transmission assays, only the bindweed phytoplasma isolate was transmissible to and pathogenic on sugar beet. When compared with controls, the bindweed stolbur phytoplasma and SBR bacterium similarly reduced the biomass of sugar beet plants, but the phytoplasma caused greater reductions in taproot biomass and sugar content than the SBR bacterium.
José L. O. Birindelli - One of the best experts on this subject based on the ideXlab platform.
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New species of Leporinus (Characiformes: Anostomidae) from the highlands of the Guiana Shield in Venezuela
Neotropical Ichthyology, 2019Co-Authors: José L. O. Birindelli, Heraldo A. Britski, Francisco ProvenzanoAbstract:ABSTRACT A new species of Leporinus is described using morphological data and compared to all other species of the family. Specimens were illustrated using digital photograph, measured using digital calipers, and had teeth, scales, and fin rays counted under a stereomicroscope. The new species is distinguished from all other Anostomidae, except Anostomus anostomus, A. brevior, A. ternetzi, Hypomasticus despaxi, Leporinus arcus, and L. striatus, by having four dark longitudinal stripes on body. The new species is distinguished from aforementioned species by having terminal mouth with four teeth on the premaxilla, 12 series of scales around caudal peduncle, and 34 to 36 scales in the lateral line. The new species is remarkably similar to Leporinus arcus, which occurs on the opposite side of Guyana Shield highlands. The new species and L. arcus are possibly closely related to Leporinus gomesi, L. granti, L. lebaili, L. melanostictus, L. nijsseni, and L. santosi.
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Systematic assessment of the Leporinus desmotes species complex, with a description of two new species
Neotropical Ichthyology, 2017Co-Authors: Michael D. Burns, José L. O. Birindelli, Marcus Chatfield, Brian L. SidlauskasAbstract:ABSTRACT Members of the Leporinus desmotes species complex can be distinguished from other barred or banded congeners by the combination of nine distinct black bars across the head and trunk and long, pointed, laterally compressed and upward curving symphyseal dentary teeth. A taxonomic reassessment of this complex revealed two new species, one from the Orinoco and Negro rivers of Venezuela and Brazil, and the other from the Xingu and Tapajós rivers of Brazil. Both species are similar to L. desmotes and L. jatuncochi, but differ significantly in body shape morphology, coloration, and/or circumpeduncular scale counts. Genetic evidence also contributes to the recognition of both new species. This contribution also maps the geographic distribution of the four known species, and highlights the presence of an unusual meristic polymorphism within Leporinus desmotes sensu stricto that may suggest the presence of even more unrecognized diversity.
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Two new species of Leporinus Agassiz, 1929 (Characiformes: Anostomidae) from tributaries of the lower Amazon basin in Brazil
Zootaxa, 2016Co-Authors: José L. O. Birindelli, Tulio F. TeixeiraAbstract:Two new species of Leporinus (Characiformes, Anostomidae) are described. Both new species are diagnosed by having one dark blotch on midline of anterior portion of the flank (between opercle and pelvic-fin origin) surrounded by five to seven dark blotches; and a subinferior mouth with three premaxillary teeth. Leporinus multimaculatus , new species, is distributed in small and medium-sized tributaries of the rio Tocantins and rio Xingu basins, and also in the rio Jari and coastal drainages of Amapa state, whereas L. torrenticola , new species, is endemic to the rapids of the rio Xingu and its main tributaries. The number of scale rows around the caudal peduncle is the main feature distinguishing L. multimaculatus from L. torrenticola . Comments on the diagnostic features of the newly described species are provided. In addition, the phylogenetic position and generic assignment of the new species are discussed based on available information from recent morphological and molecular analyses.
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Redescription of Leporinus jamesi (Characiformes: Anostomidae), a poorly known species of Leporinus from the lowlands of the central Amazon, Brazil
Neotropical Ichthyology, 2014Co-Authors: Julio Cesar Garavello, Heraldo A. Britski, José L. O. BirindelliAbstract:The poorly known Leporinus jamesiis redescribed. The species was originally described based on a single specimen collected in the rio Solimoes at Manacapuru, in the central Amazon, Brazil. The holotype went missing before the species description was finished and published, and remained lost for more than a hundred years. Leporinus jamesi is distinguished from its congeners by having pectoral and pelvic fins dark, 42 to 45 scales on the lateral line, 16 scale series around the caudal peduncle, a body with two conspicuous dark midlateral blotches (the blotch on the caudal peduncle absent or inconspicuous), and four teeth on the premaxilla and dentary, including a bicuspid symphyseal tooth on the premaxilla. A principal component analysis on morphometric traits between combined samples of L. jamesi and L. amazonicus was performed showing significant morphometric differences between these species. In addition, inaccuracies in Borodin's descriptions of various species of the genus Leporinus are discussed.
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Two new species of Leporinus (Characiformes: Anostomidae) from the Brazilian Amazon, and redescription of Leporinus striatus Kner 1858
Journal of fish biology, 2013Co-Authors: José L. O. Birindelli, Heraldo A. BritskiAbstract:Two new species of Leporinus are described from tributaries of the Rio Amazonas in Brazil. One species is known from the Jari and Tapajos River basins, and is identified on the basis of a gas bladder reduced in size, a dark midlateral stripe on the body, dark transverse bars on the dorsum, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle. The second new species is known from the Tocantins, Xingu and Tapajos River basins, and is identified on the basis of three dark longitudinal stripes on the body, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 12 scale rows around the caudal peduncle. In addition, Leporinus striatus is redescribed based on type and additional specimens from the Rio de La Plata, Amazonas, Orinoco, Atrato, Magdalena and Sinu River basins. Leporinus striatus is identified on the basis of four dark longitudinal stripes on the body, a subterminal mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle.
Heraldo A. Britski - One of the best experts on this subject based on the ideXlab platform.
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New species of Leporinus (Characiformes: Anostomidae) from the highlands of the Guiana Shield in Venezuela
Neotropical Ichthyology, 2019Co-Authors: José L. O. Birindelli, Heraldo A. Britski, Francisco ProvenzanoAbstract:ABSTRACT A new species of Leporinus is described using morphological data and compared to all other species of the family. Specimens were illustrated using digital photograph, measured using digital calipers, and had teeth, scales, and fin rays counted under a stereomicroscope. The new species is distinguished from all other Anostomidae, except Anostomus anostomus, A. brevior, A. ternetzi, Hypomasticus despaxi, Leporinus arcus, and L. striatus, by having four dark longitudinal stripes on body. The new species is distinguished from aforementioned species by having terminal mouth with four teeth on the premaxilla, 12 series of scales around caudal peduncle, and 34 to 36 scales in the lateral line. The new species is remarkably similar to Leporinus arcus, which occurs on the opposite side of Guyana Shield highlands. The new species and L. arcus are possibly closely related to Leporinus gomesi, L. granti, L. lebaili, L. melanostictus, L. nijsseni, and L. santosi.
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Molecular identification of Leporinus from the south portion of South America
DNA Barcodes, 2015Co-Authors: Gleisy S. Avelino, Heraldo A. Britski, Fausto Foresti, Claudio OliveiraAbstract:AbstractAnostomidae is a widely distributed group that includes the species rich Leporinus. This genus is widespread in South America, including its south portion where they are mainly distributed in the São Francisco and La Plata basins. Here we obtained sequences of mitochondrial and nuclear genes of 19 species of Leporinus with the objective of testing our methods of molecular species identification and to test the similarities between species of Leporinus of the São Francisco and La Plata basins. Results show that two species pair have a genetic distance below 2% (L. paranensis x L. obtusidens and L. paranensis x L. aff. paranensis). Our results also show that a high genetic distance occurs in L. obtusidens and L. striatus suggesting a possible local differentiation of these species. An interesting finding of our study is that the genetic similarities observed among species does not corroborate the division of species of Leporinus in groups according to color patterns. Additionally, our results show that the species of Leporinus from the La Plata and São Francisco are not more similar among themselves than to species of other drainages which could be explained by the occurrence of recent fauna exchanges between these two basins and adjacent basins.
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Redescription of Leporinus jamesi (Characiformes: Anostomidae), a poorly known species of Leporinus from the lowlands of the central Amazon, Brazil
Neotropical Ichthyology, 2014Co-Authors: Julio Cesar Garavello, Heraldo A. Britski, José L. O. BirindelliAbstract:The poorly known Leporinus jamesiis redescribed. The species was originally described based on a single specimen collected in the rio Solimoes at Manacapuru, in the central Amazon, Brazil. The holotype went missing before the species description was finished and published, and remained lost for more than a hundred years. Leporinus jamesi is distinguished from its congeners by having pectoral and pelvic fins dark, 42 to 45 scales on the lateral line, 16 scale series around the caudal peduncle, a body with two conspicuous dark midlateral blotches (the blotch on the caudal peduncle absent or inconspicuous), and four teeth on the premaxilla and dentary, including a bicuspid symphyseal tooth on the premaxilla. A principal component analysis on morphometric traits between combined samples of L. jamesi and L. amazonicus was performed showing significant morphometric differences between these species. In addition, inaccuracies in Borodin's descriptions of various species of the genus Leporinus are discussed.
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Two new species of Leporinus (Characiformes: Anostomidae) from the Brazilian Amazon, and redescription of Leporinus striatus Kner 1858
Journal of fish biology, 2013Co-Authors: José L. O. Birindelli, Heraldo A. BritskiAbstract:Two new species of Leporinus are described from tributaries of the Rio Amazonas in Brazil. One species is known from the Jari and Tapajos River basins, and is identified on the basis of a gas bladder reduced in size, a dark midlateral stripe on the body, dark transverse bars on the dorsum, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle. The second new species is known from the Tocantins, Xingu and Tapajos River basins, and is identified on the basis of three dark longitudinal stripes on the body, a subinferior mouth, three teeth on the premaxilla, four teeth on the dentary and 12 scale rows around the caudal peduncle. In addition, Leporinus striatus is redescribed based on type and additional specimens from the Rio de La Plata, Amazonas, Orinoco, Atrato, Magdalena and Sinu River basins. Leporinus striatus is identified on the basis of four dark longitudinal stripes on the body, a subterminal mouth, three teeth on the premaxilla, four teeth on the dentary and 16 scale rows around the caudal peduncle.
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New Species of Leporinus from the Rio Tapajós Basin, Brazil, and Redescription of L. moralesi (Characiformes: Anostomidae)
Copeia, 2013Co-Authors: José L. O. Birindelli, Heraldo A. Britski, Flávio C. T. LimaAbstract:Leporinus moralesi is a poorly known species from central Amazon basin, Brazil, which is redescribed based on examination of type specimens and additional material. The species is diagnosed by having a dark midlateral stripe running from the vertical through the dorsal fin to the end of the middle caudal-fin rays, 35 to 38 lateral-line scales, five scale rows between the dorsal fin and the lateral line, four or five scale rows between the lateral line and the pelvic fin, 16 scale rows around the caudal peduncle, three teeth on the premaxilla and four on the dentary. Leporinus uatumaensis, described from the Rio Uatuma, a tributary of the Rio Amazonas immediately downstream from Manaus, is a junior synonym of L. moralesi. A lectotype is designated herein for Leporinus muelleri ( = L. moralesi). In addition, a new species of Leporinus from the Rio Tapajos, Para, Brazil, is described. The new species shares with Leporinus moralesi the presence of symphyseal tooth of the premaxilla with two cusps of similar s...
Olivier Sémétey - One of the best experts on this subject based on the ideXlab platform.
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Insect Vectors (Hemiptera: Cixiidae) and Pathogens Associated with the Disease Syndrome “Basses Richesses” of Sugar Beet in France
Plant Disease, 2008Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Denis Clair, Elisabeth Boudon-padieuAbstract:The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius Leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. Leporinus was considered to be the economic vector of SBR disease. C. wagneri, the primary vector of ‘Candidatus Phlomobacter fragariae’ to strawberry in western France, also was found to be infected by the SBR bacterium and to transmit the pathogen to sugar beet. Neither C. wagneri nor P. Leporinus were infected by stolbur phytoplasma. Populations of H. obsoletus living on bindweed (Convolvulus arvensis) and nettle (Urtica dioica) collected near sugar beet fields did not carry the SBR bacterium, but were highly infected with two restriction fragment length polymorphism-differentiable stolbur phytoplasma isolates. In transmission assays, only the bindweed phytoplasma isolate was transmissible to and pathogenic on sugar beet. When compared with controls, the bindweed stolbur phytoplasma and SBR bacterium similarly reduced the biomass of sugar beet plants, but the phytoplasma caused greater reductions in taproot biomass and sugar content than the SBR bacterium.
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insect vectors hemiptera cixiidae and pathogens associated with the disease syndrome basses richesses of sugar beet in france
Plant Disease, 2008Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Denis Clair, E BoudonpadieuAbstract:ABSTRACT The syndrome “basses richesses” (SBR) is a disease of sugar beet in eastern France associated with two phloem-restricted, nonculturable plant pathogens: a stolbur phytoplasma and a γ-3 proteobacterium, here called SBR bacterium. Three planthopper (Hemiptera: Cixiidae) species were found to live near and within sugar beet fields in eastern France: Cixius wagneri, Hyalesthes obsoletus, and Pentastiridius Leporinus. The role of these planthoppers in spreading the two pathogens to sugar beet was studied. Based on its abundance and high frequency of infection with the SBR bacterium, P. Leporinus was considered to be the economic vector of SBR disease. C. wagneri, the primary vector of ‘Candidatus Phlomobacter fragariae’ to strawberry in western France, also was found to be infected by the SBR bacterium and to transmit the pathogen to sugar beet. Neither C. wagneri nor P. Leporinus were infected by stolbur phytoplasma. Populations of H. obsoletus living on bindweed (Convolvulus arvensis) and nettle (Ur...
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The syndrome "basses richesses" of sugar beet in France is associated with different pathogen types and insect vectors
Bulletin of Insectology, 2007Co-Authors: Alberto Bressan, Benoit Nusillard, Olivier Sémétey, Elisabeth BoudonAbstract:The syndrome “basses richesses” (SBR) of sugar beet in France is associated with two phloem-restricted uncultivable bacteria: a stolbur phytoplasma and a y-3 proteobacteria. The known vector of proteobacteria is a cixiid planthopper, Pentastiridius Leporinus (Hemiptera Cixiidae), formerly shown to transmit both the prokaryotes. The role of P. Leporinus and of two other planthopper species, Cixius wagneri and Hyalesthes obsoletus, in spreading the two pathogens to sugar beet were compared and quantified. Because of its abundance and high infection rates with proteobacterium, P. Leporinus was confirmed to be the economic vector of SBR disease. P. Leporinus and C. wagneri were infected by and transmitted proteobacterium, neither was infected by the phytoplasma. Neither of two populations of H. obsoletus living near sugar beet fields on bindweed and nettle respectively, carried proteobacterium but they were highly infected with two RFLP-differentiable stolbur types. Only the bindweed stolbur type was transmitted and pathogenic to sugar beets. Symptoms associated with the two prokaryotes were similar, but stolbur caused a stronger reduction on taproot biomass and sugar content than proteobacteria. This work underlines possible confusion in aetiology of diseases associated with phytoplasmas or phloem-restricted proteobacteria and the increasing importance of the latter plant pathogens.