ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Parasitic fitness of a strain of Diachasmimorpha longicaudata (Hymenoptera, Braconidae) reared on irradiated larvae of a Vienna-8 strain of Ceratitis capitata (Diptera, Tephritidae)
No full textIntroduction: Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a cosmopolitan pest that has invaded almost all temperate and tropical countries. Biological control of C. capitata is now well established in many American countries, but it is still limited in Europe. Recently, the use of the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera, Braconidae) by field releases in the Valencian Community (Eastern Spain) is being considered as a complement in the management of the pest by the Sterile Insect Technique (SIT). A semi-mass rearing of the parasitoid using irradiated larvae of a medfly Vienna-8 strain was started by the company Tragsa. The aim of this work is to assess the parasitic fitness of the parasitoid colony after several generations of semi-mass rearing. Materials and methods: The bioassay was performed analyzing different fitness-related parameters of the parasitoids: fecundity, percentage of parasitism and superparasitism, and the presence of ovipositors’ scars on medfly pupae. Two parasitoid colonies were compared: a laboratory colony (IVIA) reared on wild-type larvae (larvae from a rearing initiated and periodically refreshed with field individuals) for more than 50 generations and the semi-mass reared colony (Tragsa). Moreover, the two types of host larvae were analyzed as they could potentially affect adult parasitic fitness. Results and discussion: Results show that adults from the Tragsa colony have not lost parasitic fitness after 14 generations reared on irradiated Vienna-8 larvae. Medfly larvae show less suitability to be parasitized for both parasitoid colonies. Conclusion: We can conclude that the mass reared parasitoids are suitable to be released in the field for the biological control of the medfly
Effects of dispersal barriers in the demarcated area in Alicante, Spain, for Xylella fastidiosa. A non-stationary modelling approach
Get PDFSpatial models for plant diseases often assume isotropy and stationarity, implying that the spatial dependence is direction invariant and uniform through the study area. However, these assumptions are violated when dispersal barriers are present in the form of geographical features or disease control interventions. The main objective here was to evaluate the influence of different types of barriers in the distribution of Xylella fastidiosa (Xf) in the demarcated area in Alicante, Spain
Índice de motilidad espermática: evaluación de su utilidad como predictor de la fertilidad de dosis de semen refrigerado de caprino
Get PDFUno de los parámetros más utilizados para valorar muestras seminales es la motilidad, por su facilidad de evaluación. Generalmente, se acepta su importancia sobre la fertilidad de las muestras, ya que los espermatozoides deben ser móviles para progresar en el tracto reproductivo femenino y atravesar las estructuras de los ovocitos (Graham y Mocé, 2005). Los sistemas CASA proporcionan información objetiva acerca de la movilidad permitiendo cuantificar y evaluar la calidad de ese movimiento (Yániz et al., 2018). No obstante, los estudios acerca de la relación entre la movilidad y la fertilidad de las dosis han sido contradictorios (Graham y Mocé, 2005). Recientemente, se ha propuesto un índice de motilidad espermática (SMI) con capacidad pronóstica de la fertilidad en vacuno (Nagata et al., 2018). El objetivo de este trabajo es determinar si el SMI tiene relación con la fertilidad a parto de las dosis refrigeradas de caprino de raza Murciano-Granadina
Parasitic wasps avoid ant-protected hemipteran hosts via detection of ant cuticular hydrocarbons
Get PDFOne of the most studied and best-known mutualistic relationships between
insects is that between ants and phloem-feeding insects. Ants feed on
honeydew excreted by phloem-feeding insects and, in exchange, attack the
phloem feeders’ natural enemies, including parasitic wasps. However, parasitic
wasps are under selection to exploit information on hazards and avoid
them. Here, we tested whether parasitic wasps detect the previous presence
of ants attending colonies of phloem feeders. Behavioural assays demonstrate
thatwasps left colonies previously attended by ants more frequently than control
colonies. This behaviour has a potential cost for the parasitic wasp as
females inserted their ovipositor in fewer hosts per colony. In a further bioassay,
wasps spent less time on papers impregnated with extracts of the ant cues
than on control papers. Gas chromatography coupled withmass spectrometry
analyses demonstrated that ants left a blend of cuticular hydrocarbons when
they attended colonies of phloem feeders. These cuticular hydrocarbons are
deposited passively when ants search for food. Overall, these results suggest,
for the first time, that parasitic wasps of honeydew producers detect the
previous presence of mutualistic ants through contact infochemicals. We
anticipate such interactions to be widespread and to have implications in
numerous ecosystems, as phloem feeders are usually tended by ants
Application of a new wax containing ethanol as a method to remove persimmon astringency during cold storage
Get PDFNowadays the treatment based on applying high CO2 concentrations to fruit is the main method used in astringent persimmon prior to being commercialized, but it can cause quality problems for fruit during cold storage. The aim of this study was to evaluate the effectiveness of a recently patented astringency removal method based on applying a new wax whose formulation includes ethanol before commercial packaging. During two seasons, three treatments were evaluated in cv. Rojo Brillante and Triumph: (1) CO2- standard treatment; (2) waxed and packed in plastic film according to the patented method; (3) packed in plastic film without any treatment. During a third season, the new method’s effectiveness in removing astringency was evaluated under industrial conditions. After treatments fruit was stored at 0 °C for 15, 21 and 30 days before being transferred at 20 °C to simulate a 5-days shelf-life. All the fruit treated with the new wax completely lost astringency after 30 days at 0 °C, and commercial firmness was maintained. At the end of the storage, fruit quality was substantially higher in fruit submitted to the new treatment. CO2-treated fruit, manifested internal browning after 30 storage days and shelf-life, while this disorder was not detected in waxed fruit
Consumer perception of situational appropriateness for fresh, dehydrated and fresh-cut fruits
Get PDFIn recent years, a decreasing trend in fruit consumption has been detected in Mediterranean countries, with the consequent risk for the population’s health. The objective of this study was to obtain consumer knowledge that can be useful to promote fruit consumption by designing specific interventions. This study was conducted in Spain as its inhabitants have traditionally adhered to the Mediterranean diet. Firstly, four fresh fruit types were identified based on the consumer perception of the fruit characteristics that condition the eating process (fruit size, the need for cutlery to peel/eat fruit, and susceptibility to be spoiled during transportation). Then consumer perception of situational appropriateness of six different fruit types (the 4 types of fresh fruit previously identified, dehydrated non-traditional fruit (DF), and fresh-cut fruit ready to eat on the go (FCF)) was investigated by the Item-By-Use method using Check-All-That Apply (CATA) questions. The potential of DF and FCF to broaden fruit consumption situations, and barriers for their consumption, were evaluated. Fresh fruits, particularly ‘easy-to-peel’ ones like mandarins or bananas, were those preferred by consumers in most evaluated contexts. DF were considered mainly appropriate to be consumed ‘As an ingredient’ and ‘As a healthy snack’, while FCF were more suitable ‘To be included in school lunchboxes’ and ‘To eat immediately’. According to our results, these two processed fruit types can help to increase the fruit consumption of a non-negligible percentage of the population (38% of participants), but it is necessary to overcome the barriers related mostly to sensory properties, plastic packaging and consumer misperception of fewer healthy properties compared to fresh fruit
The P1 Protein of Watermelon mosaic virus Compromises the Activity as RNA Silencing Suppressor of the P25 Protein of Cucurbit yellow stunting disorder virus
Get PDFMixed viral infections in plants involving a potyvirus and other unrelated virus often result in synergistic effects, with significant increases in accumulation of the non-potyvirus partner, as in the case of melon plants infected by the potyvirus Watermelon mosaic virus (WMV) and the crinivirus Cucurbit yellow stunting disorder virus (CYSDV). To further explore the synergistic interaction between these two viruses, the activity of RNA silencing suppressors (RSSs) was addressed in transiently co-expressed combinations of heterologous viral products in Nicotiana benthamiana leaves. While the strong RSS activity of WMV Helper Component Proteinase (HCPro) was unaltered, including no evident additive effects observed when co-expressed with the weaker CYSDV P25, an unexpected negative effect of WMV P1 was found on the RSS activity of P25. Analysis of protein expression during the assays showed that the amount of P25 was not reduced when co-expressed with P1. The detrimental action of P1 on the activity of P25 was dose-dependent, and the subcellular localization of fluorescently labeled variants of P1 and P25 when transiently co-expressed showed coincidences both in nucleus and cytoplasm. Also, immunoprecipitation experiments showed interaction of tagged versions of the two proteins. This novel interaction, not previously described in other combinations of potyviruses and criniviruses, might play a role in modulating the complexities of the response to multiple viral infections in susceptible plants
Automated Detection of Tetranychus urticae Koch in Citrus Leaves Based on Colour and VIS/NIR Hyperspectral Imaging
Get PDFetranychus urticae Koch is an important citrus pest that produces chlorotic spots on the leaves and scars on the fruit of affected trees. It is detected by visual inspection of the leaves. This work studies the potential of colour and hyperspectral imaging (400–1000 nm) under laboratory conditions as a fast and automatic method to detect the damage caused by this pest. The ability of a traditional vision system to differentiate this pest from others, such as Phyllocnistis citrella, and other leaf problems such as those caused by nutritional deficiencies, has been studied and compared with a more advanced hyperspectral system. To analyse the colour images, discriminant analysis has been used to classify the pixels as belonging to either a damaged or healthy leaves. In contrast, the hyperspectral images have been analysed using PLS DA. The rate of detection of the damage caused by T. urticae with colour images reached 92.5%, while leaves that did not present any damage were all correctly identified. Other problems such as damage by P. citrella were also correctly discriminated from T. urticae. Moreover, hyperspectral imaging allowed damage caused by T. urticae to be discriminated from healthy leaves and to distinguish between recent and mature leaves, which indicates whether it is a recent or an older infestation. Furthermore, good results were achieved in the discrimination between damage caused by T. urticae, P. citrella, and nutritional deficiencies
Molecular signatures of silencing suppression degeneracy from a complex RNA virus
Get PDFAs genomic architectures become more complex, they begin to accumulate degenerate and redundant elements. However, analyses of the molecular mechanisms underlying these genetic architecture features remain scarce, especially in compact but sufficiently complex genomes. In the present study, we followed a proteomic approach together with a computational network analysis to reveal molecular signatures of protein function degeneracy from a plant virus (as virus-host protein-protein interactions). We employed affinity purification coupled to mass spectrometry to detect several host factors interacting with two proteins of Citrus tristeza virus (p20 and p25) that are known to function as RNA silencing suppressors, using an experimental system of transient expression in a model plant. The study was expanded by considering two different isolates of the virus, and some key interactions were confirmed by bimolecular fluorescence complementation assays. We found that p20 and p25 target a common set of plant proteins including chloroplastic proteins and translation factors. Moreover, we noted that even specific targets of each viral protein overlap in function. Notably, we identified argonaute proteins (key players in RNA silencing) as reliable targets of p20. Furthermore, we found that these viral proteins preferentially do not target hubs in the host protein interactome, but elements that can transfer information by bridging different parts of the interactome. Overall, our results demonstrate that two distinct proteins encoded in the same viral genome that overlap in function also overlap in their interactions with the cell proteome, thereby highlighting an overlooked connection from a degenerate viral system
Starch-glyceryl monostearate edible coatings formulated with sodium benzoate control postharvest citrus diseases caused by Penicillium digitatum and Penicillium italicum
Get PDFThe curative antifungal activity of edible composite coatings (ECs) based on pregelatinized potato starch-glyceryl monostearate (PPS-GMS) formulated with or without sodium benzoate (SB) to control green mould (caused by Penicillium digitatum) and blue mould (P. italicum) was assessed on ‘Orri’ mandarins, ‘Valencia’ oranges and ‘Fino’ lemons. These fruit were artificially inoculated with P. digitatum or P. italicum, treated by immersion in coating emulsions and compared to uncoated control fruit immersed in water and fruit immersed in 2% SB (w/v) aqueous solution. Treated fruit were then stored at either 20°C or commercial low temperature (5°C for mandarins and oranges, 12°C for lemons). Coatings without SB did not exhibit antifungal activity, whereas coatings containing 2% SB reduced incidence and severity of green and blue moulds, in comparison to the controls, on all citrus species and in all storage conditions, without
differing from the aplication of 2% SB alone. For example, incidence reduction on ‘Fino’ lemons was from 99 to 0% after 7 d at 20°C, and from 99 to 30% after 2 weeks at 12°C. None of the treatments was phytotoxic. These results indicate that applications of SB as antifungal ingredient of PPS-GMS based ECs is a promising non-polluting alternative to control Penicillium postharvest decay of citrus, and these ECs are effective substitutes for conventional waxes amended with synthetic fungicides