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Guidelines for statistically sound and risk-based surveys of Xylella fastidiosa
Get PDFAt the request of the European Commission, EFSA prepared specific guidelines for the survey of Xylella fastidiosa to guide the survey or through the design of statistically sound and risk-based surveys, integrating the key biological information. Based on examples, three different survey designs are simulated: detection surveys to substantiate pest freedom, delimiting surveys to determine the boundaries of an infested zone, and buffer zone surveys to monitor a zone ensuring pest detection at a low level of prevalence. The first step of the survey design consists of setting out the aims of the survey, characterising the host plant population and the methods used to identify the pest. All the survey parameters are quantified considering the importance of the related assumptions. The more accurate the information used to select/estimate the survey parameters, the more robust the conclusions of the survey will be. The second step of the survey design consists of the sample-size calculation using the survey parameters as inputs forthe statistical tool (RiBESS+). The last step of the survey design is the allocation of the samples in the survey area, the method for which depends on the information available on the target population and risk factors. The robustness of the conclusions of surveys designed using these approaches depends strongly on the survey preparation. The methodology here proposed allows surveys to be compared across time and space, thus contributing to harmonisation of the X. fastidiosa surveys in the EU Member States. The extremely flexible approaches allow surveys to be tailored to each specific situation in the Member States, taking into account the host plants, vectors, climate suitability and resources available. The success of a good survey design relies on technical aspects of the survey preparation and on the involvement of the risk managers
SILVOLIVE, a Germplasm Collection of Wild Subspecies With High Genetic Variability as a Source of Rootstocks and Resistance Genes for Olive Breeding
Get PDFWild subspecies of Olea europaea constitute a source of genetic variability with
huge potential for olive breeding to face global changes in Mediterranean-climate
regions. We intend to identify wild olive genotypes with optimal adaptability to different
environmental conditions to serve as a source of rootstocks and resistance genes for
olive breeding. The SILVOLIVE collection includes 146 wild genotypes representative of
the six O. europaea subspecies and early-generations hybrids. These genotypes came
either from olive germplasm collections or from direct prospection in Spain, continental
Africa and the Macaronesian archipelago. The collection was genotyped with plastid and
nuclear markers, confirming the origin of the genotypes and their high genetic variability.
Morphological and architectural parameters were quantified in 103 genotypes allowing
the identification of three major groups of correlative traits including vigor, branching
habits and the belowground-to-aboveground ratio. The occurrence of strong phenotypic
variability in these traits within the germplasm collection has been shown. Furthermore,
wild olive relatives are of great significance to be used as rootstocks for olive cultivation.
Thus, as a proof of concept, different wild genotypes used as rootstocks were shown
to regulate vigor parameters of the grafted cultivar “Picual” scion, which could improve
the productivity of high-density hedgerow orchards
Long-Term Effects Following Fresh/Vitrified Embryo Transfer Are Transmitted by Paternal Germline in a Large Size Rabbit Cohort
Get PDFThe concept of developmental programming suggests that the early life environment influences offspring phenotype in later life, whose effects may also be manifested in further generations. Valuable pieces of evidence come from the fields applying assisted reproductive technologies (ARTs), which deprive embryos of their optimal maternal environment and were thus associated with subsequent developmental deviations. Recently, we demonstrated that the in vitro manipulations during a vitrified embryo transfer procedure incurs a cumulative and transgenerational decline in the growth performance of the resulting offspring. Here, we provide a longitudinal study to investigate whether previous developmental deviations could be indistinctly paternally or maternally transmitted using crossbred mattings. Our findings revealed that early embryo manipulations through fresh and vitrified embryo transfer incurred paternally transmissible effects over the growth pattern and adult body weight, which seemed not inheritable via the female germline. Similar inheritable effects were observed after fresh and vitrified embryo transfer, suggesting that disturbing optimal embryo development through in vitro manipulations was the principal trigger of transmissible effects, rather than embryo cryopreservation per se
The dynamic of antibiotic resistance in commensal Escherichia coli throughout the growing period in broiler chickens: fast-growing vs. slow-growing breeds
Get PDFAntimicrobial resistance (AMR) is an important threat to public health worldwide. Furthermore, different studies have demonstrated a close association between antibiotic use in animal production and AMR in humans. It is well known that it is necessary to reduce antibiotic administration in farms by finding effective alternative treatments, using more resistant breeds and improving animal welfare. However, to be able to assess the alternatives proposed, it is essential to study the epidemiology of AMR under production conditions. Hence, the aim of this study was to investigate the AMR dynamic in 2 genetic poultry breeds during the growing period. The study was performed in 2 experimental poultry houses to simulate real production conditions, and no antibiotics were administered during the growing period. In addition, 2 poultry breeds were used, fast-growing and slow-growing. To evaluate AMR evolution, Escherichia coli was selected as indicator bacterium. To this end, animals from each experimental group were sampled at different times: on day of arrival, at mid-period, and at slaughter day. In the laboratory, cecal content was removed and inoculated in selective media. Then, biochemical tests were performed to confirm E. coli. Finally, antibiotic susceptibility was assessed according to Decision 2013/653. At the onset of the cycle, significant differences were observed between breeds, as the E. coli strains isolated from fast-growing 1-day-old-chicks showed higher AMR rates. However, at the end of the period, no significant differences were found between breeds and their presence of resistant bacteria (above 95%). Therefore, although no antibiotics were administered during the growing period, a high level of AMR at slaughter day was demonstrated. Further studies are necessary to determine the main risk factors that increase the level of AMR throughout the productive cycle in broiler chickens. In conclusion, it is important to highlight that although it is crucial to control both antibiotic use and animal welfare during the growing period, measures should be taken at all levels of the production chain
‘Candidatus Liberibacter Solanacearum’ Is Unlikely to Be Transmitted Spontaneously from Infected Carrot Plants to Citrus Plants by Trioza Erytreae
Get PDFBacteria belonging to ‘Candidatus Liberibacter spp.’ are associated with various severe diseases in the five continents. The African citrus psyllid Trioza erytreae (Hemiptera: Triozidae) is an efficient vector of citrus huanglongbing-HLB disease, absent in the Mediterranean basin. This psyllid is currently present in the islands and mainland Portugal and Spain, where the prevalence of ‘Ca. Liberibacter solanacearum’ (CaLsol) associated to a carrot disease is high. Trioza erytreae normally feeds on citrus plants but has also been observed on other crops. It would be a great concern to the Mediterranean citrus industry if T. erytreae could transmit this bacterium from carrots to citrus and cause disease; therefore, the transmission of CaLsol from carrot plants to citrus plants was experimentally assessed. Although CaLsol was initially detected on receptor citrus plants in transmission assays by dodder and budding, the infection was not established. The feeding behavior by electrical penetration graphs and oviposition of T. erytreae on carrot plants versus citrus plants was evaluated. Trioza erytreae only reached the phloem in citrus plants. However, it was able to acquire CaLsol from infected carrots but unable to transmit it to citrus plants. CaLsol was detected in some carrot plants immediately after 7 and 14 days (inoculation access period), but it was not detected after one month. Trioza erytreae was unable to complete its life cycle on carrot plants. In conclusion, the efficient vector of bacteria associated to huanglongbing was unable to transmit CaLsol from carrot to citrus plants, but it acquired and transmitted the bacterium from carrot to carrot plants with low efficiency
Statistical model for Plum pox virus prediction in Prunus nursery blocks using vector and virus incidence data in four different European ecological areas
No full textPlum pox virus (PPV) is the causal agent of sharka, the most devastating virus disease of Prunus species. PPV is transmitted by vegetative propagation, particularly by grafting, as well as by aphid species in a nonpersistent manner. The objective of this paper was to evaluate the prevalence and diversity of PPV‐vector aphid species in representative European areas of prunus cultivation. Four experimental nursery plots were established in Skierniewice (Poland), Liria (Spain), Plovdiv (Bulgaria) and Bistrita (Romania). Aphid population was weekly monitored using the sticky shoot method in spring and/or autumn in each nursery plot. Furthermore, we estimated the relative efficiency factor for the main PPV‐vector aphid species using bibliographic and reference data. Aphid diversity in each nursery plot was assessed using the Shannon index and the number of estimated aphid species was calculated by the rarefaction method. The highest diversity of aphid species population was reported in Plovdiv in spring while the lowest diversity was found in Liria in spring. A cluster analysis based on Morisita–Horn similarity index was performed to study the differences in species composition between the four nursery plots and seasons. Aphid population was clearly grouped by location and season. Results showed Aphis spiraecola and Hyalopterus pruni complex were typically spring aphid species, while Anoecia corni and Rhopalosiphum padi dominated autumn catch. Regarding PPV‐vector aphid species present in nursery plots, A. spiraecola was the most prevalent PPV‐vector aphid species in Liria and in Bistrita, showing a high relative efficiency factor of PPV transmission (0.91). Consequently, A. spiraecola should be considered a key actor in the spread of PPV in these regions. Hyalopterus pruni complex was the most prevalent PPV‐vector aphid species in Skierniewice and Plovdiv, showing a very low relative efficiency factor of PPV transmission (0.09). Therefore, the role of H. pruni complex in spread of PPV in these regions can be considered negligible. Furthermore, we statistically demonstrated that the presence of specific PPV‐vector aphid species is associated with the spread of the disease, whereas the biodiversity of aphid species population does not affect the spread of PPV. Finally, the advantages of the use of vector pressure index in the management of sharka disease are discusse
Dose Expression for Pesticide Application in Citrus: Influence of Canopy Size and Sprayer
Get PDFPesticides in three-dimensional (3D) crops are usually applied sidewise, so the vertical component must be considered for adjusting the applications. For this, different approaches have been proposed. Leaf Wall Area (LWA) was selected to express the minimum dose to be used in efficacy field trials for plant protection product (PPP) authorization in northern areas of Europe, where 3D crops are grown as narrow wall-forming structures. However, southern European areas also managed 3D crops as wide walls or globular crops with non-negligible canopy width. Therefore, a Tree Row Volume (TRV) model is thought to be more appropriate for dose expression. Furthermore, efficacy evaluations for pesticide authorization are usually carried out with manual sprayers in young plantations with medium-sized trees. However, growers normally apply PPP with air-blast sprayers in plantations of different tree sizes. The objective of this study was to determine which dose expression is more suitable in citrus orchards, as well as to analyze, in turn, the influence of the sprayer. The results demonstrated that TRV was the most appropriate for dose expression. Knapsacks and air-blast sprayers distributed the spray on the canopy in different ways, and the size of the vegetation influenced the differences between them. Moreover, knapsack sprayers produced higher ground losses, and air-blast sprayers produced higher potential drift
Harvest Time and Postharvest Behavior of Six Japanese Nonastringent Persimmon Cultivars Grown under Mediterranean Conditions
Get PDFPersimmon cultivation has significantly grown in the Mediterranean Region in
recent years. The production concentrates mainly in three astringent cultivars: Kaki
Tipo in Italy, Triumph in Israel, and Rojo Brillante in Spain. Therefore, the varietal
range expansion is one of the current challenges for persimmon producers in this area.
Moreover, the introduction of nonastringent persimmon cultivars is particularly interesting
because they can be commercialized immediately after harvest without applying
deastringency treatment before commercialization. This study evaluated the harvest
period and the postharvest response of six Japanese nonastringent cultivars (Kanshu,
Shinshu, Soshu, Suruga, Youhou, Izu). During two seasons, fruit from each cultivar were
harvested at two maturity stages. Fruit quality (external color, firmness, and total soluble
solids) was evaluated after harvest and after different commercial scenarios (domestic
market: 7 days at 20 8C, market to European Union (EU): 5 days at 5 8C plus 5 days at
20 8C, and market to countries with cold-quarantine treatment requirements: 21 days at
0 8C plus 5 days at 20 8C). Cultivars Kanshu, Shinshu, Soshu, and Izu were identified as
early cultivars, and Soshu was the earliest one, which reached commercial maturity at
the beginning of September. These four cultivars showed good quality after simulating
commercialization on domestic and EU markets. Cultivars Suruga and Youhou overlapped
the current harvest window, but their low chilling injury sensitiveness is
highlighted, so they are of special interest to be cold-stored at the end of the season to
be commercialized in overseas markets
Reprogramming of Citrus Retrotransposons during their Early Speciation
No full textSpeciation of the genus Citrus from a common ancestor has recently been established to begin approximately 8 Mya during the late Miocene, a period of major climatic alterations. In here, we report the changes in activity of Citrus LTR retrotransposons during the process of diversification that gave rise to the current citrus species. To reach this goal, we analyzed four pure species that diverged early during citrus speciation, three recent admixtures derived from those species and an outgroup of the Citrus clade. More than thirty thousand retrotransposons were grouped in 10 linages. Estimations of LTR insertion times revealed that retrotransposon activity followed a species-specific pattern of change that could be ascribed to one of three different models. In some genomes, the expected pattern of gradual transposon accumulation was suddenly arrested during the radiation of the ancestor that gave birth to the current Citrus species. The individualized analyses of retrotransposon lineages showed that in each and every species studied, not all lineages follow the general pattern of the species itself. For instance, inmost of the genomes activity of SIRE elements reached its highest level just before Citrus speciation while Retrofit activity has been steadily growing. Based on these observations we propose that Citrus retrotransposons might respond to those stressful conditions driving speciation as a part of the genetic response involved in adaptation. This proposal implies that the evolving conditions of each species interacts with the internal regulatory mechanisms of the genome controlling the proliferation of mobile elements