Résumé
Sextonia rubra is an Amazonian tree known for the larvicide activity of its wood extracts against Aedes aegypti. However, the lipophilic character of this extract presents an obstacle to the development of vector management products. The purpose of this study was to assess the feasibility, efficacy, and selectivity of a water-soluble formulation based on a S. rubra wood extract characterized by its larvicidal compounds rubrenolide and rubrynolide. Using reference and wild strains, larval mortality, oviposition behavior, hatching response, and fitness of mosquitoes exposed to the extract were evaluated. Laboratory eco- and cytotoxicity bioassays were performed concurrently. The extract showed larvicidal efficacy and no repulsive effect on oviposition, thus supporting its use in the treatment of breeding sites. The formulation exhibited strong acute toxicity, leading to 100% larval mortality in 2–4 days in either the dry or rainy season at a test dose of 102 µg/ml under semi-operational conditions, with residual activity maintained during the 5 weeks of testing. The formulation allowed for a noticeable gain in selectivity compared with the extract, with lower immobilization rates for Daphnia magna and Chironomus riparius, and no significant toxicity towards human cell lines (IC50 > 100 µg/ml). These results highlight the potential of the S. rubra-based formulation for the management of Ae. aegypti larvae, including strains showing resistance to conventional insecticides.
Auteurs, date et publication :
Auteurs Emmanuelle Clervil , Jean-Bernard Duchemin , Nadine Amusant , Edmond Wozniak , Didier Azam , Maïra Coke , Dominique Huteau , Rémy Le Guével , Hélène Solhi , Isabelle Dusfour , Emeline Houël
Publication : Journal of Pest Science
Date : 2024
Catégorie(s)
#INRAE #PEARLRésumé
The pathway of dense river inflows into lakes, which affects the lake water quality, is not accurately predicted by existing models. The pathway of a dense riverine inflow in a lake with a submerged canyon is analyzed based on measurements during a 4-month period of weakening lake stratification and weakening density excess between river and epilimnion. In line with models, the dense riverine inflow plunges upon entering the lake, continues as an underflow on the sloping lake bottom, and finally intrudes at its level of neutral buoyancy. Underflow and interflow velocities are O(0.1 m s-1). The river inflow is finally trapped in the pycnocline most of the time, even when the river's density excess and the lake's stratification are marginal. This trapping in the pycnocline is explained by the reduction of the inflow density excess due to the intense plunging mixing, which is an order of magnitude larger than that obtained in confined laboratory flumes. The pathway of the dense riverine inflow is affected by interactions of the underflow with the lake bottom and sedimentary processes. A canyon carved by the underflows confines and accelerates the underflow, which enhances its capacity to entrain and carry sediment. The entrainment of sediment that was previously deposited on the canyon bottom accelerates the underflow. Due to both effects, the underflow can temporarily break through the pycnocline and reach the hypolimnion. Existing models explain these observations qualitatively, but a quantitative prediction would require better parameterizations of the plunging mixing and the sedimentary processes. The pathway of river inflows into lakes is not accurately predicted by existing models. We investigate the physical processes affecting the pathway of dense riverine inflow (i.e., inflow with a density higher than lake water) into a stratified lake. We investigate the conditions under which a dense riverine inflow get trapped in the pycnocline (the layer that separates warmer surface waters from cold deep waters) or break through it. Unprecedented long records of the temporal evolution of the pathway of the riverine flow into the lake during a period of weakening riverine density excess and lake stratification are conceptualized in a model, which extends existing concepts for dense riverine inflows. The entrainment of lake waters into the riverine inflow in the plunging region is larger than predicted by laboratory studies. This explains why the riverine inflow is trapped in the pycnocline most of the time. Flow confinement by a canyon carved by the riverine inflow into the lake bottom accelerates the riverine inflow and enhance sediment entrainment capacity causing short-lived self-accelerating turbidity currents along the lake bottom that break through the pycnocline and reach deep waters. Our results allow improved estimates of oxygen replenishment or sediment deposition from riverine water. Plunging mixing into an unconfined ambient is an order of magnitude larger than in a confined ambient Pronounced plunging mixing reduces the initial density excess explaining why the inflow is mostly trapped in the pycnocline Resuspension of lake bottom sediment can cause short-lived self-accelerating turbidity currents that break through the pycnocline
Auteurs, date et publication :
Auteurs Koen Blanckaert , Love Raman Vinna , Damien Bouffard , Ulrich Lemmin , David Andrew Barry
Publication : WATER RESOURCES RESEARCH
Date : 2024
Volume : 60
Issue : 4
Catégorie(s)
#ANR-Citation #INRAE #OLARésumé
Crops and soils are essential sources of biogenic volatile organic compounds (BVOCs) from the agriculture landscape. Agricultural management practices, including species choice, tillage, fertilization, irrigation, and cover crop application, affect soil nutrient levels, crop growth, microbial density and activities, and trigger changes in BVOC emission rates from both crop and soil. A better comprehension of the emission processes and controlling factors can improve model representation, re5 duce uncertainties, and allow more accurate quantitative estimations of agricultural BVOC emissions. We summarized current knowledge on BVOC emissions from common agricultural crops (oilseed rape, wheat, maize), cover crops, and bare soil under different management practices. The current challenges for improving the representation of agricultural BVOC emissions in models and a conceptual model for estimating BVOC emissions from agricultural land surfaces are discussed.
Auteurs, date et publication :
Auteurs Yang Liu , Raluca Ciuraru , Letizia Abis , Crist Amelynck , Pauline Buysse , Alex Guenther , Bernard Heinesch , Florence Lafouge , Florent Levavasseur , Benjamin Loubet , Auriane Voyard , Raia-Silvia Massad
Date : 2024
Catégorie(s)
#INRAE #PT-RMSAuteurs, date et publication :
Auteurs Christian Pichot , Anas Azdad , Brett Choquet , Philippe Clastre , Damien Maurice
Date : 2024
Catégorie(s)
#Ecoinfo #INRAERésumé
The fungal kingdom is among the most diversified kingdoms on Earth, with estimations of up to 12 million species. However, it remains poorly understood, with only 150 000 fungal species currently described. Given the major ecological role of fungi in ecosystem functioning, these numbers stress the importance of investigating fungal diversity description across different ecosystem types. Here, we explored the spatial distribution of the soil fungal diversity on a broad geographical scale, using the French Soil Quality Monitoring Network that covers the whole French territory (2171 soils sampled along a systematic grid). Fungal alpha diversity was assessed directly from soil DNA using a meta-barcoding approach by targeting the 18S rDNA gene. The total accumulated fungal diversity across France included 136 219 operational taxonomic units (OTUs), i.e., about 1 % of worldwide soil fungal diversity (based on a maximum diversity estimate of 12 million) for a territory representing only 0.3 % of the terrestrial surface on Earth. Based on this dataset, the first extensive map of fungal alpha diversity was drawn and showed a heterogeneous and spatially structured distribution in large biogeographical patterns of 231 km radius for richness (Hill diversity of order 0) and smaller patterns of 36 km radius for dominant fungi (Hill diversity of order 2). As related to other environmental parameters, the spatial distribution of fungal diversity (Hill numbers based on different orders of diversity) was mainly influenced by local filters such as soil characteristics and land management and also by global filters such as climate conditions with various relative influences. Interestingly, cropped soils exhibited the highest pool of fungal diversity relative to forest and vineyard soils. To complement this, soil fungal OTU network interactions were calculated for the different land uses across France. They varied hugely and showed a loss of 75 % of the complexity in crop systems and grasslands compared to forests and up to 83 % in vineyard systems. Overall, our study revealed that a nationwide survey with a high spatial-resolution approach is relevant for deeply investigating the spatial distribution and determinism of soil fungal diversity. Our findings provide novel insights for a better understanding of soil fungal ecology across the 18S rDNA gene and upgrade biodiversity conservation policies by supplying representative repositories dedicated to soil fungi.
Auteurs, date et publication :
Auteurs Christophe Djemiel , Samuel Dequiedt , Walid Horrigue , Arthur Bailly , Mélanie Lelièvre , Julie Tripied , Charles Guilland , Solène Perrin , Gwendoline Comment , Nicolas P. A. Saby , Claudy Jolivet , Antonio Bispo , Line Boulonne , Antoine Pierart , Patrick Wincker , Corinne Cruaud , Pierre-Alain Maron , Sébastien Terrat , Lionel Ranjard
Publication : SOIL
Date : 2024
Volume : 10
Issue : 1
Pages : 251-273
Catégorie(s)
#Genosol #INRAERésumé
Nitrous oxide (N2O) is one of the main problematic greenhouse gases (GHG). Between 2007 and 2016, 43% of the global N2O emissions were anthropogenic and half came from agriculture. Complex redox systems and multiple drivers effects challenge predicting N2O emissions. For example, crop residue removal has been shown to have either positive, negative or neutral effects on N2O emissions. Although meta-analysis show sthat crop residue return tends to increases N2O emissions in temperate climates, they also indicate that this trend is dependent on soil properties or other management practices. Regarding how crop residue influence N2O emissions, recent studies stress the major influence of residue quality. Despite numerous existing work, how crop residue globally influence cumulatived emissions, with a GHG perspective remains difficult to evaluate due to the short duration of most studies. We hypothesized that using the whole time scale of a long term experiment covering a wide range of practices would allow to unravel the relative weight of crop residue management on N2O emissions. We compiled 1-site-10-years-8-cropping-systems experimental data and defined joint restitution cycles (109 days to 646 days) for which both cumulative emissions and key driving variables, including measures of crop residue return and quality, were defined. The analysis of the 158 restitution cycles indicated that nitrogen fertilizer rate and length of the period were the main variables explaining N2O emissions while the C:N ratio of residue was the main driver of crop residue infuence, although that influence remains limited. The weight of crop residue influence was inversely proportional to the period length, supporting the importance of considering the timescale of measurements to evaluate how crop residue influence GHG emissions.
Auteurs, date et publication :
Auteurs Paul Belleville , Frida Keuper , Fabien Ferchaud , Bruno Mary , Heinesch Bernard , Benjamin Dumont , Joël Léonard
Date : 2024
Catégorie(s)
#ACBB #ACBB Mons #INRAEAuteurs, date et publication :
Auteurs Raia Silvia Massad
Date : 1970
Catégorie(s)
#INRAE #PT-RMSRésumé
Abstract
Freshwater algae exhibit complex dynamics, particularly in meso-oligotrophic lakes with sudden and dramatic increases in algal biomass following long periods of low background concentration. While the fundamental prerequisites for algal blooms, namely light and nutrient availability, are well-known, their specific causation involves an intricate chain of conditions. Here we examine a recent massive Uroglena bloom in Lake Geneva (Switzerland/France). We show that a certain sequence of meteorological conditions triggered this specific algal bloom event: heavy rainfall promoting excessive organic matter and nutrients loading, followed by wind-induced coastal upwelling, and a prolonged period of warm, calm weather. The combination of satellite remote sensing, in-situ measurements, ad-hoc biogeochemical analyses, and three-dimensional modeling proved invaluable in unraveling the complex dynamics of algal blooms highlighting the substantial role of littoral-pelagic connectivities in large low-nutrient lakes. These findings underscore the advantages of state-of-the-art multidisciplinary approaches for an improved understanding of dynamic systems as a whole.
Auteurs, date et publication :
Auteurs Abolfazl Irani Rahaghi , Daniel Odermatt , Orlane Anneville , Oscar Sepúlveda Steiner , Rafael Sebastian Reiss , Marina Amadori , Marco Toffolon , Stéphan Jacquet , Tristan Harmel , Mortimer Werther , Frédéric Soulignac , Etienne Dambrine , Didier Jézéquel , Christine Hatté , Viet Tran-Khac , Serena Rasconi , Frédéric Rimet , Damien Bouffard
Publication : Communications Earth & Environment
Date : 2024
Volume : 5
Issue : 1
Pages : 229
Catégorie(s)
#ANR-Citation #INRAE #OLARésumé
Lentic waters are biogeochemical reactors, producing and receiving carbon (C) originally fixed by the terrestrial and aquatic biosphere, which is then buried in sediments or respired back to the atmosphere in the forms of carbon dioxide (CO
2
) and one of the more potent greenhouse gas (GHG) methane (CH
4
). Additionally, lakes serve as archives of terrestrial and aquatic carbon processes within their sediments, enabling the reconstruction of historical changes spanning thousands of years. These changes encompass alterations in land cover, indicated by pollen records, soil carbon erosion and shifts in lake productivity resulting from changes in land use and climate. Both the burial of C in lakes and the emissions of GHGs are recognised as important components of Earth's climate system, yet they remain poorly understood and constrained due to inadequate quantities and qualities of observations. In the case of GHG emissions from lakes, observations are often sporadic, failing to capture the significant spatial and temporal variations in emissions across diverse lentic systems. To address this challenge, process-based models that incorporate the interconnected biogeochemical processes occurring within lakes and their watersheds would arguably be the best tool to extrapolate from site-level observations to regional and finally global scales, to quantify the anthropogenic impact on these fluxes and to reconstruct long-term shifts in emissions and burial due to changes in land cover and climate. However, the development and evaluation of such models is hampered by the lack of observations in sufficient quality. In this project, we bring together a unique consortium of specialists in aquatic ecology, biogeochemistry, palynology, sedimentology and modelling of terrestrial and aquatic biogeochemistry. This project will put forth a national programme of systematic, long-term observations of lake GHG and C cycling processes of unmet detail, consistency and quality. First, at 40 pilot sites spanning typological and environmental gradients, there will be a comprehensive data acquisition endeavour to evaluate biological processes and mesological factors influencing the sequestration or recycling of organic carbon. This effort will be complemented with a synthesis of existing data (WP1). Second, based on well-dated sediment records, which include both newly-acquired and synthesised existing data, variability of lake C burial and their climate and land-use controls will be reconstructed over the past 150 years (WP2). For 15 of these pilot sites, reconstruction will go back until the mid-Holocene (5,000 years BP), allowing us to shed light on the anthropogenic perturbation of the C cycle in this earlier part of human history, which is commonly excluded from this type of research due to lack of information. The activities of these first two WPs will result in an open-source national database, guaranteeing valorisation of our research far beyond this project. In WP3, we will use the land surface model (LSM) ORCHIDEE C-lateral to assess C cycling in the terrestrial biosphere and the mobilisation of biospheric C into lakes, which is possible due to an explicit representation of soil C leaching and erosion processes and a downscaling scheme permitting us to assess C exports from watersheds at sub-grid scale. While LSMs are used to assess evolution of biospheric C budgets from the beginning of the Industrial Period, we will use it to hindcast the evolution since the mid-Holocene, using lake sediment records for model validation. Moreover, we will develop a new process-based lake C model supported by the database established in WPs 1 and 2, which we will couple to ORCHIDEE C-lateral to simulate lake C burial and GHG emissions in response to climate and processes in the lake watershed. This model set-up will first be used to better constrain contemporary large-scale lake GHG emissions and to disentangle the anthropogenic perturbation of these fluxes from the natural background flux. These estimates will be revolutionary, as they will allow attributing part of lake GHG emissions to anthropogenic emissions for national GHG budget reporting. Then, these models will be emulated to reconstruct evolution of lake GHG budgets and C budgets of the whole lake watershed since the mid-Holocene. While simulations will first be performed at the scales of France and Europe, the development of international partnerships to implement observations from other biomes (WP4) will finally support simulations at the global scale.
Auteurs, date et publication :
Auteurs Jean-Philippe Jenny , Laurent Millet , Ronny Lauerwald , Fanny Colas , Hélène Masclaux , Yves Prairie , Pierre Regnier , Adam A. Ali , Fabien Arnaud , Nuno Carvalhais , Vincent Chanudet , Emmanuel Chapron , Patrick Durand , Isabelle Domaizon , Etienne Dambrine , Mathieu Dellinger , David Etienne , Jérome Gaillardet , Didier Galop , David Gateuille
Publication : Research Ideas and Outcomes
Date : 2024
Volume : 10
Pages : e136661
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs Pablo Raguet , Sabine Houot , Denis Montenach , Alain Mollier , Noura Ziadi , Antoine Karam , Christian Morel
Publication : Nutrient Cycling in Agroecosystems
Date : 2024