When a Palearctic bacterium meets a Nearctic insect vector: Genetic and ecological insights into the emergence of the grapevine Flavescence dorée epidemics in Europe

Flavescence dorée (FD) is a European quarantine grapevine disease transmitted by the Deltocephalinae leafhopper Scaphoideus titanus. Whereas this vector had been introduced from North America, the possible European origin of FD phytoplasma needed to be challenged and correlated with ecological and genetic drivers of FD emergence. For that purpose, a survey of genetic diversity of these phytoplasmas in grapevines, S. titanus, black alders, alder leafhoppers and clematis were conducted in five European countries. Out of 132 map genotypes, only 11 were associated to FD outbreaks, three were detected in clematis, whereas 127 were detected in alder trees, alder leafhoppers or in grapevines out of FD outbreaks. Most of the alder trees were found infected, including 8% with FD genotypes M6, M38 and M50, also present in alders neighboring FD-free vineyards and vineyard-free areas. The Macropsinae Oncopsis alni could transmit genotypes unable to achieve transmission by S. titanus, while the Deltocephalinae Allygus spp. and Orientus ishidae transmitted M38 and M50 that proved to be compatible with S. titanus. Variability of vmpA and vmpB adhesin-like genes clearly discriminated 3 genetic clusters. Cluster Vmp-I grouped genotypes only transmitted by O. alni, while clusters Vmp-II and -III grouped genotypes transmitted by Deltocephalinae leafhoppers. Interestingly, adhesin repeated domains evolved independently in cluster Vmp-I, whereas in clusters Vmp-II and-III showed recent duplications. Latex beads coated with various ratio of VmpA of clusters II and I, showed that cluster II VmpA promoted enhanced adhesion to the Deltocephalinae Euscelidius variegatus epithelial cells and were better retained in both E. variegatus and S. titanus midguts. Our data demonstrate that most FD phytoplasmas are endemic to European alders. Their emergence as grapevine epidemic pathogens appeared restricted to some genetic variants pre-existing in alders, whose compatibility to S. titanus correlates with different vmp gene sequences and VmpA binding properties

Sequential Monte-Carlo Based Framework for Dynamic Data-Driven Event Reconstruction for Atmospheric Release

Atmospheric releases of hazardous materials are highly effective means to impact large populations. We propose an atmospheric event reconstruction framework that couples observed data and predictive computer-intensive dispersion models via Bayesian methodology. Due to the complexity of the model framework, a sampling-based approach is taken for posterior inference that combines Markov chain Monte Carlo (MCMC) and sequential Monte Carlo (SMC) strategies

Microsatellite and Mitochondrial Data Provide Evidence for a Single Major Introduction for the Neartic Leafhopper Scaphoideus titanus in Europe

Scaphoideus titanus, a leafhopper native to North America and invasive in Europe, is the vector of the Flavescence dorée phytoplasma, the causal agent of the most important form of grapevine yellows in European vineyards. We studied 10 polymorphic microsatellite loci and a 623 bp fragment of the mitochondrial cytochrome oxidase II gene in native S. titanus from north-eastern America and introduced European populations, to elucidate the colonization scenario. Consistent with their recent history, invasive European populations were less genetically diverse than American populations for both types of markers, suggesting a recent bottleneck. Significant isolation by distance was detected between American populations but not between European populations. None of the European mitochondrial haplotypes was found in the American vineyards, from which they are assumed to have originated. The precise source of the invasive S. titanus populations therefore remains unclear. Nevertheless, the high heterozygosity of North-East American populations (which contained 92% of the observed alleles) suggests that this region is part of the native range of S. titanus. Clustering population genetics analyses with microsatellite and mitochondrial data suggested that European populations originated from a single introduction event. Most of the introduced populations clustered with populations from Long Island, the Atlantic Coast winegrowing region in which Vitis aestivalis occurs

Effects of different inert dusts on Sitophilus oryzae and Plodia interpunctella during contact exposure: Poster

The use of natural inert dusts against storage insect pests is increasing recently, as an alternative to conventional insecticides. Laboratory study was carried out to evaluate the contact effect of three inert dusts, diatomaceous earth (DE), kaoline (KA) and vermiculite (VE), at rates 5, 7.5, 10, 15 and 20 gm-2, against adults of Sitophilus oryzae (L.) and larvae of Plodia interpunctella (Hubner). Insect mortality was evaluated 1, 2, 3 and 7 days after the exposure. Insect mortality varied depending on the species, concentrations and exposure periods. The DE and KA caused 86.7-98% mortality of S. oryzae after 2 days of exposure at the highest rates, while at 5 and 7.5 gm-2, 100% mortality was achieved only after 7 days. The highest rates of inert dusts caused 42-50% (DE) and 60-75% (KA) mortality of P. interpunctella larvae only after 7days. The mortality of moths increased gradually with the concentration and 100% was achieved 3 days after the contact with DE and KA (10, 15 and 20 g m-2). However, inert dusts induced faster pupation of P. interpunctella, while adult emergence was reduced and adults had smaller body-sizes, compared to control. The VE caused relatively low mortalities (7-11% of S. oryzae adults and 5-8% of P. interpunctella larvae) at all tested rates during the entire experiment. Our results have shown good insecticidal effect of DE and KA against S. oryzae and P. interpunctella at 10, 15 and 20 gm-2. These products could therefore be used by small-scale farmers to protect stored grains against insect pest infestation.The use of natural inert dusts against storage insect pests is increasing recently, as an alternative to conventional insecticides. Laboratory study was carried out to evaluate the contact effect of three inert dusts, diatomaceous earth (DE), kaoline (KA) and vermiculite (VE), at rates 5, 7.5, 10, 15 and 20 gm-2, against adults of Sitophilus oryzae (L.) and larvae of Plodia interpunctella (Hubner). Insect mortality was evaluated 1, 2, 3 and 7 days after the exposure. Insect mortality varied depending on the species, concentrations and exposure periods. The DE and KA caused 86.7-98% mortality of S. oryzae after 2 days of exposure at the highest rates, while at 5 and 7.5 gm-2, 100% mortality was achieved only after 7 days. The highest rates of inert dusts caused 42-50% (DE) and 60-75% (KA) mortality of P. interpunctella larvae only after 7days. The mortality of moths increased gradually with the concentration and 100% was achieved 3 days after the contact with DE and KA (10, 15 and 20 g m-2). However, inert dusts induced faster pupation of P. interpunctella, while adult emergence was reduced and adults had smaller body-sizes, compared to control. The VE caused relatively low mortalities (7-11% of S. oryzae adults and 5-8% of P. interpunctella larvae) at all tested rates during the entire experiment. Our results have shown good insecticidal effect of DE and KA against S. oryzae and P. interpunctella at 10, 15 and 20 gm-2. These products could therefore be used by small-scale farmers to protect stored grains against insect pest infestation

Ovicidal potential of five different essential oils to control gastrointestinal nematodes of sheep

The development of resistance to commercial anthelmintics, particularly in different species of gastrointestinal nematodes (GINs), requires the search for alternatives. Within that context, the aim of this study was to evaluate the in vitro ovicidal activity of five different essential oils (EOs): Origanum vulgare, Satureja hortensis, Thymus vulgaris, Mentha x piperita and Helichrysum arenarium against sheep GINs. For this purpose, the nematode eggs were collected from naturally infected sheep by GINs in two farms located in southern Italy. The egg hatch test (EHT) was performed at six different concentrations (50, 12.5, 3.125, 0.781, 0.195 and 0.049 mg/mL) for each EO. Gas chromatography-mass spectrometry chemical analyses of tested EOs, as well as coproculture examination of tested faecal samples, were also conducted. The results of EHT showed the greatest ovicidal activity of O. vulgare EO with a maximum effect on egg hatching (100%) for all tested concentrations. A similar effect was also shown by S. hortensis and T. vulgaris EOs with an activity of 99.3-100% and 98.5-100%, respectively. M. piperita EO showed medium, dose-dependent ovicidal activity with an inhibitory effect of 72.5-99.8% on the egg hatchability, while the least effective was H. arenarium EO with an activity of 59.8-69.3%. For the anthelmintic activities of the tested EOs are responsible their ingredients, above all carvacrol, thymol, p-cymene and γ-terpinene. The present study demonstrated the significant anthelmintic potential of the tested EOs and emphasizes the possible importance of medicinal plant products for the control of gastrointestinal parasites in sheep

Anthelmintic Properties of Essential Oils to Control Gastrointestinal Nematodes in Sheep—In Vitro and In Vivo Studies

Herbal products such as essential oils may play a promising role in the treatment of infections caused by gastrointestinal nematodes (GINs). The aim of this study was to evaluate the in vitro potential of 11 essential oils (EOs) and one binary combination of isolated EO compounds, as well as the in vivo anthelmintic efficacy of two EO formulations. Four GIN genera were identified in the coproculture examination: Haemonchus, Trichostrongylus, Teladorsagia and Chabertia. The in vitro egg hatch test (EHT) was performed at six different concentrations (50, 12.5, 3.125, 0.781, 0.195 and 0.049 mg/mL) for each EO, whereas in the in vivo faecal egg count reduction test (FECRT), each EO sample was diluted in sunflower oil and orally administrated at a dose of 100 mg/kg to the different group of animals. In the EHT, the EOs of Origanum vulgare, Foeniculum vulgare, Satureja montana, Satureja hortensis and two types of Thymus vulgaris were the most effective. The dominant compounds of these EOs were carvacrol, thymol, anethol, p-cymene and γ-terpinene, indicating their importance for the anthelmintic activity. In the FECRT, both T. vulgaris EO type 1 and linalool:estragole combination show an anthelmintic potential with a mean effect on FECR of approximately 25%. The results suggest the possible role of tested EOs as anthelmintic agents in sheep farms, although further in vivo tests are needed

When a palearctic plant mollicute meets a nearctic insect vector: genetic and ecological insights into the emergence of the grapevine Flavescence dorée epidemics in Europe

International audienc

New insights into the emergence of the grapevine "flavescence dorée" epidemics in Europe

A survey of genetic diversity of “flavescence dorée” (FD)-related phytoplasmas in grapevines, alders and clematis as well as alder-feeding leafhoppers was conducted in France, Hungary, Germany, Italy and Serbia. Genotyping was based on the housekeeping gene map and on the vmp genes encoding surface variable membrane proteins. Transmission assays of the phytoplasmas were performed with alder and/or grapevine-feeding leafhoppers. The study demonstrated that European alders constitute an original reservoir of FD phytoplasma by hosting a high diversity of FD-related phytoplasma genotypes, also present in non viticultural areas. The alder phytoplasmas grouping in Vmp-I cluster were transmitted by the Macropsinae O. alni, but were not compatible with the FD phytoplasma vector on grapevine the Deltocephalinae Scaphoideus titanus. The alder phytoplasmas in Vmp-II and-III clusters were transmitted by the Deltocephalinae Allygus spp. and Orientus ishidae. Such pre-existing phytoplasmas were compatible with S. titanus transmissibility and can be responsible for the emergence of FD phytoplasma epidemics in grapevine. VmpA proteins of cluster II better adhered to Euscelidius variegatus and S. titanus insect cells and midguts than those of cluster I. Such adhesins might play a key role in the adaptation to new vectors

Parasitismo de Trichogramma pretiosum em ovos da traça-das-crucíferas sob diferentes temperaturas Parasitism of Trichogramma pretiosum on diamondback moth eggs under different temperatures

Estudou-se a capacidade de parasitismo de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), em ovos de Plutella xylostella (L.)(Leptoptera: Plutellidae) nas temperaturas de 18; 20; 22; 25; 28; 30 e 32ºC, avaliando-se número de ovos parasitados diariamente, porcentagem acumulada de parasitismo, número total de ovos parasitados por fêmea e longevidade de fêmeas. O ritmo de parasitismo durante as primeiras 24 horas, oscilou de 1,6 a 16 ovos parasitados por fêmea de T. pretiosum nas temperaturas entre 18 e 32ºC. O parasitismo acumulado de ovos de P. xylostella, nas temperaturas de 18; 20; 22; 25; 28; 30 e 32ºC, atingiu 80%, aos 2; 16; 11; 3; 5; 4 e 7 dias, por T. pretiosum. As maiores taxas de parasitismo ocorreram nas faixas térmicas de 25; 28 e 30ºC. A longevidade média de fêmeas de T. pretiosum nas faixas térmicas compreendidas entre 18 e 32ºC, variaram de 2,3 a 13,3 dias.<br>The parasitism capacity of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) on eggs of Plutella xylostella (L.) (Lepidoptera: Plutellidae) was studied, under temperatures of 18; 20; 22; 25; 28; 30 and 32&deg;C aiming to evaluate the number of days with parasitism, cumulated parasitism, total number of eggs parasitized per female and their longevity. Parasitism during the first 24 hours ranged from 1.6 to 16 eggs of P. xylostella per T. pretiosum female in the range of 18 to 32&deg;C. Cumulated egg parasitism of P. xylostella by T. pretiosum reached 80% after 2; 16; 11; 3; 5; 4 and 7 days at 18; 20; 22; 25; 28; 30 and 32&deg;C. Higher parasitism rates were recorded at 25; 28 and 30&deg;C while longevity of T. pretiosum females varied from 2.3 to 13.3 days under temperatures of 18 to 32&deg;C