Different Regions Of Bulgaria Research Articles

Mycobacterium tuberculosis Latin–American–Mediterranean family in Bulgaria

IntroductionTuberculosis (TB) remains an important public health issue for Bulgaria. Although a number of new cases are showing a steady decline (44/100,000 in 2000, 40/100,000 in 2005), the TB incidence rate in Bulgaria is still sufficiently high (26.7/100,000 in 2013). The current population structure of Mycobacterium tuberculosis is clonal. Certain genetic families of this species have justly attracted more attention due to their global dissemination and/or remarkable pathogenic properties. Beijing, Haarlem, and LAM are the most known examples. The latter family LAM (Latin–American–Mediterranean) was shown in an increasing number of studies to possess increased transmissibility, hence the importance of its rapid detection and correct estimation of its prevalence in a population. Spoligotyping signature of LAM is absence of signals 21–24 and 33–36, although abridged spoligo-profiles with long blocks of deleted spacers result in an uncertain definition of such strains. The use of other molecular markers may be helpful. This study aimed to evaluate the prevalence of LAM strains among M. tuberculosis strains in Bulgaria based on the use of different molecular markers. Materials and methodsM. tuberculosis isolates were randomly selected among M. tuberculosis strains isolated from newly diagnosed, adult, pulmonary TB patients in different regions of Bulgaria from December 2004 to March 2006. Spoligotyping was used to analyze a variation in the DR locus. The spoligotyping patterns were compared with the international database SITVIT_WEB (Institut Pasteur de Guadeloupe). Analysis of the IS6110 element specific for the LAM genetic family was performed as described previously (Marais et al., 2006). ResultsA study sample included 133 strains from different regions of the country and characterized in previous publications (Valcheva et al., 2008, 2010). Application of the published rules for the definition of the major spoligotype clades and comparison with SITVIT_WEB global database permitted this study to assign most of the 133 strains to the known spoligotype families. All available strains (n=101) were tested for LAM-specific IS6110 insertion. Comparison of results by different methods identified 3 groups of strains. The first group included 11 strains with 2 amplified bands which present an apparent discrepancy; further study is warranted. The second group included 86 strains with a single amplified band, specific for the absence of the IS6110 insertion in the target locus, hence indicative of the other than LAM family. The third group included 4 strains with a LAM-specific band only. ConclusionsApplication of the LAM-specific PCR revealed double-sided discrepancies when the obtained results were compared with those obtained by spoligotyping. As a whole, a phylogenetic family of 38 strains was revised or questioned: 27 strains were shown not to belong to LAM, while 11 more strains showed apparently discrepant results that question the global utility of such PCR or at least highlight an importance of using multiple markers for molecular detection of the LAM family of M. tuberculosis. AcknowledgementsDr. Nadya Markova, Prof. Olga Narvskaya, and Prof. Nalin Rastogi are gratefully acknowledged for kind support and guidance.

Technogenic radionuclides in undisturbed Bulgarian soils

This work presents data for the activity concentration of artificial radionuclides in soils from different regions in Bulgaria for the period 1985–2011. The subjects of the study were undisturbed soils from mountainous, hilly, and plain areas. Special attention has been paid to the contamination with the long-lived technogenic radionuclides cesium-137, strontium-90, plutonium-238, and plutonium-239+240. 137Cs was measured by low level gamma spectrometry and 90Sr by radiochemical separation and low level beta counting. The isotopes of plutonium were measured by alpha-spectrometry after a radiochemical procedure of purification and concentration.Cesium-137 and strontium-90 were the main technogenic radionuclides detected in the examined Bulgarian soils few years after the Chernobyl NPP accident. Their content in the soils from high mountain areas is several times higher than that in the soils from the plane areas in the northern part of the country. High heterogeneity in the pollution has been observed. Mean soil activity concentration levels of up to 250Bqkg−1 for 137Cs and 14Bqkg−1 for 90Sr were found in different years. The maximal values registered in separate soil samples were about 1300Bqkg−1 (137Cs) and 24Bqkg−1 (90Sr). The activity concentration levels for 239+240Pu varied between 0.1 and 3.7Bqkg−1. The results indicate that the radioactive pollution of the Bulgarian soils with artificial radionuclides is a result of global fallout and Chernobyl nuclear power plant accident.

Rodents as reservoirs of human pathogens in Bulgaria

Small mammals are reservoirs of various human pathogens. The aim of this work was to investigate infections with human pathogens in rodents trapped in different regions of Bulgaria. A total of 284 rodents were investigated by PCR for detection of the flagellin gene of borreliae within Borrelia burgdorferi sensu lato complex, ankA gene of Anaplasma phagocytophilum and nucleoprotein gene of hantavirus Dobrava - conventional nested RT-PCR and Real Time PCR with TaqMan probe. B. burgdorferi was detected in 64/284 (22.5%) of the investigated rodents by PCR. Of them, 41 samples originated from Apodemus flavicollis, 20 from A. agrarius, and 3 from A. sylvaticus. Overall, 33 of the investigated 284 rodents were infected with Anaplasma phagocytophilum (11.6%) - 11 Apodemus flavicollis (infectivity rate 8.6% of the 128 investigated), 13 Apodemus agrarius (infectivity rate 13.5% of the 96 tested), and 1 Apodemus sylvaticus (infectivity rate 9% of the 11 tested). Hantavirus RNA was detected in 9 of the rodents. Only Dobrava-Belgrade virus but not Puumala or Saaremaa virus was detected. Almost all infected rodents were A. flavicollis (8/9 PCR-positive rodents). Rodents are important reservoirs of human pathogens. In this study, active infection in rodents was confirmed by detection of microorganism's genome. Remarkably, a high number of rodents from genus Apodemus were infected with borreliae. The high rate of detection of A. phagocytophilum in rodents from A. agrarius species suggested that this species might serve as major reservoir of human anaplasmosis in Bulgaria. Mainly infected with hantaviruses were A. flavicollis mice, known as reservoir of Dobrava hantavirus but hantavirus infections were detected also in A. agrarius mice. Medical authorities should be aware of the risk for humans.

Catches of target and non-target scarab pests in floral-chemical baited color traps in Bulgaria

Field investigations with CSALOMON® floral-chemical baited color traps for scarab beetles (Coleoptera: Scarabaeidoidaea) were organized in eight sites in different regions in Bulgaria during 2009–2010. As a result data about distribution and seasonal flight were obtained for the target species Cetonia aurata L. and Protaetia cuprea (Fabricius) and two other non-target species, Valgus hemipterus L. and Blitopertha lineolata (Fischer von Waldheim). Catches of C. aurata were recorded in all of the sites where observations were organized but the number of the beetles caught was relatively low. The earliest catches of this pest were registered in the middle-end of April and the latest ones in early August. Single catches of P. cuprea, not allowing doing conclusions about seasonal flight for this species, were recorded only in Dryanovo, Knezha, Plovdiv and Troyan. Catches of V. hemipterus, were registered in all of the sites with the exception of Petrich. The flight period of this species, as established by catches in the traps, was middle-end of April — early June. Significant number of B. lineolata was caught in Dryanovo in 2009 and single catches in Plovdiv in 2009 and Kyustendil in 2009 and 2010. The earliest catches for the two years in Dryanovo were registered in the middle-end of May and the latest ones in the middle of June. This is the first report about floral-chemical attractant for this species. For all four species the relative catches in traps for C. aurata/P. cuprea, Tropinota (Epicometis) hirta (Poda) and Oxythyrea funesta (Poda), operating simultaneously in the investigated sites, were presented and analyzed.

Biologically Active Compounds with Antitumor Activity in Propolis Extracts from Different Geographic Regions

ABSTRACTSeven propolis samples (S1—S7) from different regions of Bulgaria and eight commercial products of propolis extracts (C8—C15) from various European countries were studied. Concentrations of five antitumor compounds: CAPE, quercetin, rutin, p-coumaric acid, and ferulic acid, were determined and a comparison between the propolis extracts from different regions was made. The results showed that among samples S1—S7, two were distinctive with their high concentrations of CAPE and quercetin: S1 (Asenovgrad region)—9843.6 μg/mL and 2575.6 μg/mL, respectively, and S7 (Smolyan region)—10270.2 μg/mL and 2575.6 μg/mL, respectively. Sample S4 (Plovdiv region) showed significant amounts of p-coumaric acid (1638.2 μg/mL) and ferulic acid (1186.5 μg/mL). Sample C11 from the commercial propolis extract products (Bulgaria) was distinctive with its high concentrations of CAPE (5802.3 μg/mL), p-coumaric acid (2955.2 μg/mL) and ferulic acid (1081.2 μg/mL). Samples C15 (Italy) and C8 (Austria) also contained significant amounts of CAPE, quercetin, p-coumaric acid, and ferulic acid. The overall results showed high content variability of the five biologically active substances analyzed. Nevertheless, each sample contained significant amounts of at least four of the biologically active compounds tested, which confirms that propolis remains a valuable source of antitumor compounds.

Nosocomial transmission of measles among healthcare workers, Bulgaria, 2010

This report describes 326 cases of nosocomial transmission of measles with 286 cases among non-healthcare workers who acquired the disease in a hospital setting. Between October 2009 and April 2010, 40 healthcare workers from seven different regions in Bulgaria have contracted the disease.

Species composition and morphology of protostrongylids (Nematoda: Protostrongylidae) in ruminants from Bulgaria

Lungs of 52 ruminants from different regions of Bulgaria, 16 from goats (Capra aegagrus f. domestica L.), 15 from sheep (Ovis ammon f. domestica L.), 11 from mouflons (Ovis musimon L.), and 10 from chamois (Rupicapra rupicapra L.), were investigated. The aim of the study was to determine the species composition of small lungworms in these hosts. The obtained results are summarized with those of previous studies, and a picture of the present status of the species composition of protostrongylids in ruminants from Bulgaria is forwarded. Morphometric data about the species Muellerius capillaris, Cystocaulus ocreatus, Neostrongylus linearis, Protostrongylus brevispiculum, and Protostrongylus rufescens are presented. The data on the morphology of these five species are supplied for the first time both for Bulgaria and the south-east part of the European continent.

Utilization of Carbohydrates by Beauveria Bassiana Isolates Obtained from Forest Pests

Carbohydrate utilization profiles of ten isolates of the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuillemin were studied and compared to assist in determining their phenotypic characterization. Isolates were obtained in pure cultures from dead individuals of several forest pests collected from different regions in Bulgaria. Studies on utilization profiles were based on the acidification of twenty carbohydrates. The results indicate that sucrose, maltose and trehalose were assimilated at a high degree compared to esculin, arabinose and dul- citol. According to the results of a cluster analysis of the carbohydrate utilization profiles, the B. bassiana isolates were divided into two larger groupings. All isolates in the first larger cluster were obtained from the coleopteran insects - Stenomax aeneus, Ips typographus, I. sexdentatus and Dryocoetes autographus. Isolates from the other cluster were obtained from the lepidopteran larvae of Thaumetopoea pityocampa and Lymantria dispar, and from an adult of the coleopteran species Hylurgops palliatus. We determined that each B. bassiana isolate exhibited a different and specific carbohydrate utilization profile but differences at the p-level < 0.05 were significant among some of them. The most distinguishable was the isolate 560Bb obtained from T. pityocampa. Differences between the isolate 560Bb and the other nine B. bassiana isolates were highly significant at the p-level < 0.005. Isolate 433Bb obtained from a dead adult of I. typogra- phus was significantly different from five of the studied isolates at the p-level < 0.05.

Molecular snapshot of drug-resistant and drug-susceptible Mycobacterium tuberculosis strains circulating in Bulgaria

We report results of the first study on the molecular basis of drug resistance in Mycobacterium tuberculosis strains currently circulating in Bulgaria. The study panel consisted of 133 (including 37 drug-resistant) isolates recovered from newly diagnosed, adult pulmonary TB patients from different regions of Bulgaria in 2005–2006. Three types of the rpoB mutations were found in 20 of 27 RIF-resistant isolates; rpoB S531L was the most frequent. Eleven (48%) of 23 INH-resistant isolates had katG S315T mutation. inhA −15C > T mutation was detected in one INH-resistant isolate (that also had katG315 mutation) and three INH-susceptible isolates. A mutation in embB306 was found in 7 of 11 EMB-resistant isolates. Comparison with spoligotyping and 24-VNTR locus typing data suggested that emergence and spread of drug-resistant and MDR-TB in Bulgaria are not associated with any specific spoligotype or MIRU-VNTR genotype.

Molecular Characterization ofMycobacterium tuberculosisIsolates from Different Regions of Bulgaria

Mycobacterium tuberculosis isolates from different regions of Bulgaria were studied by a variety of molecular typing tools. Based on spacer oligonucleotide typing (spoligotyping), the 113 strains were subdivided into 35 spoligotypes: 5 unique profiles and 15 profiles shared by two to 29 strains; the Hunter-Gaston diversity index (HGI) was 0.9. Comparison with the international database SITVIT2 at the Institut Pasteur de Guadeloupe showed the presence of two globally distributed shared types, ST53 (25.7%) and ST47 (6.2%). Nineteen (16.8%) and six (5.3%) strains belonged to the ST125 (LAM/S subfamily) and ST41 (LAM7_TUR subfamily) types described in SITVIT2 as ubiquitous/rare and ubiquitous/common types, respectively. Seven spoligoprofiles (12 strains) were not found in the database; two of them constituted new shared types. The Beijing genotype strains were not found in the studied collection in spite of close contacts with Russia in the recent and historical past. Additional subtyping by IS6110-restriction fragment length polymorphism (RFLP) and 12-locus mycobacterial interspersed repetitive unit (MIRU)-variable number of tandem repeat analyses were performed within selected spoligotypes. In particular, MIRU typing showed better discrimination within ST125 than IS6110-RFLP typing (HGI = 0.83 versus 0.39). A high gradient for ST125 in Bulgaria compared to its negligible presence in the global database and neighboring countries leads us to suggest a Bulgarian phylogeographic specificity of this spoligotype. To conclude, this first study of the Bulgarian M. tuberculosis population demonstrated its heterogeneity and predominance of several worldwide-distributed and Balkan-specific spoligotypes.

Multiple differentiation centres of a non‐Mediterranean butterfly species in south‐eastern Europe

AbstractAim The analysis of the phylogeographical structures of many European species reveals the importance of Mediterranean glacial refugia for many thermophilic species, but also underlines the relevance of extra‐Mediterranean glacial differentiation centres for a number of temperate species. In this context, phylogeographical analyses of species from south‐eastern Europe are highly important for a comprehensive understanding of Europe as a whole.Location Romania and Bulgaria.Methods We analysed 19 allozyme loci for 615 individuals of the temperate butterfly species Erebia medusa from 28 populations.Results These populations had an intermediate genetic diversity, but the Bulgarian populations were significantly more diverse than the ones north of the Danube in Romania. The differentiation among populations was strong, and 52.1% of the genetic variance among populations was distributed between these two countries. The genetic differentiation was considerably stronger in Romania than in Bulgaria, but several sublineages were distinguished within each of these countries.Main conclusions The observed genetic structure is so strong that it is most probably the result of glacial differentiation processes in south‐eastern Europe and not a post‐glacial structure. The strong differentiation into the two groups north and south of the Danube suggests a separating effect by this river valley. The strong differentiation accompanied with genetic impoverishment in Romania suggests the existence of several differentiation centres: at least two small ones on the southern slopes of the southern Carpathians and one in the eastern Carpathian Basin. The considerably weaker differentiation among the Bulgarian samples and their significantly higher genetic diversity imply that gene flow occurred among different regions of Bulgaria during the last ice age.

Comparative Technological Study of the Tobacco of Burley Variety Group Grown in Bulgaria

ABSTRACTIt is known that the variation in tobacco indicators is mainly determined by the harvest belt (the biological factor) and the crop (the climatic factor), and less by the region and microregion of growing (soil-climatic and agrobiological factors). It has been established in a research of the quality of Burley tobacco, produced in different regions in Bulgaria that the Bulgarian Burley tobacco corresponds to the type according by general quality, but it has some specific peculiarities due to the specific conditions of growing. The purpose of the present study is the comparative technological investigation of the tobacco of Burley variety group, grown in different regions in Bulgaria, with the view of establishing the typical for the variety high quality. The samples taken from different regions of the country have been analyzed with respect to the main technological indicators, describing their quality. The results obtained show that there are no clearly expressed differences as to the quality between the Burley tobacco variety produced in the different regions in Bulgaria. By complex quality estimation they suit the requirements for this type of tobacco, and more specifically with respect to the objective chemical indicators. When applying appropriate agricultural equipment, as well as under favourable climatic conditions (crop), they possess qualities that meet the purchasers' requirements towards this tobacco type according to its consumption.

Efficacy of parenteral administration of ivermectin in the control of strongylidosis in donkeys

Investigations into the efficacy of parenteral ivermectin (Pandex) administration for strongylidosis control in donkeys were carried out. The preparation was applied subcutaneously at a dose of 0.2 mg/kg (1 ml/50 kg body weight). One day prior to the treatment and 14 days post-treatment, individual coprological samples were obtained for faecal nematode egg counts and larval culture. The study was performed on 263 donkeys originating from different regions of Bulgaria. Prior to the treatment and 20 days after that, blood samples were obtained from 64 previously infected animals for monitoring of changes in eosinophil leukocyte counts. The subcutaneous application of ivermectin had an efficacy of 96% in terms of reduction of faecal egg counts. In 92.2% of infected donkeys, a complete reduction of faecal eggs count occurred (0 eggs per gram of faeces epg), whereas in the remaining 7.8% of the infected donkeys, the egg counts were reduced by 72%. The reduction in faecal egg counts did not result in changes in eosinophil counts. The results obtained as well as the lack of local changes after the subcutaneous application of ivermectin in donkeys allow us to recommend its use for control of strongyles in donkeys.

Technological Study on Tobaccos of Basmi Group Variety Grown in Different Regions of Bulgaria

ABSTRACTThe quantities of the origins that are being produced, the varieties of traditionally well-known high quality, respectively, for the time being cannot meet the demands of the tobacco processing companies and of the large international cigarette manufacturers, who purchase these tobaccos. Improvement of zoning and variety re-structuring may lead to the achievement of certain enlargement of the origins. Thus, it will increase the opportunities to provide stable quantities of similar quality tobaccos, of which uniform export batches are prepared. This study aims at making a technological assessment of the quality indicators of varieties of Krumovgrad origin, grown in certain regions in Bulgaria and comparing them to those grown in the traditional regions or the so-called “typical” tobaccos of such sub-group. The comparison of tobacco quality was made on the basis of the assessment of the technological indicators: physical indicators; chemical composition of tobacco and tobacco smoke; “image” taking; organoleptic assessment. It was established keeping of the general character in the expression of the quality of the different varieties of Krumovgrad sub-group variety, grown in the studied regions and as a matter of fact, their assessment didn't demonstrate any significant differences. The influence of the genetic factor (variety) is clearly expressed with the varieties of the origin, i.e. it proved to be adaptive to the new conditions.

Technological Study on Tobaccos of Basmi Group Variety Grown in Different Regions of Bulgaria

ABSTRACTThe need from increasing and stabilization of the production of tobacco origins and varieties of high market demands made us study the opportunities to extend their production. It also refers to Dzhebel origin, known for its traditional high quality. This study aims at making a technological assessment of the quality indicators of varieties of Dzhebel origin, grown in certain regions in our country and comparing them to those grown in the traditional regions or the so-called “typical” tobaccos of such sub-group variety. The study was made on the basis of the assessment of the technological indicators, describing their quality: physical indicators; chemical composition of tobacco; tobacco smoke composition; spectrophotometric assessment; expert's assessment; taste assessment. More significant differences are established between the compared samples at the expert's assessment, as the tobaccos from the “typical” regions prove to have better indicators. When compared to the varieties from “Krumovgrad” origin, the influence of the genetic factor (variety) is less expressed with the varieties from “Dzhebel” origin, i.e. it appears less adaptive to the new conditions.

Ecological distribution and species diversity of Aegilops L. genus in Bulgaria

The genus Aegilops has an important potential utilization in wheat improvement because of its resistance to different biotic and abiotic stresses and close relation with the cultivated wheat. Therefore, a better knowledge of the eco-geographical distribution of Aegilops species and their collection and conservation are required. A total of 297 Aegilops accessions representing nine (five tetraploid and four diploid) species were collected in different regions of Bulgaria, and the ecological characteristics of the 154 explored sites were recorded. The distribution of the diploid species (Ae. caudata L., Ae. speltoides Tausch, Ae. umbellulata Zhuk. and Ae. comosa Sibth. and Sm.) was limited to specific environments in south-central Bulgaria. Tetraploid species were present in harsher environments than diploid species and showed wider adaptation and distribution. Species–environment relationships were analysed by considering the worldwide distribution of the species and their physiological resistance to abiotic stress. Aegilops cylindrica Host was more frequently found in northern Bulgaria and at high altitudes. Its distribution was closely related to its tolerance to low temperatures. Aegilops geniculata Roth and Ae. neglecta Req. ex Bertol. were absent in the north of Bulgaria, but widely distributed in low rainfall areas. Aegilops neglecta, more frost resistant than Ae. geniculata, was present at higher altitude. Aegilops biuncialis Vis. and Ae. triuncialis L. showed adaptation to a wide range of climatic conditions. The study of Aegilops species ecology and distribution in Bulgaria provided useful information for the future collection and for the genetic resource management in this region.

Characterisation of Collagenolytic Enzymes Produced by Thermophylic Actinomycetes

ABSTRACTThe aim of the present investigation was to characterize enzymes, produced by extremophilic microorganisms in soil samples, collected from different regions in Bulgaria. The cultivation conditions for obtaining high yield of collagenolytic activity were optimized for two active strains—A 35 and E 15. The molecular mass of the active fractions in the cultural liquid of both strains was determined by means of gel chromatography on Sephadex G-100 and were in the range from 40 to 140 kDa. The proteolytic enzymes were stable against high ethanol concentrations, which allows an effective elimination of different byproducts (pigments, nutrient medium components and metabolites). The electrophoretic patterns show a certain isomorphism of the fractions. The comparison with clostridiopeptidase A, as well as the inhibitory analysis show that these enzymes might be considered as “collagenase-like” enzymes. Preliminary experiments show that they could be applied for pre-treatment of collagen-rich raw materials, e.g. in the pelt industry.

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria I: monitoring points and bioaccumulation features

Data on liver and body copper, zinc, lead, and cadmium content of small mammals (rodents and insectivorous) were collected and analyzed. Data comparisons were performed in two aspects: (1) points and years of monitoring; (2) monitor species bioaccumulations. Specific bioaccumulation features were observed in some of the monitor species. A method for comparative evaluation of heavy metal loads in the different species is proposed using data for liver and body contamination. The loads of Clethrionomys glareolus and Apodemus flavicollis were compared, and the data are in agreement with data from other authors in Central Europe. A correlation between heavy metal content in the food and liver of snow vole was established. The data demonstrate that two of the regions investigated in Rila Mountain National Park could be assumed to be background locations. Some possible reasons for the heavy metal contamination of the low-altitude region in Rila are discussed. Not very significant pollution was observed around industrial facilities. Correlations between heavy metal levels in zoomonitors and meteorological factors were established.

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria II: chromosomal aberrations and blood pathology

Heavy metal content was monitored in small mammals inhabiting mountain ecosystems and two industrial polluted regions in Bulgaria. Rodents ( Microtus arvalis, M. rossiaemeridionalis, Clethrionomys glareolus, Pitymys subterraneus, Chionomys nivalis, Apodemus flavicollis, A. sylvaticus, and Mus macedonicus) were used as zoomonitors. Pathological changes in chromosome status, hematological indices, and blood cell morphology were analyzed in the context of heavy metal bioaccumulation. Significant correlations were obtained between the heavy metal load of zoomonitors and the frequency of chromosomal aberrations and pathological changes in erythrocytes (mainly micronuclei and basophilic granulations). It is suggested that mercury is a strong damaging factor for chromosomes and red blood cell apparatus.

DURABLE RESISTANCE TO BROOMRAPE (Orobanche cumana Wallr. / Orobanche cernua Loefl.) IN SUNFLOWER / RESISTENCIA CONSTANTE A LA OROBANCA (Orobanche cumana Wallr./Orobanche cernua Loefl.) EN EL GIRASOL / RÉSISTANCE DURABLE À L’OROBANCHE (Orobanche cumana Wallr./Orobanche cernua Loefl.) CHEZ LE TOURNESOL

SUMMARY Six cultivars and one hybrid were evaluated for resistance to broomrape in the period 1988-1999. It was found that the resistance varied in the range from 0 to 100%. The evaluation was carried out under greenhouse conditions. Infestations were induced by mixed broomrape populations collected from different regions in Bulgaria. Different lines obtained from three cultivars, Progress, Oktjabr (Russia) and Vega (Bulgaria), and the hybrid Sorem 80 (Romania) showed stable resistance (80-100%) after ten years of evaluation, in spite of the occurrence and distribution of new races (D+E) of the parasite in Bulgaria.