Reproductive efficiency of entomopathogenic nematodes as scavengers. Are they able to fight for insect’s cadavers?

Entomopathogenic nematodes (EPNs) and their bacterial partners are well-studied insect pathogens, and their persistence in soils is one of the key parameters for successful use as biological control agents in agroecosystems. Free-living bacteriophagous nematodes (FLBNs) in the genus Oscheius, often found in soils, can interfere in EPN reproduction when exposed to live insect larvae. Both groups of nematodes can act as facultative scavengers as a survival strategy. Our hypothesis was that EPNs will reproduce in insect cadavers under FLBN presence, but their reproductive capacity will be severely limited when competing with other scavengers for the same niche. We explored the outcome of EPN - Oscheius interaction by using freeze-killed larvae of Galleria mellonella. The differential reproduction ability of two EPN species (Steinernema kraussei and Heterorhabditis megidis), single applied or combined with two FLBNs (Oscheius onirici or Oscheius tipulae), was evaluated under two different infective juvenile (IJ) pressure: low (3IJs/host) and high (20IJs/host). EPNs were able to reproduce in insect cadavers even in the presence of potential scavenger competitors, although EPN progeny was lower than that recorded in live larvae. Hence, when a highly susceptible host is available, exploiting cadavers by EPN might limit the adaptive advantage conferred by the bacteria partner, and might result in an important trade-off on long-term persistence. Contrary to our hypothesis, for most of the combinations, there were not evidences of competitive relationship between both groups of nematodes in freeze-killed larvae, probably because their interactions are subject to interference by the microbial growth inside the dead host. Indeed, evidences of possible beneficial effect of FLBN presence were observed in certain EPN-FLBN treatments compared with single EPN exposure, highlighting the species-specific and context dependency of these multitrophic interactions occurring in the soil.Research Subject Categories::FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING::Soil science::Soil biology; Research Subject Categories::NATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Ethology and behavioural ecology; Research Subject Categories::NATURAL SCIENCES::Biology::Terrestrial, freshwater and marine ecology::Terrestrial ecologyinfo:eu-repo/semantics/publishedVersio

Spatial relationships between entomopathogenic nematodes and nematophagous fungi in Florida citrus orchards

Relationships between entomopathogenic nematodes (EPNs), nematophagous fungi (NF) and soil physical and chemical properties were studied in a survey of 53 citrus orchards in central ridge and flatwoods ecoregions of Florida. Seven species of NF associated with nematodes were quantified directly using a real time qPCR assay. All nematophagous fungi studied except Arthrobotrys musiformis and Hirsutella rhossiliensis were frequently detected (24-56%) in both regions. Paecilomyces lilacinus and Gamsylella gephyropagum were encountered more frequently in the flatwoods (P = 0.03) and on the ridge (P = 0.02), respectively. Redundancy analysis revealed seven abiotic and biotic factors as significantly related to the NF occurrence. Multiple regression of fungi on these variables explained 78%, 66%, 48%, 36%, 23% and 4% of the variation in Catenaria sp., A. musiformis, A dactyloides, P. lilacinus, A. oligospora and G. gepharopagum, respectively. When the data from citrus were pooled with those reported previously from natural areas and subjected to principle component analysis, the first two principle components explained 43% of the variation in NF communities. The surveys (citrus vs natural areas) were discriminated by PC2 (P < 0.001) and the ecoregion by PC1 (P < 0.002), and all but one NF species were related (P < 0.01) to one or both components. NF communities tended to have more species and greater diversity in the flatwoods, where EPN richness and diversity were the least. However, the strength of associations between individual EPN and NF species as measured by SADIE reflected the associations between each species and ground water depth, suggesting that ecoregion preferences affected the species associations. Within each ecoregion, significant relationships between the individual NF and EPN species measured by stepwise regression tended to be positive. The results did not support the hypothesis that NF modulate the spatial patterns of EPN species between or within these two ecoregions. (C) 2017 Elsevier Inc. All rights reserved.USDA-CSREES Special Grant (TSTAR)U.S-Egypt Science and Technology Joint Fund [338]Ramon Areces Spanish FoundationMarie Curie International Outgoing Fellowship within the 7th European Community Framework Programme [FP7-PEOPLE-2009-IOF-252980

Entomopathogenic Nematode Compatibility with Vineyard Fungicides

Vineyards, covering over seven million hectares worldwide, holdsignificant socio-cultural importance. Traditionally reliant onconventional practices and agrochemicals, this agroecosystemfaces environmental challenges, including soil and water pollution.Sustainable viticulture, driven by eco-friendly practices and costreduction, has gained prominence, underlining the importance ofbiological control agents such as entomopathogenic nematodes(EPNs). EPNs naturally occurr in vineyard soils and play a crucial rolein controlling pest damage. Ensuring compatibility between EPNsand the commonly used vineyard fungicides is critical, as theseapplications constitute the predominant pest-management practiceduring the productive grapevine cycle.This study assessed the impact of authorized grapevinefungicides on EPNs, focusing on the survival of populations andsublethal effects on their virulence. We investigated the compatibilityof two EPN populations (Steinernema feltiae 107 and S. carpocapsae‘All’) with three organic production-approved products (Bacilluspumilus, sulfur, and copper oxychloride) and two synthetic chemicals(Trifloxystrobin and Mancozeb). Our findings revealed that the viabilityof S. feltiae 107 was reduced when exposed to sulfur and copperoxychloride, and its virulence was affected by copper oxychlorideand Mancozeb, although only two days after exposure and with nosignificant differences for larval mortality at five days.In contrast, S. carpocapsae ‘All’ exhibited full compatibilitywith all five fungicides, with no impact on its viability or virulence.Consequently, our results suggested that the evaluated fungicidescould be co-applied on both EPN populations if they were employedon the same day. However, further research on multi-targetinteractions is needed to ensure the successful implementation ofthis kind of co-applicationThe Erasmus+ - KA1 Erasmus Mundus Joint Master Degrees Program of the European Commission under the PLANT HEALTH Project supported Elizabeth Carpentero’s stage at ICVV. The predoctoral contract FPI-UR-2022 (University of La Rioja) supported Miguel Puelles. This study was also funded by the Ministry of Science and Innovation, grant PID 2019-104112RBI00 (MCIN/AEI/10.13039/50110001103). This study forms part of the AGROALNEXT programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1).Peer reviewe

Las bacterias simbiontes de los nematodos entomopatógenos como fuente de nuevos antibióticos

El uso de microrganismos productores de antibióticos para prevenir enfermedades se remonta milenios atrás. Hace más de 2000 años, en China, Serbia, Grecia y/o Egipto ya se usaban cataplasmas de pan mohoso para tratar heridas abiertas. Sin embargo, la explosión de su uso y el inicio de “la era de los antibióticos” no ocurrió hasta el descubrimiento de la penicilina en 1928 con los estudios llevados a cabo por Alexander Fleming con el hongo Penicillium notatum

Optimización de la QoE de un servicio de vídeo streaming en un entorno celular

The rising traffic demand in mobile communications networks, as well as the increase in the number of available services and the expectations of users have led operators to seek new techniques to optimize mobile networks. In this way, traditional optimization techniques, based on improving the quality of service offered to users, have given way to new techniques based on improving the quality of experience (QoE) perceived by users. In this work, a study to improve the QoE perceived by the users in a real time video streaming service from the optimization of the transmission buffer size of the RLC (Radio Link Control) layer is presented. The optimization, which has been carried out in a simulated cellular environment, has been performed for two different system bandwidth values, thus proving the relationship between the quality perceived by the users, the optimal buffer size and the available bandwidth.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Influence of the Washing Process and the Time of Fruit Harvesting throughout the Day on Quality and Chemosensory Profile of Organic Extra Virgin Olive Oils

In recent years, there has been a growing demand for organic extra virgin olive oils (OEVOOs) as quality products with greater added value. The aim of the present work was to determine whether the washing process and time of harvesting (morning or afternoon) plays an important role in the quality of Picual OEVOOs by studying quality parameters (degree of acidity, peroxide value, K232, K270, oxidative stability), and volatile and sensory profiles. Olive fruits were harvested at three maturity stages and within each phase at two times of the day (morning and afternoon). Then, samples were divided into two blocks (washed and unwashed). Volatile profile was obtained by headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Regarding the physicochemical quality parameters, sensory and volatile profiles, there were no differences between the oils produced under the two treatments applied (washed/non-washed). However, the time of harvesting (morning or afternoon) did influence the volatile and sensory profile, with higher values in the oils obtained from fruits harvested in the morning, being statistically significant for the families of aldehydes, hydrocarbures and lactones. Besides, the olives harvested during the mornings gave rise to oils with higher values in the green and apple fruit attributes.Junta de Andalucía US-138083

Desarrollo de un módulo para fortalecer funciones ejecutivas en un grupo de estudiantes universitarios

El objetivo general de esta investigación consistió en proponer acciones educativas relacionadas con el desarrollo y fortalecimiento de las funciones ejecutivas de los estudiantes de la Escuela de Ciencias de la Educación (ECE) de la Universidad Estatal a Distancia, en Costa Rica. Esta fue una investigación con enfoque mixto, bajo un diseño transformativo secuencial, en el que se trabajó con una muestra por conveniencia de 23 estudiantes. Se determinaron las características del desarrollo de las funciones ejecutivas de los participantes del estudio y a partir de estas se diseñó: un módulo de acompañamiento virtual para el fortalecimiento de las funciones ejecutivas involucradas en las actividades académicas típicas de su programa educativo. El estudio involucró tres etapas: la primera consistió en una evaluación psicométrica de las funciones ejecutivas con los tests psicométricos TESEN y ANILLAS; la segunda etapa fue la aplicación del módulo de formación y la tercera etapa implicó una segunda aplicación de los test aplicados previamente y del test PORTEUS y de un instrumento de autovaloración de las funciones ejecutivas. Dentro de los resultados más importantes, se logró detectar un aumento en el nivel de desarrollo de las funciones ejecutivas después del módulo de acompañamiento, con una diferencia de hasta 2,2 puntos; es decir, el grupo pasó de un nivel de desarrollo medio-bajo a un nivel medio en estas funciones

Desarrollo de un módulo para fortalecer funciones ejecutivas en un grupo de estudiantes universitarios

El objetivo general de esta investigación consistió en proponer acciones educativas relacionadas con el desarrollo y fortalecimiento de las funciones ejecutivas de los estudiantes de la Escuela de Ciencias de la Educación (ECE) de la Universidad Estatal a Distancia, en Costa Rica. Esta fue una investigación con enfoque mixto, bajo un diseño transformativo secuencial, en el que se trabajó con una muestra por conveniencia de 23 estudiantes. Se determinaron las características del desarrollo de las funciones ejecutivas de los participantes del estudio y a partir de estas se diseñó: un módulo de acompañamiento virtual para el fortalecimiento de las funciones ejecutivas involucradas en las actividades académicas típicas de su programa educativo. El estudio involucró tres etapas: la primera consistió en una evaluación psicométrica de las funciones ejecutivas con los tests psicométricos TESEN y ANILLAS; la segunda etapa fue la aplicación del módulo de formación y la tercera etapa implicó una segunda aplicación de los test aplicados previamente y del test PORTEUS y de un instrumento de autovaloración de las funciones ejecutivas. Dentro de los resultados más importantes, se logró detectar un aumento en el nivel de desarrollo de las funciones ejecutivas después del módulo de acompañamiento, con una diferencia de hasta 2,2 puntos; es decir, el grupo pasó de un nivel de desarrollo medio-bajo a un nivel medio en estas funciones

War in the darkness: Association of semiochemicals and entomopathogens to control wireworms

Wireworms (Coleoptera: Elateridae) are generalist insect pests attacking a wide range of plants, causing significant damages in agriculture. They feed on seeds, roots or crown and are particularly impactful on young seedlings. Wireworms locate their hosts using different cues including Volatiles Organic Compounds (VOCs) released in the rhizosphere and guiding the larvae to an appropriate host. In this study, we aimed at developing an Attract-and-kill strategy by setting up two distinct objectives : (1) comparing the attraction potential of different semiochemicals and (2) identify strains of entomopathogenic fungi and nematodes that are efficient in killing wireworms. Plant natural extracts were encapsulated in alginate beads and were shown to attract up to 76% of the tested wireworms, during behavioral assays performed in two-way olfactometers. We then performed volatile collection on these alginate beads and revealed that beads released a blend of eight VOCs, of which acetoin was the one released in higher quantity. Finally, the virulence of twelve strains of entomopathogenic fungi and eleven strains of entomopathogenic nematodes was evaluated. Two species of Metarhizium and one species of Ophiocordyceps were the most virulent against wireworms, leading to mortality levels of 39%, 50% and 57%, respectively. Three entomopathogenic nematodes strains of species Heterorhabditis bacteriophora were highly effective in killing wireworms (88 %, 53 %, and 53 % of mortality). The encapsulation of natural extracts in alginate beads appears to be a promising lure to manipulate wireworms behavior, while the co-encapsulation with entomopathogenic fungi and nematodes remains the major challenge for the development of a new Attract-and-kill strategyNEMACO