Parasitoid competitive displacement and coexistence in citrus agroecosystems: linking species distribution with climate

[EN] The introduced parasitoid wasp Aphytis melinus, the most widespread natural enemy of the California red scale (Aonidiella aurantii) and the superior competitor, has displaced the native Aphytis chrysomphali from most citrus areas of the Mediterranean basin and other citrus areas all over the world. However, our extensive survey data on the scale parasitoid populations collected in 2004–2008 show that in large citrus areas of eastern Spain both parasitoids coexist. Using field data from 179 orchards spatially divided in five citrusproducing agroecosystems, we examined the mechanisms that could explain displacement or coexistence between both Aphytis species in relation to weather conditions. The distribution and abundance of the parasitoid species are related to the mean summer and winter temperatures and relative humidity of each ecosystem. The relative proportion of A. melinus is higher during the warm months, and the abundance of A. chrysomphali increases from south to north, being higher in the cooler northern areas. Aphytis melinus has displaced A. chrysomphali from hot and dry areas, whereas regions with mild summer temperatures and moderate relative humidity present the optimal conditions for the coexistence of the two parasitoids. The more negative effects of winter temperatures on A. melinus allow the earlier use of the available host resource in late winter and spring by A. chrysomphali and the coexistence of both parasitoids in the same orchard via temporal niche partitioning. We combine previous literature on the behavior of Aphytis species in the laboratory under different temperature and humidity conditions with our field results to confirm the role of spatiotemporal weather conditions and seasonal changes in host stages on the variation of Aphytis relative abundance and parasitoid coexistence.We thank Eugenia Rodrigo of the Ecosistemas Agroforestales Department of the Valencia Polytechnic University (Spain) for her help with Aphytis identification, Robert Luck from the University of California ( USA) for information on the sex ratio, and Alejandro Tena and Rosa Vercher from the Instituto Agroforestal Mediterraneo (Valencia, Spain), Maria Jesus Verdu (Instituto Valenciano de Investigaciones Agrarias, Spain), Jacques Van Alphen and Joan van Baaren from the ECOBIO Institute (Rennes, France) for their recommendations and critical review. Special thanks to all the Citrus Phytosanitary Survey staff for the field trap samples and the two anonymous reviewers who provided helpful comments on the manuscript. English corrections were carried out by Centro de Lenguas of the Valencia Polytechnic University. This work was supported by the AGL2005-07155-C03-03 project of the Spanish Ministry of Education and Science.Sorribas Mellado, JJ.; Rodríguez, R.; García Mari, F. (2010). Parasitoid competitive displacement and coexistence in citrus agroecosystems: linking species distribution with climate. Ecological Applications. 4(20):1101-1104. https://doi.org/10.1890/09-1662.1S1101110442

Effects of water soaking and/or sodium polystyrene sulfonate addition on potassium content of foods

In this study, we determined, by atomic absorption spectrophotometry, the potassium amount leached by soaking or boiling foods identified by children suffering from chronic renal failure as "pleasure food' and that they cannot eat because of their low-potassium diet, and evaluated whether addition of sodium polystyrene sulfonate resin (i.e. Kayexalate (R)) during soaking or boiling modulated potassium loss. A significant amount of potassium content was removed by soaking (16% for chocolate and potato, 26% for apple, 37% for tomato and 41% for banana) or boiling in a large amount of water (73% for potato). Although Kayexalate (R) efficiently dose-dependently removed potassium from drinks (by 48% to 73%), resin addition during soaking or boiling did not eliminate more potassium from solid foods. Our results therefore provide useful information for dietitians who elaborate menus for people on potassium-restricted diets and would give an interesting alternative to the systematic elimination of all potassium-rich foods from their diet

Hydrothermal synthesis of homogenous and size-controlled uranium-thorium oxide micro-particles for nuclear safeguards

International audienceParticle analysis is one of the key-techniques used in the field of nuclear safeguards. Beyond traditional uranium isotopy measurement, other methodologies are implemented to better characterize nuclear materials. Among them, age dating at the particle scale enables to determine the time elapsed since the last chemical step of separation/purification or enrichment. The 230Th-234U couple being one of the most common radiochronometer, there is a need for morphology and size controlled uranium-thorium mixed oxides particles that could be used as reference materials during isotopic measurements. With this aim, uranium-thorium mixed oxide microspheres were synthesized using a wet chemistry route. The hydrothermal conversion of aspartate precursors at T = 433 K led to mixed dioxide micro-particles with controlled spherical morphology and size, up to 5 mol% in thorium. In order to remove impurities, densify the micro-particles, and control the chemical form of the final compounds, heat treatments were performed under various atmospheres. Nearly stoichiometric (U,Th)O2 dioxides were obtained under reducing conditions (Ar-4%H2) while U3O8-based samples were formed under air, with thorium incorporated in the structure up to 2 mol%. Last, the homogeneity of the cation distribution in the samples was evaluated by various methods, including PERALS α-scintillation counting, as well as X-EDS and LG-SIMS analyzes of individual particles, leading to consistent results. Particularly, the relative external reproducibility (2σ) of the 232Th+/238U+ ion ratios measured at the particle scale remained below 10%, paving the way to use these mixed oxide particles in the field of nuclear safeguards

Contribution of predation to the biological control of a key herbivorous pest in citrus agroecosystems

Biological control has traditionally simplified the view of trophic relationships between herbivorous pests and their natural enemies in agriculture. The success or failure of this pest management strategy is still mainly attributed to the ability of a few key natural enemies to suppress the pest density. For example, successful regulation of the California red scale (Aonidiella aurantii), a key citrus pest, is generally credited to specific parasitoids of the Aphytis genus. Currently, research is revealing how herbivore regulation in agroecosystems can be alternatively achieved with a greater number of trophic associations within the system. The goals of the present study were as follows: i) to unravel species‐specific trophic links between A. aurantii and its natural enemies in citrus agroecosystems, and ii) to assess their contribution to control of A. aurantii. Predation and parasitism of this herbivorous pest were assessed through exclusion experiments. Species‐specific trophic links between this herbivorous pest and its natural enemies were studied using gut‐content analysis of field‐collected predators employing prey‐specific DNA molecular markers. Relative predation rates of the species involved in A. aurantii regulation were estimated. Predation was found to be the main biotic component of A. aurantii mortality, causing reductions of more than 75% in recently settled cohorts. Aonidiella aurantii DNA was detected in the digestive system of 11 species of predators. Generalist and stenophagous predators, mainly associated with other citrus pests such as aphids, proved to be the most important biological control agents of this pest. Complex trophic relationships, such as apparent competition between two key citrus pests, were revealed. The present study highlights the role of predation as biotic mortality factor of key pests in perennial agroecosystems, wherein it is a rich complex of indigenous or naturalized generalist predators that are primarily responsible for this mortality. The results herein presented may therefore offer another perspective on the biological control of one of the key world‐wide citrus pests, at least in those regions where specific parasitoids are not able to successfully regulate the scale populations.EEA ConcordiaFil: Bouvet, Juan Pedro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concordia; Argentina. Instituto Valenciano de Investigaciones Agrarias (IVIA). Centro de Protección Vegetal y Biotecnología; EspañaFil: Urbaneja, Alberto. Instituto Valenciano de Investigaciones Agrarias (IVIA). Centro de Protección Vegetal y Biotecnología; EspañaFil: Pérez‐Hedo, Meritxell. Instituto Valenciano de Investigaciones Agrarias (IVIA). Centro de Protección Vegetal y Biotecnología; EspañaFil: Monzó, César. Instituto Valenciano de Investigaciones Agrarias (IVIA). Centro de Protección Vegetal y Biotecnología; Españ

Chronic coronary syndromes without standard modifiable cardiovascular risk factors and outcomes: the CLARIFY registry

Background and Aims: It has been reported that patients without standard modifiable cardiovascular (CV) risk factors (SMuRFs—diabetes, dyslipidaemia, hypertension, and smoking) presenting with first myocardial infarction (MI), especially women, have a higher in-hospital mortality than patients with risk factors, and possibly a lower long-term risk provided they survive the post-infarct period. This study aims to explore the long-term outcomes of SMuRF-less patients with stable coronary artery disease (CAD). Methods: CLARIFY is an observational cohort of 32 703 outpatients with stable CAD enrolled between 2009 and 2010 in 45 countries. The baseline characteristics and clinical outcomes of patients with and without SMuRFs were compared. The primary outcome was a composite of 5-year CV death or non-fatal MI. Secondary outcomes were 5-year all-cause mortality and major adverse cardiovascular events (MACE—CV death, non-fatal MI, or non-fatal stroke). Results: Among 22 132 patients with complete risk factor and outcome information, 977 (4.4%) were SMuRF-less. Age, sex, and time since CAD diagnosis were similar across groups. SMuRF-less patients had a lower 5-year rate of CV death or non-fatal MI (5.43% [95% CI 4.08–7.19] vs. 7.68% [95% CI 7.30–8.08], P = 0.012), all-cause mortality, and MACE. Similar results were found after adjustments. Clinical event rates increased steadily with the number of SMuRFs. The benefit of SMuRF-less status was particularly pronounced in women. Conclusions: SMuRF-less patients with stable CAD have a substantial but significantly lower 5-year rate of CV death or non-fatal MI than patients with risk factors. The risk of CV outcomes increases steadily with the number of risk factors