The role of evolutionary interactions between intracellular endosymbiont (Wolbachia) and phytoplasma (Flavescence dorée) on fitness components and evolution of mitochondrial DNA in natural populations Dictyophara europaea

Dictyophara europaea je široko rasprostranjena i ekonomski značajna cikada koja kao alternativni vektor Flavescence dorée (FD) fitoplazme, učestvuje u prenošenju bolesti u vinogradima Evrope. Sprovedena epidemiološka istraživanja su ukazala na postojanje populacija D. europaea sa veoma visokom stopom FD-infekcije, Wolbachia-inficiranih populacija sa niskom stopom FD-infekcije (DeWo+) i odsustvo Wolbachia u populacijama sa visokom stopom FD-infekcije (DeWo-). Ispitivano je nekoliko mogućih uzroka raličite stope infekcije vektora: i) populaciono-genetičke karakteristike D. europaea i korelacija sa Wolbachia infekcijom, ii) efekat Wolbachia na komponente adaptivne vrednosti laboratorijske kolonije DeWo+, i iii) stopa inficiranosti prirodnog biljnog rezervoara FD fitoplazme i razlike u genotipovima fitoplazme u nisko- i visokoinficiranim populacijama. Genotipizacijom mitohondrijskog COI gena evidentiran je smanjen genetički diverzitet DeWo+ u poređenju sa DeWo- populacijama i različita evolucija fiksiranih haplotipova. Multilokusnom genotipizacijom Wolbachia izolata identifikovan je isti soj, wEur, u svim DeWo+ populacijama. Diverzitet FD fitoplazme nije bio u korelaciji sa različitom stopom inficiranosti vektora. Utvrđeno je da Wolbachia-infekcija nema direktnog efekta na adaptivnu vrednost D. europaea. Podaci iz prirodnih populacija D. europaea ukazuju na kompeticiju Wolbachia i FD fitoplazme: populacije koje su u niskoj stopi inficirane FD fitoplazmom su Wolbachia-inficirane i vice versa.Dictyophara europaea is widespread planthopper of economic importance, acting as an alternative vector of the Flavescence dorée (FD) phytoplasma disease of grapevine in European vineyards. Epidemiological studies have revealed D. europaea populations that are heavily FD-infected, as well as populations with low FD-infection rates that are naturally infected with Wolbachia (DeWo+), and highly FD-infected populations in the absence of Wolbachia (DeWo-).Several possible causes of differences in vector infection rates were examined: i) population genetic characteristics of D. europaea and their correlation with Wolbachia infection, ii) Wolbachia effects on fitness components of DeWo+ laboratory colony, and iii) the rate of reservoir plant FD-infection and differences in FD genotypes harboured by low and high infected vector populations. Genotyping of mitochondrial COI loci showed lower genetic diversity level in DeWo+ than in DeWo- populations of and divergent evolution of fixed haplotypes. Multilocus genotyping of Wolbachia revealed that all DeWo+ populations were infected with the same strain (i.e. wEur). Genetically diversified FD phytoplasma had no direct influence on vector infection rates. No evidence of direct fitness effects on D. europaea was registered with regard to Wolbachia infection status. Field data and the observed negative correlation between FD-infection and Wolbachia-infection rates, indicate that Wolbachia compete with FD phytoplasma within the host insect D. europaea

Rasprostranjenje alder yellows fitoplazme na crnoj i beloj jovi (Alnus glutinosa i Alnus incana) u Srbiji

Alder yellows (AldY) phytoplasma associated with common alder (Alnus glutinosa) and grey alder (A. incana) belongs to the ribosomal RNA group16SrV. This phytoplasma is closely related to the Flavescence dorée (FD) phytoplasma, a quarantine pathogen of economic importance that affects vineyards of southern Europe including Serbia. To date, alder yellows phytoplasma has been reported in many European countries including France, Germany, Switzerland, Austria, Italy and the Baltic region. Infected alders are exhibiting symptoms such as leaf yellowing, small leaves, reduced foliage, or sometimes they remain symptomless. To investigate occurrence and distribution of this phytoplasma, a survey was conducted on a wide territory of Serbia. Results confirmed wide distribution of alder yellows phytoplasma in Serbia in both symptomatic and asymptomatic trees. From the 72 plants sampled, 54 were positive for the presence of phytoplasmas. RFLP profiles of the 16S rRNA gene indicated presence of 16SrV-C phytoplasma subgroup. Further characterization by PCR-RFLP analysis of the ribosomal protein gene operon of all phytoplasma positive isolates tested confirmed presence of the 16SrV-C phytoplasma subgroup. Implication of the wide distribution of AldY phytoplasma to the epidemiology of FD phytoplasma as well as disease management are discussed.Alder yellows (AldY) fitoplazma koja je u asocijaciji sa crnom jovom (Alnus glutinosa) i belom jovom (A. incana) pripada 16SrV ribozomalnoj grupi fitoplazmi. Ova fitoplazma je srodna fitoplazmi zlatastog žutila vinove loze Flavescence dorée (FD), koja je karantinski patogen od ekonomskog značaja u vinogradima južne Evrope uključujući i Srbiju. Do sada je prisustvo alder yellows fitoplazme utvrđeno u mnogim evropskim zemljama uključujući Francusku, Nemačku, Švajcarsku, Austriju, Italiju i Baltički region. Inficirane jove ispoljavaju simptome žutila listova, malih listova, redukcije lisne mase, ili ponekad ne ispoljavaju simptome inficiranosti. U cilju utvrđivanja prisustva i rasprostranjenja ove fitoplazme na široj teritoriji Srbije, sprovedeno je uzorkovanje simptomatskih i asimptomatskih jova. Rezultati istraživanja su potvrdili široku distribuciju alder yellows fitoplazme u Srbiji i prisustvo fitoplazme kako u simptomatskim tako i u asimptomatskim stablima. Od ukupno 72 uzorkovane biljke, 54 su bile inficirane fitoplazmom. Analizom RFLP profila 16S rRNK gena utvrđeno je prisustvo 16SrV-C podgrupe fitoplazmi. Dalja karakterizacija PCR-RFLP analizom operona ribozomalnih proteina svih pozitivnih izolata potvrdila je prisustvo 16SrV-C podgrupe fitoplazmi. U diskusiji je istaknut značaj širokog rasprostranjenja AldY fitoplazme i uticaja na epidemiologiju FD fitoplazme kao i na kontrolu bolesti

Tuta absoluta (Meyrick, 1917) (Lepidoptera, Gelechiidae) - nova štetočina paradajza u Srbiji

Tomato leaf miner Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), a devastating pest of tomato originating from South America has been recorded in Serbia on three localities: in tomato main greenhouse and open field production area located in the vicinity of town Leskovac (South Serbia), in surroundings of the village Donji Vrtogoš (near town Vranje, South Serbia) and in a greenhouses complex in Kraljevci (60 km west of Belgrade). The presence of T. absoluta was confirmed by morphological and molecular study of the collected specimens.Prisustvo lisnog minera paradajza Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), opasne štetočine poreklom iz Južne Amerike, utvrđeno je na tri lokaliteta u Srbiji: u plastenicima i poljima u okolini Leskovca (južna Srbija), u okolini sela Donji Vrtogoš (u blizini Vranja) i u kompleksu plastenika u selu Kraljevci (60 km zapadno od Beograda). Identifikacija T. absoluta je izvršena morfološkim i molekularnim analizama sakupljenih uzoraka

Drosophila suzukii (Matsumura, 1931) (Siptera: Srosophilidae) - nova invazivna vrsta u Srbiji

During October and November 2014, a survey was conducted in order to establish the presence of the invasive pest Drosophila suzukii (Matsumura, 1931) on the territory of Serbia. Survey revealed the presence of this fly in four districts (Rasinski, Mačvanski, Raški and Pčinjski), in sampled raspberry and blackberry ripe fruits, as well as in common fig and grape. Collected fruits were used for the rearing of Drosophilid larvae to adults, which were subsequently subjected to morphological and molecular characterization. The presence of D. suzukii was confirmed in all surveyed districts, as well as in Zemun (City of Belgrade). This is the first report of the highly invasive fruit pest D. suzukii on the territory of Serbia.Tokom oktobra i novembra 2014. godine, sprovedena su istraživanja u cilju utvrđivanja prisustva i rasprostranjenja invazivne štetočine Drosophila suzukii (Matsumura, 1931) na teritoriji Srbije. Prisustvo ove mušice je utvrđeno u okviru četiri okruga (Rasinski, Mačvanski, Raški, Pčinjski), u uzorkovanim plodovima maline, kupine, smokve i grožđa. Iz plodova su odgajene Drozofilidne larve do adulta koji su zatim analizirani morfološki i molekularno. Prisustvo D. suzukii je utvrđeno na svim lokalitetima u okviru četiri okruga, kao i na teritoriji grada Beograda (Zemun). Ovo je prvi nalaz invazivne štetočine voća D. suzukii na teritoriji Srbije

Should they stay, or should they go: drop out in higher education

Dropping out of higher education is a global phenomenon which affects virtually all universities. The main aim of this research is to determine the factors which have the most predictive value for students’ satisfaction with their studies and dropout intentions. The research was conducted on the sample of 673 students who completed a self-description questionnaire which included 22 dimensions of students’ perceptions of their studies. Based on a two-step cluster analysis, we have identified the group of students at risk of dropout. ANOVA has shown that the two groups differ on almost all investigated dimensions. Individual-related factors, developed in a specific context, are the main predictors of students’ dropout from higher education. Understanding of these factors can improve the system of early detection of students at risk of dropping out

Dropout at university level in Serbia: analysis of measurement, research findings, services and prevention measures

Dropout in higher education attracts great attention due to serious effects on an individual and on society. This is an exploratory study aimed at: analysing dropout measurement and tracking in the Serbian higher education, reviewing studies on dropout causes, and identifying available services and prevention measures. Various techniques are used to achieve these goals (statistics analysis, literature review, qualitative content analysis). Our results show that: 1. There are no accepted dropout definitions nor official statistics, but some rate estimate could be given; 2. Research is not systematic, but covers three major dropout factors (individual, socio-demo-graphic, studying conditions); 3. Services are sporadic and not visible enough; 4. Legislation reveals state interest in promoting higher education, but implemented measures are not adequate enough. We see establishment of the Unified Education Information System as an important step in precise dropout measurement. There is a need for flexible studying routes and increased financial support orientated more towards vulnerable student groups. International studies highlight the importance of intensification of teacher-student and peer interaction built in modern student-centred teaching practice. At the end, we advocate creating a new educational policy by combining two major frameworks in this field and relying on inclusive research

Morphology versus DNA barcoding: two sides of the same coin. A case study of Ceutorhynchus erysimi and C. contractus identification

Genotyping of 2 well-known weevil species from the genus Ceutorhynchus (Coleoptera: Curculionidae) distributed in west Palearctic, C. erysimi and C. contractus, revealed phenotype versus genotype inconsistencies in a set of 56 specimens (25 C. erysimi and 31 C. contractus) collected from 25 locations in Serbia and Montenegro. An analysis of the mitochondrial cytochrome oxidase subunit I gene (COI), widely used as a barcoding region, and a nuclear gene, elongation factor-1 alpha (EF-1 alpha), revealed stable genetic divergence among these species. The average uncorrected pairwise distances for the COI and EF-1 alpha genes were 3.8%, and 1.3%, respectively, indicating 2 genetically well-segregated species. However, the genetic data were not congruent with the phenotypic characteristics of the studied specimens. In the first place, C. erysimi genotypes were attached to specimens with phenotypic characteristics of C. contractus. Species-specific PCR-RFLP assays for the barcoding gene COIwere applied for themolecular identification of 101 additional specimens of both morphospecies (33 C. erysimi and 68 C. contractus) and were found to confirm this incongruity. The discrepancy between the genetic and morphological data raises the question of the accuracy of using a barcoding approach, as it may result in misleading conclusions about the taxonomic position of the studied organism. Additionally, the typological species concept shows considerable weakness when genetic data are not supported with phenotypic characteristics as in case of asymmetric introgression, which may cause certain problems, especially in applied studies such as biological control programs in which the biological properties of the studied organisms are the main focus

Experimental and molecular evidence of Reptalus panzeri as a natural vector of bois noir

Bois noir (BN) is an economically important grapevine yellows disease induced by the stolbur phytoplasma and principally vectored by the cixiid Hyalesthes obsoletus. This study addresses the involvement of other planthoppers and/or leafhoppers in BN epidemics in the South Banat district of northeastern Serbia, by performing transmission experiments and multilocus typing of stolbur phytoplasma isolates to determine the vector-related characteristics of the disease. Transmission trials were conducted with adults of two cixiid congeners, Reptalus panzeri and R.quinquecostatus, which were found to harbour stolbur phytoplasma in the vineyards under study. A molecular characterization of stolbur phytoplasma isolates was performed by sequence analysis and/or RFLP typing of the two housekeeping genes tuf and secY and the two membrane proteins stamp and vmp1. Transmission trials with naturally infected R.panzeri adults from either the BN-infected vineyards or maize redness (MR)-affected maize fields revealed a high stolbur phytoplasma transmission efficiency to grapevines. In contrast, experiments conducted with stolbur-positive R.quinquecostatus originating from BN-infected vineyards, provided no evidence for a vector role of this species. Seven stolbur phytoplasma genotypes, all of which were tuf-b types, were detected among the grapevine- and insect-associated field samples according to the tuf/secY/vmp1/stamp typing. STOLg was the genotype most frequently found in naturally infected grapevine (42%), as well as R.panzeri originating from the vineyards (85%) and maize fields (98%). The same genotype was found in all experimental plants inoculated by R.panzeri, confirming its vectorship of the disease

Symptomatology, (Co)occurrence and Differential Diagnostic PCR Identification of ‘Ca. Phytoplasma solani’ and ‘Ca. Phytoplasma convolvuli’ in Field Bindweed

Field bindweed (Convolvulus arvensis) is one of the major natural plant hosts and reservoirs of ‘Candidatus Phytoplasma solani’ (‘Ca. P. solani’), the causal agent of plant diseases in diverse agricultural crops, including Bois noir (BN) disease of grapevine. Phylogenetically, the most closely related phytoplasma to ‘Ca. P. solani’, the ‘Ca. P. convolvuli’, induces disease in field bindweed that is known by its symptoms as bindweed yellows (BY). The occurrence, coinfection and symptoms association of the two phytoplasmas in shared host plants were the subject of this study. Specific primers for the amplification of the elongation factor Tu gene (tuf ) were developed for the identification of ‘Ca. P. convolvuli’ (by conventional nested PCR), as well as primers for simultaneous detection of ‘Ca. P. solani’ and ‘Ca. P. convolvuli’ by duplex SYBR Green real-time PCR. Among symptomatic bindweed plants, 25 and 41% were infected with a single phytoplasma species, ‘Ca. P. solani’ and ‘Ca. P. convolvuli’, respectively, while 34% were infected with both phytoplasmas. None of the non-symptomatic control plants carried phytoplasma, while non-symptomatic plants from our previous epidemiological studies in BN-affected vineyards were confirmed to be infected solely with ‘Ca. P. solani’. Stamp gene typing revealed Rqg50 and Rqg31 ‘Ca. P. solani’ genotypes in plants coinfected with ‘Ca. P. convolvuli’, while three diverse genotypes (Rqg50, GGY and Rpm35) were identified in a single locality with symptomatic bindweeds infected solely with ‘Ca. P. solani’. Variations in symptoms and their association with each of the phytoplasmas are described and documented. The symptom of bushy appearance could be single out as specific for ‘Ca. P. convolvuli’ infection, while occurrence of ‘Ca. P. solani’ could not be unequivocally associated with specific alterations in infected bindweeds. The results are discussed in the context of the epidemiological and ecological complexity of ‘Ca. P. solani’-induced diseases and the relationship between the two phytoplasma relatives in shared host plant