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Wolbachia infection in natural populations of Dictyophara europaea, an alternative vector of grapevine Flavescence doree phytoplasma: effects and interactions
No full textThe European lantern fly, Dictyophara europaea, is an alternative vector of the Flavescence doree phytoplasma (FDp) disease of grapevine in European vineyards, enabling infection initiation from wild reservoir compartment (Clematis vitalba). Heretofore recorded rate of D. europaea FDp-infection has been very low (3%), making it less epidemiologically significant than would be expected based on reservoir plant infection rate (30%). In this study we present findings on a heavily FDp-infected D. europaea population ( gt 60%), on the natural Wolbachia infection of populations with low FDp-infection rates (DeWo+) and on Wolbachia absence in highly FDp-infected population (DeWo-). We examine several possible causes underlying the differences in vector infection rates: (a) population genetic characteristics of D. europaea and correlation with Wolbachia strain wEur natural infections, (b) Wolbachia effects on fitness components of DeWo+ laboratory colony and (c) rate of reservoir plant FDp-infection and differences in FDp genotypes harboured by low and highly infected vector populations. The vector genetic diversity level was found to be lower in DeWo+ than in uninfected individuals and to exhibit a different evolution of fixed haplotypes. All DeWo+ populations were infected with the same strain of wEur. The FDp was found to be genetically diversified (five genotypes) but had no relation to infection rates. We did not find evidence of fitness upgrades with regard to Wolbachia infection status. Although more experimentation is needed, it seems that Wolbachia confers protection against FDp or is in competition with FDp according to the observed correlations: low FDp-infected vector populations are infected with Wolbachia and vice versa
Biochemical changes in Oenothera biennis plants infected by 'Candidatus Phytoplasma solani'
No full textThe aim of the present paper was to study the response of Oenothera biennis L. to 'Candidatus Phytoplasma solani' (Stolbur) infection by analyzing total sugars, polyphenols, photosynthetic pigments content and the antioxidant capacity in leaves and roots of healthy and infected plants. The infection caused a significant increase in peroxidation of lipids, phenylalanine ammonia-lyase activity, total sugar, polyphenols and anthocyanins content (2.8, 2.6, 1.8, 1.4, 6.8 fold, respectively), as well as a decrease in photosynthetic pigments (2-6 fold) and total flavonoids (1.5 fold) in the leaves of Oe. biennis. Changes in these parameters were insignificant in the roots except for the total polyphenols content that was 2.7 times higher in the infected ones. Reduced gluthatione content in both tested organs was not affected by the infection (3.7 and 1.7 mu mol/g fresh weight of leaves and roots, respectively). The elevated content of total sugars, flavonoids and polyphenols, as well as the reduction of photosynthetic pigments and anthocyanins in infected plants are indicative of changes in the metabolism of Oe. biennis affected by the Stolbur phytoplasma. In addition to reduction of chlorophyll and carotenoids, the phytoplasma accelerated leaf senescence. Plants responded to the infection via enhanced superoxide anion scavenging, even though this reaction did not prevent, apparently, membrane damage in analysed leaves. This investigation presents new data on the effect of a phytoplasma infection on its host
Ispitivanje karakteristika ratarskih prskalica u Rasinskom okrugu
No full textIn agricultural production, pests and diseases of agricultural crops, as well as weed plants, cause significant losses in the yield and quality of agricultural products. One of the most effective ways of fighting is the use of a wide range of chemicals called pesticides. In accordance with the EU Directives 2009/128/EC and 2006/42/EC underlying the standard EN 13790, the Plant Protection Administration of the Ministry of Agriculture and the Environment of the Republic of Serbia has established a framework for the control of sprayers and mist blowers. Maintaining sprayers for pesticide application in a good state of repair and proper working order reduces their harmful effects on human health and the environment. The nozzle is one of the most important parts of plant protection machines, responsible for the following major functions: delivery of a given amount of liquid in a unit of time, dispersion of the liquid by making droplets of different sizes and forming a stream of a particular shape. Testing of the working safety of sprayers and nozzles was carried out in accordance with the European Standard EN 13790 which specifies the methods and equipment for inspection. The flow rate of nozzles was measured by an S001 nozzle tester (AAMS-Salvarani, Belgium). The measuring equipment used for testing the pesticide application device can accurately determine any deviation and irregularity in the application.U poljoprivrednoj proizvodnji, štetočine i bolesti poljoprivrednih kultura, kao i korovske biljke svake godine prouzrokuju značajne gubitke u prinosu i kvalitetu poljoprivrednih proizvoda. Jedan od najefikasnijih načina borbe jeste primena brojnih i različitih hemijskih sredstava, koja se nazivaju opštim nazivom pesticidi. U skladu sa Direktivama Evropskog parlamenta 2009/128/EC i 2006/42/EC, kojima je osnova standard EN 13790, koji propisuje obavezni pregled mašina za zaštitu bilja, Uprava za zaštitu bilja Ministarstva poljoprivrede i životne sredine Republike Srbije uspostavlja okvir za kontrolu sistema prskalica i orošivača. Upotrebom tehnički ispravnih i kontrolisanih ratarskih prskalica za primenu pesticida smanjuje se njihov štetni uticaj na zdravlje ljudi i životnu okolinu. Jedan od najznačajnijih delova mašina za zaštitu bilja predstavljaju rasprskivači. Oni obavljaju najvažnije funkcije, kao što su: propuštaju zadate količine tečnosti u jedinici vremena, raspršuju tečnost praveći kapljice odgovarajućih veličina i formiraju mlaz odgovarajućeg oblika. Testiranje radne ispravnosti prskalice i rasprskivača vršeno je u skladu sa evropskim normativom EN 13790, koji propisuje metode i opremu kojom se obavlja inspekcija. Protok rasprskivača je meren pomoću ispitivača pojedinačnih rasprskivača S001 belgijskog proizvođača 'AAMS-Salvarani'. Primenom merne opreme za ispitivanje ispravnosti rada uređaja za primenu pesticida, merenjem je moguće tačno ustanoviti svako odstupanje i nepravilnost u radu. Dobijeni rezultati ukazuju na to da postoje značajna odstupanja ispitivanih parametara
Antifungalna aktivnost hitosana prema Alternaria alternata i Colletotrichum gloeosporoides
No full textChitosan and its derivatives have been reported as a promising alternative for control of postharvest fungal pathogens. The objective of this study was to evaluate in vitro and in situ antifungal activity of chitosan against Alternaria alternata and Colletotrichum gloeosporioides isolated from decayed apple fruits. The fungi were tested in vitro using PDA medium with three concentrations of chitosan (1, 2 and 3 mg/ml). Fungal growth of the test pathogens was significantly affected by all chitosan doses (P lt 0.05) after 7 days of incubation at 25°C. Water solution of 3 mg/ml of chitosan inhibited completely the conidial germination of A. alternata and C. gloeosporioides after 18 h incubation at 25°C. The results obtained from biocontrol assay indicate that the inhibition of postharvest decay of A. alternata and C. gloeosporioides was significantly influenced by chitosan concentrations. Disease incidence in chitosan-treated fruit after 7 days incubation at 25°C was significantly lower than in the positive control for both fungi tested (P lt 0.05). A. alternata and C. gloeosporioides used in this study were progressively inhibited in vitro and in situ with increasing concentrations of chitosan from 1 to 3 mg/ml.Istraživanja pokazuju da su hitosan i njegovi derivati dobra alternativa u kontroli skladišnih fitopatogenih gljiva. Cilj ovog rada bio je da ispita antifungalnu aktivnost hitosana prema Alternaria alternata i Colletotrichum gloeosporoides, izolovanih sa inficiranih plodova jabuke, u in vitro i in situ uslovima. Rast gljiva je testiran in vitro koristeći PDA podlogu sa različitim koncentracijama hitosana (1, 2 i 3 mg/ml). Porast oba patogena je bio značajno smanjen (P lt 0.05) u svim koncentracijama hitosana nakon 7 dana inkubacije na 25°C. Vodeni rastvor hitosana koncentracije 3 mg/ml je u potpunosti inhibirao klijanje konidija A. alternata i C. gloeosporoides nakon inkubacije od 18 sati na temperaturi od 25°C. Rezultati ogleda in situ ukazuju da inhibicija propadanja plodova inficiranih sa A. alternata i C. gloeosporoides zavisi od koncentracije rastvora hitosana. Pojava bolesti na plodovima jabuka tretiranih rastvorom hitosana nakon 7 dana inkubacije na 25°C bila je značajno smanjena za obe vrste gljiva (P lt 0.05) u odnosu na pozitivnu kontrolu. Rast A. alternata i C. gloeosporoides je bio progresivno inhibiran in vitro i in situ sa povećanjem koncentracije rastvora hitosana, od 1 do 3 mg/ml
Genetic diversity and pathogenicity of Pseudomonas syringae pv. aptata isolated from sugar beet
No full textPseudomonas syringae pv. aptata is the causal agent of bacterial leaf spot disease of sugar beet (Beta vulgaris). During 2013, 250 samples were collected from leaf lesions with typical symptoms of bacterial leaf spot in commercial fields of sugar beet in Serbia, and 104 isolates of P.syringae pv. aptata were obtained. Identification and characterization was performed using biochemical, molecular and pathogenicity tests. Identification included LOPAT tests and positive reactions using primers Papt2F and Papt1R specific for P.syringae pv. aptata. Repetitive (rep) sequence-based PCR typing with ERIC, REP and BOX primers revealed high genetic variability among isolates and distinguished 25 groups of different fingerprinting profiles. Pulse-field gel electrophoresis (PFGE) and multilocus sequence analysis (MLSA) of representative isolates showed higher genetic variability than in rep-PCR analysis and distinguished three and four major genetic clusters, respectively. A pathogenicity test performed with 25 representative isolates on four cultivars of sugar beet confirmed the occurrence of leaf spot disease and showed correlation between the most aggressive isolates and the genetic clusters obtained in MLSA. All these findings point to the existence of several lines of P.syringae pv. aptata infection in Serbia that are genetically and pathologically different
First Report of Pseudomonas syringae pv. syringae Associated with Bacterial Blossom Blast on Apple (Mains pumila) in the United States
No full textA new Aceria species (Acari: Trombidiformes: Eriophyoidea) from West Asia, a potential biological control agent for the invasive weed camelthorn, Alhagi maurorum Medik. (Leguminosae)
No full textA new species of eriophyoid mite Aceria alhagi n. sp. inhabiting the weed Alhagi maurorum Medik., is described from the type locality in Iran, but it was also collected from Uzbekistan, Turkey and Armenia. This mite causes changes of the leaves and inflorescence. Infested plants develop cauliflower- like galls on the inflorescence and leaves deforming the reproductive structures and inhibiting seed production. The potential reduction in seed set suggests that this mite could constitute a potential biological control agent against this noxious weed. To investigate intraspecific variability between A. alhagi n. sp. populations from Iran, Turkey and Armenia, we analysed molecular sequences of the mitochondrial cytochrome oxidase subunit I (mtCOI). These results indicated that there are no significant intraspecific divergences among populations of A. alhagi n. sp. from the five different localities in three West Asia countries. This finding can be used in the future research of certain mite populations as biological control agent
A new species of Aculus mite (Acari: Eriophyidae), a potential biocontrol agent for Australian swamp stonecrop, Crassula helmsii (Crassulaceae)
No full textA new, gall-forming eriophyoid mite species is described from Australia. Aculus crassulae sp. nov. was found causing significant leaf deformation in Crassula helmsii (Kirk) Cockayne (Crassulaceae), a semi-aquatic, succulent plant. Native to Australia and New Zealand, this plant is now a highly invasive weed in the United Kingdom and Western Europe. The host specificity of the new mite species, and damage caused to the host plant, infer its potential to be a valuable biological control agent in countries where Australian swamp stonecrop is threatening native flora. The species description provided here, which also includes a revised diagnosis for the genus Aculus, incorporates line drawings and scanning electron micrographs (SEM). This is supplemented by a partial mitochondrial gene sequence of cytochrome c oxidase subunit I (mtCOI) and the sequence was compared with Aculus amygdali Xue & Hong and Aculus ichnocarpi (Ghosh & Chakrabarati) available in the NCBI database. Pairwise comparison of mtCOI sequences between A. crassulae sp. nov. and two congeneric species revealed 22.6% and 23.1% genetic divergence, respectively
Revision of the European Lysiphlebus species (Hymenoptera: Braconidae: Aphidiinae) on the basis of COI and 28SD2 molecular markers and morphology
No full textMembers of the genus Lysiphlebus Foerster are medium-sized endoparasitoid aphidiine wasps with over 30 species distributed worldwide. They attack numerous aphid hosts, and some species are important biological control agents. All European Lysiphlebus species are revised based on sequence information from the mitochondrial COI barcoding gene and the nuclear 28SD2 gene, morphological traits, and on information about their host specificity. The taxonomic status of 13 European Lysiphlebus species is confirmed, while 11 are redescribed and illustrated. The following four Lysiphlebus species are synonymized: L. melandriicola Stary, 1961 [= L. fabarum (Marshall, 1896)], L. hirtus Stark, 1985 (= L. confusus Tremblay & Eady, 1978), L. hispanus Stary, 1973 (= L. desertorum Stary, 1965), and L. safavii Stary, 1985 (= L. hirticornis Mackauer, 1960). Two new Lysiphlebus species are described: L. volkli sp.n. and L. brachycaudi sp.n. Our results, based on both COI and 28SD2, confirm the existence of three monophyletic species groups within the genus: (1) the 'fabarum' group, which includes L. fabarum, L. cardui (Marshall, 1896), L. confusus, L. hirticornis, L. brachycaudi sp.n., and L. volkli sp.n.; (2) the 'testaceipes' group, which includes L. testaceipes (Cresson, 1880), L. orientalis Stary & Rakhshani, 2010, L. fritzmuelleri Mackauer, 1960, L. balcanicus Stary, 1998, L. desertorum, [and probably L. dissolutus (Nees, 1811)]; and (3) the 'alpinus' group, consisting solely of L. alpinus Stary, 1971. Geometric morphometrics of fore wing shape proved to be a powerful tool to delineate sibling species within the fabarum' group. We were able to confirm for the first time sexual lines of L. cardui and L. confusus. Furthermore, an additional potentially asexual Lysiphlebus taxon in Europe is revealed based on the discovery of an asexual line of L. volkli sp.n. in Iran. An illustrated key for identification of the European Lysiphlebus species is provided
