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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. [ABSTRACT FROM AUTHOR]

The infrastructure for Analysis and Experimentation on Ecosystems (AnaEE-France) is an integrated network of the major French experimental, analytical, and modeling platforms dedicated to the biological study of continental ecosystems (aquatic and terrestrial). This infrastructure aims at understanding and predicting ecosystem dynamics under global change. AnaEE-France comprises complementary nodes offering access to the best experimental facilities and associated biological resources and data: Ecotrons, seminatural experimental platforms to manipulate terrestrial and aquatic ecosystems, in natura sites equipped for large-scale and long-term experiments. AnaEE-France also provides shared instruments and analytical platforms dedicated to environmental (micro) biology. Finally, AnaEE-France provides users with data bases and modeling tools designed to represent ecosystem dynamics and to go further in coupling ecological, agronomical, and evolutionary approaches. In particular, AnaEE-France offers adequate services to tackle the new challenges of research in ecotoxicology, positioning its various types of platforms in an ecologically advanced ecotoxicology approach. AnaEE-France is a leading international infrastructure, and it is pioneering the construction of AnaEE (Europe) infrastructure in the field of ecosystem research. AnaEE-France infrastructure is already open to the international community of scientists in the field of continental ecotoxicology. [ABSTRACT FROM AUTHOR]

Particulate organic matter is the major source of energy for most low-order streams, but a large part of this litter is buried within bed sediment during floods and thus become poorly available for benthic food webs. The fate of this buried litter is little studied. In most cases, measures of breakdown rates consist of burying a known mass of litter within the stream sediment and following its breakdown over time. We tested this method using large litter bags (15 × 15 cm) and two field experiments. First, we used litter large bags filled with Alnus glutinosa leaves (buried at 20 cm depth with a shovel) in six stations within different land-use contexts and with different sediment grain sizes. Breakdown rates were surprisingly high (0.0011–0.0188 day−1) and neither correlate with most of the physico-chemical characteristics measured in the interstitial habitats nor with the land-use around the stream. In contrast, the rates were negatively correlated with a decrease in oxygen concentrations between surface and buried bags and positively correlated with both the percentage of coarse particles (20–40 mm) in the sediment and benthic macro-invertebrate richness. These results suggest that the vertical exchanges with surface water in the hyporheic zone play a crucial role in litter breakdown. Second, an experimental modification of local sediment (removing fine particles with a shovel to increase vertical exchanges) highlighted the influence of grain size on water and oxygen exchanges, but had no effect on hyporheic breakdown rates. Burying large litter bags within sediments may thus not be a relevant method, especially in clogged conditions, due to changes induced through the burial process in the vertical connectivity between surface and interstitial habitats that modify organic matter processing. [ABSTRACT FROM AUTHOR]