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Do hyperparasitoids disrupt the biological control of Pseudococcus longispinus in persimmon?
No full textThe long-tailed mealybug, Pseudococcus longispinus, represents a threat for several crops worldwide and has become the main pest of Mediterranean persimmon. Parasitoids are the primary natural enemies of P. longispinus, but their efficacy is highly variable among crops and countries. Here, we tested whether hyperparasitoids hinder the biological control of P. longispinus in Mediterranean persimmon. For this aim, we sampled 16 orchards across two consecutive years and measured the impact of primary parasitoids and hyperparasitoids on P. longispinus. Anagyrus fusciventris was the most abundant and widely distributed primary parasitoid. Population growth rate of the mealybug became negative when parasitism was higher than 30%. The hyperparasitoids Chartocerus sp. and Prochiloneurus sp. emerged mostly from large mealybug mummies that were used by A. fusciventris females. However, and contrary to our hypothesis, hyperparasitism did not affect the population growth rate of P. longispinus within the same year, suggesting that the high abundance of hyperparasitoids did not disrupt the biological control of this invasive mealybug. Based on these results, we propose several strategies based on conservation and augmentative biological control to improve the management of P. longispinus in persimmon
Influencia del diseño agronómico en la acumulación de boro en árboles de limonero temprano "Fino 49"
Get PDFLa Región de Murcia es la principal productora de limón de España. Sin embargo, la climatología en esta región es semiárida, y bajo estas condiciones, la viabilidad de las explotaciones agrícolas depende principalmente de la disponibilidad y manejo agronómico de los recursos hídricos. En la actualidad, los agricultores complementan parte de los recursos hídricos convencionales disponibles con otros recursos no convencionales, como el agua de mar desalada o las aguas depuradas. Sin embargo, estos recursos no convencionales pueden presentar elevadas concentraciones de cloro, sodio y especialmente boro (B), que puede reducir la productividad de cultivos especialmente sensibles, como los cítricos, que presentan bajos umbrales de fitotoxicidad por boro (0,5 mg L-1 en el agua de riego). Respecto al manejo agronómico, mejoras en el diseño agronómico de la instalación de riego buscando un incremento de la superficie mojada pueden, por un lado, ayudar a aumentar la capacidad hidráulica de la planta, lo que podría favorecer la productividad del cultivo, pero también favorecen la acumulación en hoja de diferentes elementos minerales. Por lo tanto, el objetivo del experimento fue evaluar si un aumento en el volumen mojado del suelo al incrementar el número de goteros por árbol puede favorecer la acumulación de boro en hoja y cómo responde agronómicamente el cultivo. El ensayo se llevó a cabo durante tres campañas (2017-2019) en una parcela experimental en Torre Pacheco (Murcia), en árboles adultos de limonero ‘Fino 49’ injertados sobre Citrus macrophylla. Se han evaluado dos diseños del sistema de riego: diseño convencional (2L), con dos tuberías portagoteros (6 goteros árbol-1); y un diseño con mayor superficie mojada (3L), con tres tuberías (9 goteros árbol-1), aplicando la misma cantidad de agua de riego en ambos tratamientos. Se realizó un seguimiento periódico de la calidad del agua de riego recibida en el embalse de la parcela (pH, CE, Na, Cl, Ca, Mg, y principalmente B). En noviembre de cada campaña se realizó un muestro foliar en 12 árboles por tratamiento para el análisis de contenido mineral en hoja de macronutrientes y micronutrientes (principalmente B). En los mismos árboles, se realizó la cosecha, determinando el número de frutos cosechados y los kilogramos obtenidos por árbol. Los principales resultados indicaron que los
valores promedio de B en el agua de riego durante el periodo experimental estuvieron muy cercanos a los 0,50 mg L-1. Esto se vio reflejado en los niveles de B en hoja, que se incrementaron anualmente, hasta alcanzar en la última campaña valores de 197 ppm y 179 ppm en el tratamiento 2L y 3L respectivamente, más del doble de los registrados en 2017. Dicho aumento del contenido de B en hoja estuvo relacionado significativamente con una reducción de la producción, en un 44% y 41%, debido a una disminución del número de frutos cosechados del 50% y 47% en el tratamiento 2L y 3L respectivamente, respecto a la primera campaña. Por lo tanto, los diferentes diseños agronómicos estudiados respondieron de manera similar a la acumulación de boro en hoja con similares efectos sobre la producción
Recubrimientos comestibles funcionales en combinación con atmósfera modificada pasiva para extender la vida útil y mejorar la calidad de pera "conferencia" mínimamente procesada
No full textEarly detection of Penicillium Digitatum using hyperspectral imaging and deep learning
Get PDFFungal infections are a main concern in fruit packing houses since one infected orange
can cause a whole storage room to be infected in case the infection is not detected. For
that reason, early detection before the infection is visible by the human eye is crucial. In
many packing houses, UV light is used to manually sort oranges, but it can be dangerous
for the eyes. Besides, at the very beginning of the infection, it can be difficult to detect it
even using UV light, and since the human eye gets exhausted when working for hours,
that makes human early detection not suitable for the task. However, hyperspectral imaging
can solve that problem since it avoids the use of UV light and humans due to its
ability to detect not only external but also internal information of the fruit.
For that reason, a preliminary study was carried on using 100 oranges of Navel-late
variety. 50 of them were inoculated with distilled water as a control, and 50 of them with
Penicillium Digitatum with a concentration of 106 spores ml-1. After that, they were
stored at 20ºC and 90% relative humidity for 4 days. Images were taken at the day of
inoculation and every day for 4 days after inoculation, taking a total of 500 images.
Hyperspectral images of these fruits were acquired with a VIS/NIR pushbroom hyperspectral
imaging system (900-1700 nm) and were corrected with the white and dark
reference and the background was removed. Images were then divided into train (60%
of the images), validation (20% of images) and test (20% of images) datasets of healthy
and inoculated images.
Unlike most authors who use 2D CNNs, we have used a 3D customized CNN which is
designed for 3-dimension data, and which allows obtaining more spectral information
than 2D CNNs. Images were resized to 100 x 100 pixels due to computational limitations
and data augmentation was applied before training to increase the number of samples.
Results showed that after one day, the model was able to classify correctly 100% of the
control oranges and 80% of the inoculated ones, proving that this technology might be
able to predict infection after it is visible by the human eye and even when using UV light.
However, this should and will be studied in a future using more samples and better computational
resources as to improve the model and the image resolution
Physico-chemical and microstructural changes during the drying of persimmons with different disorders. Consumer acceptance of dried slices as a criterion to valorise discards
Get PDFIn this study, consumer acceptance of the final product is used as a criterion to evaluate the viability of valorising persimmons by obtaining dried slices from fruit that manifest different disorders: skin damage and malformations detected at harvest, and flesh browning and chilling injury manifested in astringent and non-astringent fruit during the postharvest period. During drying, slices shrunk and underwent colour changes linked with browning. In microstructural terms, the drying process was associated mainly with cell wall degradation in parenchyma tissue and cell shrinkage. Such changes were less marked in the dried slices obtained from the astringent fruit affected by chilling injury, which was linked with a higher soluble tannins content at the beginning of the dehydration process and resulted in more appealing slices. These slices completely lost their astringency during drying. The sensory study performed with 96 consumers showed that the obtaining dried persimmon slices is a promising way to valorise fruit discarded at harvest due to in-field damage and those discarded after storage due to chilling injury symptoms. Consumers liked these samples and reported 60% and 70% purchase intention, respectively. It is necessary to investigate other alternatives to valorise discards from fruit affected by flesh browning
Quantifying the ultraviolet-induced fluorescence intensity in green mould lesions of diverse citrus varieties: Towards automated detection of citrus decay in postharvest
No full textCitrus fungal infections developing during fruit storage and transportation can cause significant economic losses after harvest. The most important is caused by the fungus Penicillium digitatum, which infects the fruit through rind wounds and causes a rot lesion. The symptoms of decay are difficult to notice by the human eye in the initial stages of decay development because the colour of the lesion is very similar to that of the healthy rind. One method to detect this disease early is to illuminate the fruit with ultraviolet (UV) light since the disease causes visible fluorescence. Manual inspection exposes the workers to UV light, which is dangerous for their skin and eyes. An alternative is to use artificial vision systems. But not all varieties show the same level of fluorescence, and even some do not produce this phenomenon, making it challenging to create effective automatic detection systems based on image analysis. This work has studied and determined the fluorescence level of 104 varieties of oranges and mandarins using hyperspectral and colour imaging. The samples were inoculated with spores of the P. digitatum in controlled conditions. Images were captured exposing the fruit under UV light (380 nm) using a colour camera and a hyperspectral imaging system. The fluorescence level of each variety was measured using three colour coordinates and the hyperspectral images. Best correlations between the spectral and the colour-based systems were achieved using the green (G) colour coordinate of the RGB colour space (R2 =0.85). Navel and common oranges emit the most fluorescence, while 16 varieties (mostly blood oranges and other mandarins) have very low or undetectable fluorescence
Estudio preliminar de la modulación circadiana en el comportamiento alimentario en porcino
Get PDFEl desarrollo de alimentadores automáticos ha permitido medir caracteres de comportamiento de alimentación,
como el número de visitas, la duración, y el consumo, entre otros. Un mayor conocimiento
de ellos podría ayudar a aclarar su función ejercida sobre el consumo, la tasa de crecimiento y las rela -
ciones sociales entre animales. Los caracteres de comportamiento alimentario podrían estar influenciados
por factores relacionados con el propio individuo, el ambiente, o a la interacción entre ambos.
El objetivo de este trabajo es estudiar la modulación circadiana en caracteres de comportamiento alimentario
como el número de visitas, duración de las visitas, y consumo por visita evaluados en meses
cálidos y frescos
¿Puede el injerto en pimiento inducir tolerancia a bajas temperaturas en la variedad?
Get PDFEl estrés por bajas temperaturas se agrava con el cambio climático, dado que hay más
eventos de temperaturas extremas. Las bajas temperaturas inciden sobre los cultivos
afectando negativamente al aparato fotosintético, se acumulan especies reactivas de
oxígeno, dificultan la función de los órganos reproductivos femeninos y reducen la
cantidad de polen viable, disminuyendo el rendimiento y la calidad del fruto. El injerto
constituye una tecnología eficiente para inducir tolerancia a estreses abióticos,
incluyendo estrés térmico, aunque no se dispone de patrones de pimiento tolerantes a
bajas temperaturas. En este trabajo se testaron accesiones de Capsicum (C. annuum L., C.
chinense Jacq. y C. frutescens L.) como patrones para injertar la variedad Maestral (C.
annuum) en estrés por frío (12ºC/6ºC). La biomasa de la parte aérea (DW/FW), la
conductancia estomática (gs) y la tasa relativa de crecimiento (RGR) fueron parámetros
discriminantes para caracterizar la tolerancia o susceptibilidad de las accesiones y
seleccionar combinaciones patrón-variedad en las que estudiar mecanismos fisiológicos
implicados en la tolerancia. Se observaron diferentes grados de tolerancia y sensibilidad al
estrés, el patrón 13 fue altamente sensible con menor RGR, gs y DW/FW, elevado estrés
oxidativo (actividad SOD, CAT, APX, contenido de H2O2 y AsA). El patrón 16 mostró mayor
RGR, gs y DW/FW y menor presión oxidativa entre todos los genotipos, siendo un patrón
candidato para futuros estudios de tolerancia. Los demás patrones mostraron grados
intermedios de tolerancia y sensibilidad al estrés. Este trabajo explora las estrategias de
respuesta al estrés por frío y proporciona marcadores para seleccionar genotipos
tolerantes que puedan emplearse como patrones de pimiento en condiciones de estrés
por baja temperatura
Agroecology-inspired strategies and tools to enhace resilience and ecosystem services in tomato crop (ASTER)
Get PDFTomato is a key crop worldwide, particularly in the Mediterranean Basin. Its market
value in the EU represents about 7 billion euros. Tomato can be grown in open fields or
protected conditions, and short or long production periods can be possible due to the large
availability of commercial varieties. Regardless of the type of cultivation or the duration of the
cycle, increasing quantities of external inputs (pesticides, fertilisers, herbicides) are required to
cope with i) nutrition issues linked to the deployment of the soil, ii) resident and invasive
species made more aggressive by the climatic change and the development of pesticide
resistance; iii) water limitation which is more critical in arid and semi-arid climates of the
Mediterranean area due to climatic change. The PRIMA project “ASTER” aims to build up a
management model for small tomato producers of the Mediterranean Basin based on the
application of main agroecology principles such as (i) the conservation and the enhancement of
functional biodiversity both above and belowground, to increase and exploit the ecosystem
services (protection, nutrition, pollination) in alternative to the use of external synthetic inputs;
(ii) the sustainable control of main pests and pathogens to reduce the environmental impact of
plant protection practices; (iii) the circularity of the production chain to approach the “zero
waste” objective. ASTER will improve the tomato resilience in the economy of all
Mediterranean Basin countries where it can be grown in open fields or protected systems,
during the entire annual season, particularly in small farms
Garlic and peppermint essential oils induce defensive responses on sweet peppers
Get PDFPlant essential oils (EOs) are a promising tool for the sustainable control of
agricultural pests, however, their impact on plants and the associated trophic networks has been
scarcely investigated. We studied in the laboratory whether different nanoformulated EOs can
induce defences on sweet pepper, Capsicum annuum, by foliar application. Firstly, through a
dual choice test, based on the olfactory response of the model parasitoid Encarsia formosa,
garlic and peppermint EOs were selected among different plant extracts over four botanical
families (i. e., Apiaceae, Asteraceae, Liliaceae and Lamiaceae). The behavioural responses of
the herbivores Bemisia tabaci, Frankliniella occidentalis and the predators Orius laevigatus
and Nesidiocoris tenuis to EO induced plant volatiles were thus investigated. The expression
level of defence-related genes in plant tissues and the phytotoxic impact in the whole plant were
measured in response to EO foliar applications in sweet pepper. Garlic and peppermint EOsprayed
plants at different concentrations triggered different behavioural responses on both
pests and natural enemies in olfactory trials. Gene expression analysis highlighted activated
defence signalling pathways in EO sprayed sweet pepper plants, while a variable phytotoxic
effect was recorded. Our results suggest that EOs may have an impact on sweet pepper and the
associated trophic network. These findings could serve as a basis for future development of
plant protection strategies in the framework of Integrated Pest Management