Recherches sur l'utilisation de mesocosmes pour l'evaluation de l'impact ecotoxicologique potentiel des insecticides en milieu aquatique

SIGLEINIST T 73237 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Plan Ecophyto - Pesticides et biodiversité : premiers enseignements

Plan Ecophyto - Pesticides et biodiversité : premiers enseignement

Simulation de la réponse d hydrosystèmes continentaux (mares et rivières) à une perturbation de type toxique : effet du regroupement d entités taxonomiques sur la pertinence de l évaluation des risques écotoxicologiques

L utilisation de modèles d écosystèmes pour l évaluation des risques écotoxicologiques implique souvent l élaboration d une représentation théorique (modèle conceptuel) de l écosystème étudié. Ces modèles peuvent être détaillés ou au contraire très simplifiés. La simplification d un modèle détaillé se fait via un regroupement de variables. Ce regroupement peut être envisagé d un point de vue taxonomique, fonctionnel ou encore selon la sensibilité des compartiments biologiques à un polluant. Cette étude vise à évaluer jusqu à quel point la simplification du modèle peut être réalisée sans remettre en cause la pertinence de ses sorties en ce qui concerne l évaluation des risques écotoxicologiques. Le cas retenu est celui de la contamination ponctuelle d un écosystème aquatique par la deltaméthrine. Les données utilisées ont été obtenues lors d expériences réalisées dans des mésocosmes lentiques et lotiques. Deux outils ont été utilisés, Aquatox et TerraSys. Les modèles conceptuels ont été définis en fonction des groupes taxonomiques présents et des connaissances disponibles sur leur écologie. Avec Aquatox, des modèles simplifiés ont tout d abord été développés en regroupant ces groupes toxonomiques selon leurs caractéristiques trophiques et fonctionnelles. Les modèles ont ensuite été détaillés en distinguant des compartiments caractérisés par des sensibilités différentes par rapport à la deltaméhtrine. Un protocole pour l analyse de sensibilité des modèles développés avec Aquatox a été élaboré et mis en œuvre sur les différents modèles, ce qui permettra à l avenir de mieux cibler les paramètres qui nécessitent l acquisition d informations détaillées. Les modèles d écosystèmes lotiques et lentiques permettent de simuler correctement les compartiments en conditions normales.The use of mathematical ecosystem models for ecological risk assessment often implies to develop a theoretical representation (conceptual model) of the studied ecosystem. These models are divided into two types : detailed models and simple models. The aggregation of variables permits to simplify a detailed model into a simple one. Aggregation may be performed based on taxonomic or functional aspects, or according to the differential sensitivy of the various organisms to the same toxicant. This study aimed at evaluating at which level the simplification of the model can be carried out without questioning the relevance of the model outprunts in the context of ecological risk assessment. The data used were obtained during experiments performed in lentic and lotic mesocosms treated with the pyrethroid insecticide deltamethrin. Two softwares were used in this study, Aquatox and Terra Sys. The conceptual models were defined according to the species identified in the samples and the available knowledge on their ecology. With Aquatox highly simplified models were first developed by grouping species according to their trophic and functional characteristics. These models were then detailed by distinguishing the compartments characterized by different sensitivities to the insecticide. A multivariate method for performing sensitivity analysis of the models developed with Aquatox was developed and applied to the various models. IT permits to identify those parameters that will deserve particular attentionduring forthcoming experiments. The results showed that both lotic and lentic ecosystem models may be used to adequately simulate the compartments under control conditions.RENNES-Agrocampus-CRD (352382323) / SudocSudocFranceF

Bti sprays do not adversely affect non-target aquatic invertebrates in French Atlantic coastal wetlands

Both the increase in human mobility and climate change contribute to the globalization of vector-borne diseases. Some mosquito species are efficient disease vectors in Europe, thus increasing the risk of epidemic (re)emergence.Bacillus thuringiensis var. israelensis (Bti) is considered as the most efficient larvicide to control mosquito populations with negligible environmental impacts. However, repeated field applications of Bti over many years raise the question of possible long-term effects on non-target invertebrates with putative subsequent alterations of food webs. Environmental effects of Bti have mainly been studied in continental freshwater wetlands. Much less is known for brackish water coastal wetlands. We investigated whether repeated treatments with Bti, applied as VectoBac((R)) WG over seven consecutive years, may affect non-target invertebrate communities in wetlands of the French Atlantic coast. Particular attention was devoted to invertebrates potentially used as food sources by shorebirds and wading birds. Invertebrates were sampled in the water and sediment of control and VectoBac((R))-treated saltmarsh pools between 2006 and 2012. Taxa abundance data were used to calculate community descriptors and to analyse the potential structural changes due to VectoBac((R)) using the principal response curve method and similarity analysis. Physicochemical parameters were measured in the same pools so that homogeneity of the environmental conditions between the control and treated areas could be tested. We demonstrated that long-term use of VectoBac((R)) WG in French Atlantic coastal wetlands had no influence on the temporal evolution of the taxonomic structure and taxa abundance of non-target aquatic invertebrate communities, which is highly driven by abiotic factors. In addition, over the long term, the amount of invertebrates that could be used as food resources by birds is maintained in VectoBac((R))-treated areas.Synthesis and applications. Reduced application rate and targeted spraying of VectoBac((R)) WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis (Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac((R)). Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non-target animal communities potentially exposed to Bti. Reduced application rate and targeted spraying of VectoBac((R)) WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis (Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac((R)). Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non-target animal communities potentially exposed to Bti

Entre pollution et changement climatique, la survie des organismes du sol

Changement climatique. Les biotechnologies face à un défi de tailleLe changement climatique modifie le devenir des composés polluants dans l’environnement, ainsi que leur toxicité vis-à-vis des organismes (micro-organismes, faune, flore…) qui le peuplent. Les conséquences possibles sur la structure des communautés vivantes et leur activité peuvent avoir des répercussions sur l’ensemble de la biosphère

Le métaprogramme Adaptation au Changement Climatique de l'Agriculture et de la Forêt (ACCAF) de l'INRA

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Des menaces aux solutions

National audienc

Le métaprogramme Adaptation au Changement Climatique de l'Agriculture et de la Forêt (ACCAF) de l'INRA

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Des menaces aux solutions

National audienc

Des bioindicateurs pour évaluer l’impact ou la restauration vis-à-vis des pesticides - Diatomées

Action 9 INRA Thonon-Rennes / ONEMADes bioindicateurs pour évaluer l’impact ou la restauration vis-à-vis des pesticides - Diatomées. Colloque ONEMA Les méthodes d'évaluation de l'état des eaux: situation et perspectives dans le contexte de la DC