ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Native parasitoids associated with Tuta absoluta in the tomato production areas of the Spanish Mediterranean Coast
No full textThe tomato borer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an invasive pest that produces significant damage to tomato crops in the Mediterranean area. Although several species of predatory bugs are successfully being used for biological control of the pest, little is known about the parasitoids that are able to exploit T. absoluta as a host. With the aim of better understanding parasitoid species richness of T. absoluta along the Mediterranean Spanish Coast, we conducted an extensive survey to determine distribution, host plants and habitats where parasitoids are present. Our results indicated that egg parasitoids are naturally scarce but that the species richness of larval/pupal parasitoids is high and includes 20 different species. Seven of these had not been previously reported as T. absoluta parasitoids. The most frequent parasitoid species recovered were Necremnus sp. nr. artynes (Walker), Stenomesius cf. japonicus (Ashmead) and Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae)
Effect of cholesterol-loaded cyclodextrins on the motility of goat sperm frozen in diluents deprived of egg yolk
No full textDiagnostic des viroses et séquençage haut débit : vers un changement de paradigme?
No full textPour être adoptée en routine, une technique de diagnostic de virus doit idéalement présenter les caractéristiques suivantes : techniquement robuste, reproductible et répétable, diagnostic sensible et spécifique, facilité de mise en œuvre, y compris pour des utilisateurs peu formés ou inexpérimentés, automatisable, rapide, économiquement compatible avec les besoins de la filière et basée sur des standards industriels généralisé
Early defoliation in a temperate warm and semi-arid Tempranillo vineyard: vine performance and grape composition
No full textBackground and Aims: Early defoliation (ED) can reduce vine yield and improve fruit composition in vigorous vineyards. The objective of this study was to test the effectiveness of this technique for the Vitis vinifera (L.) cultivar Tempranillo under the temperate warm and semi-arid climatic conditions of south-eastern Spain. Methods and Results: Four treatments were applied over three seasons to drip-irrigated vines, planted with rows orientated north-south and shoots vertically positioned. Non-defoliated vines (control) were compared with vines defoliated either just before anthesis (phenological stage H, treatment ED) or at fruitset [phenological stage J, treatment late defoliation (LD)]. In the fourth treatment, only the leaves facing east were removed at phenological stage H (treatment east ED). In the fourth experimental season, all treatments were managed similarly. Defoliation did not reduce fruitset but reduced berry mass, particularly in the ED and the LD treatments. Defoliation, however, had a cumulative negative effect on vine bud fertility. Even in the fourth experimental season, the yield of the ED treatment was 18% lower than that of the control. Both the ED and particularly the LD treatments increased berry total soluble solids (TSS) and phenolic concentration. The effect of leaf removal on berry TSS and phenolic concentration was not significant in the east ED treatment. Conclusions: Defoliation at fruitset was the most effective treatment for increasing berry phenolics and TSS while maintaining must acidity. Growers should take into account, however, the important yield penalty because of defoliation, particularly in the mid-term. Significance of the Study: Early defoliation of Tempranillo grapes growing in semi-arid and temperate climates needs to be applied with caution and probably limited to specific seasons while consecutive defoliations should be avoided
Terpene Down-Regulation Triggers Defense Responses in Transgenic Orange Leading to Resistance against Fungal Pathogens
No full textTerpenoid volatiles are isoprene compounds that are emitted by plants to communicate with the environment. In addition to their function in repelling herbivores and attracting carnivorous predators in green tissues, the presumed primary function of terpenoid volatiles released from mature fruits is the attraction of seed-dispersing animals. Mature oranges (Citrus sinensis) primarily accumulate terpenes in peel oil glands, with D-limonene accounting for approximately 97% of the total volatile terpenes. In a previous report, we showed that down-regulation of a D-limonene synthase gene alters monoterpene levels in orange antisense (AS) fruits, leading to resistance against Penicillium digitatum infection. A global gene expression analysis of AS versus empty vector (EV) transgenic fruits revealed that the down-regulation of D-limonene up-regulated genes involved in the innate immune response. Basal levels of jasmonic acid were substantially higher in the EV compared with AS oranges. Upon fungal challenge, salicylic acid levels were triggered in EV samples, while jasmonic acid metabolism and signaling were drastically increased in AS orange peels. In nature, D-limonene levels increase in orange fruit once the seeds are fully viable. The inverse correlation between the increase in D-limonene content and the decrease in the defense response suggests that D-limonene promotes infection by microorganisms that are likely involved in facilitating access to the pulp for seed-dispersing frugivores
Are there differences on spray deposit distribution pro-duced on citrus canopies by conventional and low-drift nozzles?
Get PDFAir injection nozzles are often recommended to reduce drift, which is one of the major pollu-tion sources caused by the application of plant protection products on fruit trees. However, it is important to know if the use of low-drift nozzles may affect the efficacy of treatments. This work is aimed at providing scientific evidence to asses if there are changes in the deposition pattern on citrus canopies when using conventional (cone) and low-drift (air injection) nozzles and discuss the consequences on efficacy of pesticides. Results showed that the air injection nozzles did not affect deposition in the conditions of the experiments, so they suggest that these nozzles can be regarded as a good alternative to the conventional ones
Assessment of flower number per inflorescence in grapevine by image analysis under field conditions
No full textBACKGROUND
Flowers, flowering and fruit set are key determinants of grapevine yield. Currently, practical methods to assess the flower number per inflorescence, necessary for fruit set estimation, are time and labour demanding. This work aims at developing a simple, cheap, fast, accurate and robust machine vision methodology to be applied to RGB images taken under field conditions, to estimate the number of flowers per inflorescence automatically.
RESULTS
Ninety images of individual inflorescences of Vitis vinifera L. cultivars Tempranillo, Graciano and Carignan were acquired in the vineyard with a pocket RGB camera prior to flowering, and used to develop and test the ‘flower counting’ algorithm. Strong and significant relationships, with R2 above 80% for the three cultivars were observed between actual and automated estimation of inflorescence flower numbers, with a precision exceeding 90% for all cultivars.
CONCLUSION
The developed algorithm proved that the analysis of digital images captured by pocket cameras under uncontrolled outdoors conditions was able to automatically provide a useful estimation of the number of flowers per inflorescence of grapevines at early stages of flowering
The effects of foliar fertilization with iron sulfate in chlorotic leaves are limited to the treated area. A study with peach trees (Prunus persica L. Batsch) grown in the field and sugar beet (Beta vulgaris L.) grown in hydroponics
Get PDFCrop Fe deficiency is a worldwide problem. The aim of this study was to assess the effects of foliar Fe applications in two species grown in different environments: peach (Prunus persica L. Batsch) trees grown in the field and sugar beet (Beta vulgaris L. cv. “Orbis”) grown in hydroponics. The distal half of Fe-deficient, chlorotic leaves was treated with Fe sulfate by dipping and using a brush in peach trees and sugar beet plants, respectively. The re-greening of the distal (Fe-treated) and basal (untreated) leaf areas was monitored, and the nutrient and photosynthetic pigment composition of the two areas
were also determined. Leaves were also studied using chlorophyll fluorescence imaging, low temperature-scanning electron microscopy microanalysis, scanning transmission ion
microscopy-particle induced X-ray emission and Perls Fe staining. The distal, Fe-treated leaf parts of both species showed a significant increase in Fe concentrations (across the whole leaf volume) and marked re-greening, with significant increases in the
concentrations of all photosynthetic pigments, as well as decreases in de-epoxidation of xanthophyll cycle carotenoids and increases in photochemical efficiency. In the basal, untreated leaf parts, Fe concentrations increased slightly, but little regreening occurred. No changes in the concentrations of other nutrients were found. Foliar Fe fertilization
was effective in re-greening treated leaf areas both in peach trees and sugar beet plants. Results indicate that the effects of foliar Fe-sulfate fertilization in Fe-deficient, chlorotic leaves were minor outside the leaf surface treated, indicating that Fe mobility within the
leaf is a major constraint for full fertilizer effectiveness in crops where Fe-deficiency is
established and leaf chlorosis occurs
Postteneral Protein Feeding may Improve Biological Control Efficiency of Aphytis lingnanensis and Aphytis melinus
Get PDFThe augmentative releases of mass-reared Aphytis spp. (Hymenoptera: Aphelinidae) parasitoids are widely used against armored scales. The nutritional status and the initial egg load of Aphytis spp. females are key to their success as biological control agents. For these reasons, this work focuses on the study of providing a protein feed to Aphytis lingnanensis (Compere) and A. melinus DeBach to improve the egg load before their release. The addition of protein to a honey diet during the first 2 d after the adult parasitoid emergence increased the initial egg load in both species of parasitoids by more than five eggs. Furthermore, the addition of protein increased the total number of eggs laid by A. lingnanensis on oleander scale, Aspidiotus nerii Bouche (Hemiptera: Diaspididae). In contrast, this effect was not observed on A. melinus probably because A. nerii is considered a suboptimal host for this parasitoid. The host-feeding activities of the two Aphytis species were differentially affected by the addition of protein to their diets. These results may have direct implications for augmentative biological control programs, especially during transportation from insectaries to the field, a period of time when parasitoids are deprived of hosts