EnvFate

Projet: Le Bti, un insecticide biologique de plus en plus utilisé : quel est son impact au niveau environnemental (EnvFate)

Coordinateur: Dr. Cedric Bertrand
Dr. Marie Virginie-Salvia
Dr. Chandrashekhar Patil

Période: 2017-2019 (2 ans)

Zone d’Étude: Monde

Résumé: Les moustiques envahissent de plus en plus de nouveaux milieux, phénomène dû notamment à l’augmentation des échanges internationaux ainsi qu’au réchauffement climatique. L’EID Méditerranée (Entente interdépartementale pour la démoustication) a pour vocation de lutter contre la prolifération de ces moustiques dans plusieurs départements du littoral méditerranéen dont les PO. Cette action de démoustication a pour objectif principal de lutter contre les moustiques vecteurs de maladies (chikungunya,…) ce qui est un réel enjeu de santé publique. Elle vise également le confort des populations. Cette opération de démoustication est essentielle dans notre département afin d’assurer à notre territoire et à nos touristes une qualité de vie agréable. Il est donc nécessaire de trouver une stratégie de lutte contre les moustiques efficace et ayant un impact moindre sur l’environnement.

De nombreux insecticides chimiques ont été développés. Cependant, des phénomènes de résistance à ces insecticides ont été observés. De plus, depuis 1998, l’utilisation des produits de synthèse a été remise en cause. La législation et l’apparition de phénomènes de résistance aux composés traditionnels a conduit à l’utilisation du Bacillus thuringiensis israelensis (Bti). Le Bti est une bactérie utilisée par l’EID Méditerranée exclusivement pour la lutte antilarvaire en milieu urbain et naturel ; ce bio-insecticide étant très spécifique aux larves de moustiques. Aujourd’hui l’essentiel des étangs et marais du Roussillon sont démoustiqués avec ce micro-organisme. Quelques voix d’associations naturalistes se sont récemment élevées contre l’utilisation de ce produit. En effet, peu ou pas d’étude ont été réalisées à l’heure actuelle pour évaluer l’impact environnemental du Bti.

Les chercheurs du CRIOBE conscients de l’importance économique et environnementale de ce sujet ont choisi de développer une approche innovante basée sur la métabolomique afin de contribuer aux recherches permettant d’apporter des réponses quant à l’impact environnemental de ces nouveaux biopesticides. Ainsi le CRIOBE, grâce au projet Envfate financé par l’Union Européenne (MARIE SKŁODOWSKA-CURIE ACTIONS, Individual Fellowships) doit développer dans les mois à venir un outil innovant permettant de caractériser le devenir et l’impact de ce type d’insecticides en milieu lagunaire.

Source de Financement: European Union MARIE SKŁODOWSKA-CURIE ACTIONS
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 746656


ENGLISH/

Project: Study of the environmental impact of insecticides by metabolomic foot-printing approach

Introduction: Mosquitoes can carry infectious diseases from person to person and from place to place. Presence and establishment of invasive mosquito species such as Aedes aegypti and Aedes albopictus is rapidly increasing in the European environment, phenomena mostly due to the increase of international exchanges (rapid movement of people infected with the virus and competent mosquito vectors), urbanisation (high density of susceptible people, plethora of mosquito breeding sites), and the global warming (eg, the capacity of mosquitoes to transmit the virus is heavily dependent on temperature). Indeed, the presence of mosquito vectors can create a risk of an epidemic such as dengue, chikungunya or more recently the Zika virus. Sustainable vector management is the only means that effectively could prevent and control the transmission of the viruses of public health importance.

State-of-the-art: Since the appearance of the European Directive (98/8/CE) in 1998 concerning the marketing authorizations of biocides, the use of the whole synthetic insecticides was reconsidered. Indeed, it forbids, since September 2006, the use of non-approved synthetic products. Therefore, this Directive led to the increasing use of biological insecticides such as toxins (cry proteins) produced by the bacterium Bacillus thuringiensis israelensis (Bti) that kill mosquito larvae after being ingested. Thus higher mosquito population leads to higher use of Bti that ultimately builds anthropogenic burden in the southernmost part of Europe.

Objectives and overview of the action: Being a natural product, Bti producing insecticidal Cry proteins is largely assumed as “Environmentally friendly” and that it does not have any negative influence on the environment. But is Bti so harmless? To our knowledge, the environmental fate and impact of this biological substance are poorly studied and this is the objective of the proposed project. This study is really important at the environmental level as the presence of emerging pollutants in the different environment is nowadays one of the major concerns and is of critical importance to regulatory authorities. Although Bti is not yet identified as an emerging pollutant, the overuse of this biocide for invasive mosquito population control has already been pointed by environmental protection associations. Besides studying Bti, we will also examine one chemical insecticide for comparison. We will choose α-cypermethrin as it is still a lot used insecticide in the rice field treatments.

Environmental Metabolomic Footprinting (EMF) approach: EMF consists of the metabolomic data acquisition (through LC-MS) and data processing via the use of multivariate statistical analysis. We will employ EMF to know the impact of both insecticides on sediment, its resilience time, and on longer-term evidence the potential pollution biomarkers (overexpression of sediment endogenous compounds, transformation products,…). In parallel to the metabolomic analysis, a study on the presence of mixed microbial community in the test sediments will be done using a metabarcoding approach. Using metabarcoding analysis will allow evaluating the microbial community responses to the Bti biocide and therefore to evaluate its ecotoxicity. The use of omics approaches (metabarcoding and metabolomics) applied to sediment matrix is an innovative tool to assess Bti ecotoxicology and might allow the identification of potential biomarkers of Bti.

Expected Outcome: The project will allow answering to one main question: the use of biological insecticides vs a synthetic one is it the good choice to preserve the environment?

Indeed, nowadays, the evaluation of the impact of complex mixtures (biopesticides) is not possible with the guidelines proposed by the diverse organisations such as OECD (Organization for Economic Co-operation and Development) or EFSA (European Food Safety Authority). It is hence worth developing techniques like EMF. They could be then used by these latter organisations to develop successful policy framework and environment preservation initiatives as biocontrol compounds will be probably increasingly employed due to the interdiction of more and more chemical pesticides.