Papers by Cristina Alfaro
Metabolomics, 2015
Volatile compounds are together with sugars and organic acids the main determinants of tomato fru... more Volatile compounds are together with sugars and organic acids the main determinants of tomato fruit flavour and are therefore important for consumer acceptance. Consequently, in the last years many studies have been performed using different volatile analytical techniques on a large diversity of tomato fruits, aimed mainly at detecting the compounds affecting flavour or at the identification of QTLs and key genes involved in fruit volatile contents. The comparison of three of the analytical methods most commonly applied (headspace, solid phase microextraction, adsorption on Tenax followed by thermal desorption) revealed not only differences in sensitivity, but also dramatic variations in the volatile profile obtained by each of these techniques. The volatile profile was also largely influenced by the way samples were processed before analysis. Four widely used sample processing methods were compared (whole tomato, sliced fruit and two different types of fruit paste), each one producing a characteristic volatile pattern. Therefore, great care should be taken when comparing results available from the literature obtained by means of different methods, or when using the volatile levels obtained in an experiment to predict their influence on tomato flavor or consumer preference, or to assess the success of breeding programs.
Pest Management Science, 2010
BACKGROUND: The control of California red scale, Aonidiella aurantii (Maskell), has encountered m... more BACKGROUND: The control of California red scale, Aonidiella aurantii (Maskell), has encountered many difficulties, which has raised interest in alternative control methods. Up to now, the A. aurantii sex pheromone has been used only for monitoring. In a previous work the authors described a biodegradable mesoporous pheromone dispenser for mating disruption. To verify the efficacy of these dispensers, three field trials were conducted, and the results are shown in this paper.RESULTS: The study of the release profile of these dispensers revealed a mean pheromone emission value of 269 µg day−1 and levels of residual pheromone of 10% at the end of 250 days. During the second flight, an A. aurantii male catch reduction of 98% was achieved in the mating disruption plot of trial 1, 93.5% in trial 2 and 76.7% in trial 3. During the third flight, reductions were 94.1, 82.9 and 68.1% in trials 1, 2 and 3 respectively. Considering damaged fruit with more than five scales, reductions of about 8...
Pest Management Science, 2010
BACKGROUND: Chemosterilization technique has been demonstrated to reduce the population and fruit... more BACKGROUND: Chemosterilization technique has been demonstrated to reduce the population and fruit damage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) in citrus orchards. Field trials showed efficacy by reducing the fruit fly population, that was progressively achieved by continuous application of lufenuron to several generations. Different authors have suggested that field trials should be carried out in isolated or wide areas in order to reduce fruit fly intrusion and obtain best results. In this way, a wide area trial over 3,600 hectares is under investigation in Valencia (Spain) since 2002 to validate the chemosterilization technique against the fruit fly. The whole area was treated with 24 traps per ha, using more than 86,000 traps in the field trial. RESULTS: A continuous decrease of fruit fly population was observed along the four years under trial. Moreover, results show a significant reduction of persimmon damage in the chemosterilant treatment area compared with malathion aerial treated area. In the case of citrus damage, no significant differences were obtained between malathion and chemosterilant treatments. CONCLUSION: The chemosterilant method reduces Mediterranean fruit fly populations, therefore it is a candidate treatment to replace aerial treatments with insecticides in order to suppress Mediterranean fruit fly populations. In addition, the efficacy of chemosterilant treatment increases year after year. The possibility of using this technique combined with other control methods is discussed.
Pest Management Science, 2011
BACKGROUND: New directives on sustainable use of pesticides have encouraged research on efficient... more BACKGROUND: New directives on sustainable use of pesticides have encouraged research on efficient alternative pest control methods. In the case of the California red scale (CRS), Aonidiella aurantii (Maskell), this imperative, along with the many difficulties in controlling this pest, have led to the investigation of new approaches. Previously developed mating disruption (MD) dispensers, together with the augmentative releases of the parasitoid Aphytis melinus DeBach, are here considered as a combined strategy for use against A. aurantii.RESULTS: Efficacy of MD was demonstrated by a mean reduction of 80% in CRS male catches and a mean fruit damage reduction of 83% compared with the control. A delay in the development of A. aurantii instars was observed in the MD plot. This delay increased the period of exposure of the susceptible instars to natural enemies, which resulted in higher predation and parasitism levels in the MD plot. Under laboratory conditions, A. melinus mating behavio...
Journal of Economic Entomology, 2009
Traditional chemical control against Chilo suppressalis Walker is currently being replaced in Spa... more Traditional chemical control against Chilo suppressalis Walker is currently being replaced in Spain by new methods based on pheromones. A key step to improve the efÞcacy of these methods is the determination of the optimum pheromone release rate, which is still uncertain for this pest. In this work, the pheromone release proÞle and the Þeld performance of a new mesoporous dispenser was compared with a standard commercial dispenser. For this purpose, pheromone loads were extracted from Þeld-aged dispensers and quantiÞed by gas chromatography with ßame ionization detector. In addition, a Þeld trial was carried out with traps baited with one, two, or three mesoporous dispensers per trap, as well as with traps containing one standard dispenser. We found that the highest number of Þeld catches did not correspond to the highest pheromone emission rate, which suggests a repellent effect of the insect if the emission is excessive. The results suggest that the attractant activity was maximized by emitting ϳ34 g/d. The efÞcacy of the mesoporous dispenser and its possible improvements are discussed.
International Journal of Food Science & Technology, 2009
SummaryThe control of the raw material has a great influence on the final quality of wine. Nowada... more SummaryThe control of the raw material has a great influence on the final quality of wine. Nowadays, wineries have practically not incorporated an effective quality control of grape juice on their production process. Although wine aroma has been widely analysed, grape juice aroma for wine‐making has been poorly studied. In this study, two headspace‐based technique methodologies have been proposed to characterise the aroma of grape juice: static headspace (SHS) and headspace solid phase microextraction (HS‐SPME). Both techniques were applied on the samples from three maturation stages of two red grape cultivars: Tempranillo and Bobal, ranked first in Spanish and in Valencian Community cultivars, respectively. This study identifies the principal volatile compounds of grape juice: C6 compounds, especially alcohols and aldehydes, using both techniques. It was confirmed that SHS and HS‐SPME techniques could be incorporated into the process of the grape quality control in wineries as a re...
Entomologia Experimentalis et Applicata, 2011
Since the discovery of Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae) sex pher... more Since the discovery of Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae) sex pheromone, it has played an important role in the control and detection of this pest, for example, through the use of pheromone-baited traps and mating disruption techniques. Rubber septa are the most common pheromone dispensers used in monitoring traps, but often dispenser performance is not optimized. The key to improve methods based on pheromones as attractants (monitoring, mass trapping, or 'attract and kill') is to know the optimum emission interval, because release rates can strongly affect the attraction. In this work, five levels of pheromone load with different release rates were compared in traps using mesoporous pheromone dispensers to investigate the optimum release rate maximizing L. botrana catches. Residual pheromone loads of the dispensers were extracted and quantified by gas chromatography, in order to study release profiles and to estimate the various emission levels. The efficacy of pheromone emission was measured in field trials as number of moths caught. A quadratic model was fitted to relate the numbers caught vs. the daily emission rates. The resulting quadratic term was statistically significant, confirming the existence of a relative maximum for L. botrana catches. Taking into account that the trial was carried out only in one location, an optimum emission value of ca. 400 µg per day could be considered to enhance the attraction of L. botrana under West-Mediterranean weather conditions.
Journal of Agricultural and Food Chemistry, 2011
Considerable efforts have been devoted to understanding the courtship behavior and pheromone comm... more Considerable efforts have been devoted to understanding the courtship behavior and pheromone communication of medflies; however, the sex pheromone composition is still a controversial subject. The discovery of new components affecting medfly behavior would be of interest for medfly control methods based on semiochemicals. This work describes volatile compounds emitted by Ceratitis capitata collected using solid phase microextraction. The volatile study was conducted according to an experimental design with three factors (sex, age, and mating status) assumed to be relevant for better understanding the chemical communication. Emission data were treated by means of principal component analysis, a statistical methodology not previously applied to the study of volatiles emitted by fruit flies. The characterization of emission patterns could be useful for the selection of compounds to be further investigated in biological assays to improve knowledge of the key semiochemicals involved in medfly behavior.
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Papers by Cristina Alfaro