Les rodonticides anticoagulants (AR) sont utilisés depuis les années 40 pour lutter contre les rongeurs. Seulement quelques années après leur commercialisation des cas de résistances ont été décrits. Les mécanismes à l'origine de ces résistances sont relativement bien décrits chez le rat brun et la souris domestique mais très peu chez le rat noir. Une étude de terrain a permis de mettre en évidence 8 mutations codantes du gène Vkorc1 chez le rat noir responsable d'un possible phénotype résistant. Actuellement, les résistances concernent surtout les AR de 1ère génération. Ainsi, les AR de 2nde génération qui sont encore actifs chez les rongeurs résistants sont de plus en plus utilisés. Cependant, en raison de leur longue rémanence tissulaire, ils sont responsables de phénomènes d'intoxication de la faune non cible. Face à ce problème majeur, une nouvelle génération d'anticoagulants plus écocompatible doit être développée. Ce travail propose une méthode pour le développement d'une 3ème génération d'AR en retravaillant la 2nde génération via le concept de la stéréochimie. En effet, les AR de 2nde génération sont un mélange de diastéréoisomères qu'il est possible de séparer. Les propriétés biologiques et toxicocinétiques des diastéréoisomères de chacune des molécules actuellement sur le marché ont été étudiées. Systématiquement, l'un des deux couples de diastéréoisomères est éliminé beaucoup plus rapidement que l'autre. Ainsi, le développement d'appâts enrichis avec le couple de diastéréoisomères les moins persistants, permettrait de réduire les risques écotoxicologiques associés à leur utilisation / Anticoagulant rodenticides (AR) have been used since the 1940s to control rodents. Only a few years after their commercialization, cases of resistance have been described. The mechanisms responsible for these resistances are relatively well described in brown rats and domestic mice but approximately unknown in black rats. A field study performed in France and Spain revealed 8 coding mutations of the Vkorc1 gene in black rat populations responsible for a possible resistant phenotype to 1st generation ARs essentially, as described for other rodents. 2nd generation ARs still active in resistant rodents are thus increasingly used. However, due to their long tissue persistence, their use is associated with an increased risk of secondary poisoning of wildlife. Faced to this major problem, a new generation of more ecofriendly anticoagulants must be developed. This work proposes a method for the development of a 3rd generation of AR by revisiting the 2nd generation AR based on the stereochemistry. Indeed, 2nd generation ARs are a mixture of diastereomers that can be easily separated. The biological and toxicokinetic properties of the diastereoisomers of each of the molecules currently on the market have been studied. Systematically, one of the two pairs of diastereoisomers is eliminated much faster than the other. Thus, the development of baits enriched with the pair of less persistent diastereoisomers would reduce the ecotoxicological risks associated with their use

In Cambodia, over 80% of the population is engaged in agricultural production, mostly in rice cultivation. The country, however, faces a lot of problems of rice crop damage. In Cambodia, rodents are considered to be one of the most important pests of rice, with the potential to cause severe damage during periodic plague events. As is seen in other developing countries, physical methods of rodent control are probably the most commonly used approaches. In general, the choice of methods varies with the availability of resources, season, the participation of farmers, the condition of the rice field, weather conditions, experience with the success of the techniques, likely level of rodent attack and other considerations. However, effective rodent control methods suiting farmers’ needs and applicable to the agricultural production environment in Cambodia are yet to be assessed. The aim of this research was to examine the socio-economic factors impacting on the implementation of several rodent control methods in comparison to the Trap-Barrier System (TBS) in order to improve rodent pest control in Cambodia. The research employed a constructivist approach in which the researcher played a role as a participant observer, to study the social setting and realities as constructed by the participants in the study sites. Rodent management was studied as a complex phenomenon, occurring within the milieu of family, village and commune life in rural Cambodia. The study looks into the beliefs and behaviours of the farming community and examines how Cambodian traditions affect the implementation of rodent management techniques and the management of rodents as a community activity. Participatory techniques were employed to gather information concerning the farmers’ assessments of the effectiveness of various rodent management options practiced in Samrong Commune. The level of adoption and adaptation of TBS in the commune was observed over a period of several years. This study is the first detailed study of farmer perceptions of alternative rodent control methods in Cambodia, especially the TBS. The study was based on long term trials involving a TBS application on a commune scale and investigations after the removal of all subsidies for purchase of materials. It was apparent that TBS use declined and eventually become limited to a few individuals who had worked closely with the project. The study also demonstrates how BBNs and Netica software can be applied as participatory tools to develop and explore the decision making structure of farmers. These tools can also be used as extension tools and can contribute to better decision making by communities. The study also shows how an understanding of traditional aspects of public goods management by communities can contribute to the design of effective contemporary solutions to problems involving the community and public goods management. In this sense its significance goes well beyond the specific context of rodent control, pest management and rice production and takes on wider significance in the field of community development generally. The study applied a mixed qualitative and quantitative approach to data collection and analysis, involving interviews, surveys, modelling, workshops, field notes, observations and document review. Five rodent control methods (TBS, rodenticide, electric fencing, netting and hunting) were found to be the most common rodent control methods used in the study sites. Some common factors were found to influence the effectiveness of these methods. Farmer participation was found to be the most widely influential factor affecting the rodent management techniques. Netting method was considered the most effective method of rodent control by farmers, as well as the method that had the best benefit-cost ratio. This technique was only found to be applicable in the wet season. In general, the effectiveness of TBS and its benefit-cost ratio was ranked fourth of the five methods, because it required high farmer participation, monitoring and maintenance as well as high material expense. Improvement of TBS can be made when it can be clearly demonstrated to farmers that TBS is an applicable method, being safe and able to catch more rats. To suit the farmers’ requirements for an effective rodent control method, TBS must be able to deal with migrating rats, situations of high rat abundance and the planting problems associated with an irregular rain regime. To achieve these conditions, some intervention policies are required in terms of research and extension support.

Les rodenticides anticoagulants (RA) constituent le principal moyen de lutte contre les rongeurs. L’exposition aux RA du renard roux et l’impact des RA sur les populations de ce prédateur sont étudiés. En France, on distingue un contexte « biocide » (BCD) où les RA sont principalement utilisés près des bâtiments et un contexte « phytopharmaceutique » (PP) où la bromadiolone (un RA) est également utilisée en plein champs contre le campagnol terrestre. La contamination des rongeurs aux RA est mesurée : 5 RA sont détectés en contexte BCD alors que la bromadiolone est la molécule majoritaire en contexte PP ; les espèces de rongeurs non ciblées par les RA étant exposées dans les2 contextes. L’exposition est maximale chez les espèces ciblées ou celles au mode de vie similaire.L’exposition du renard est évaluée par la mesure des résidus de RA dans des fèces collectées in situ.La bromadiolone est retrouvée dans 97 % des fèces positives et les RA sont plus retrouvés dans les fèces en cas de traitements PP. En contexte PP, le ratio de fèces positives augmente non linéairement avec la surface traitée dans un rayon d’1 km autour des fèces. L’impact des traitements PP sur les populations de renards est évalué (période 2003-2009, département du Doubs). Les indices d’abondance de renard mesurés sur une commune le printemps d’une année n diminuent avec l’augmentation des quantités d’appâts utilisées les années n-1 et n-2. Pendant la période suivie,la mise en place d’une lutte intégrée contre le campagnol terrestre s’est traduite par une diminution des quantités d’ AR utilisées et donc par une diminution des impacts sur les populations de renards. / Rodents are mainly controlled with anticoagulant rodenticides (AR). AR exposure and impact were studied for red fox populations. In France, we distinguish 2 contexts of AR use: “biocide” (BCD) where AR are used next to buildings and “phytopharmaceutical” (PP) where bromadiolone (an AR) is also applied in the field against the water vole. Rodent contamination to AR was characterized: 5 differentAR were detected in rodents in the BCD context while bromadiolone was predominantly found in thePP context; non target rodents being exposed in both contexts. AR contamination was the highest fortarget species or species with similar lifestyle. Red fox exposure was assessed through themeasurement of AR residues in faeces sampled in the field. ARs were detected more frequently where PP treatments occurred. Every positive faeces contained only bromadiolone except one (BCD context)with chlorophacinone. In PP context, the ratio of positive faeces varied non-linearly with the area of PPtreatments within a 1km-radius around faeces. The impact of bromadiolone PP treatments on red fox populations was assessed (period 2003–2009, Doubs department). Kilometric Abundance Index offoxes measured a year n decreased with higher treatment intensities the years n-1 and n-2. Moreoverwe have shown that a shift to preventive treatments with reduced AR use is less harmful to fox populations.

Depuis les années 50, les rodenticides anticoagulants sont couramment utilisés pour contrôler les populations de rongeurs commensaux et de prairie. De nombreux empoisonnements de la faune non cible sont répertoriés partout dans le monde. En Europe de l'Ouest notamment, la bromadiolone est utilisée de façon intensive dans les champs. Elle est le seul rodenticide autorisé en France pour contrôler les populations de Campagnol terrestre, Arvicola terrestris Sherman. Ces opérations utilisant des appâts grains de blé enterrés dans le sol sont réalisées à de larges échelles et des dizaines voire des centaines d'empoisonnements secondaires de prédateurs, dont le renard, sont répertoriés chaque année. Cette étude propose d'apporter des éléments de compréhension sur les modalités de son transfert à travers les systèmes biologiques complexes considérés dans leur intégralité.<br />Le premier objectif a été d'évaluer la variabilité environnementale de la persistance de la bromadiolone dans les appâts en conditions naturelles. Cette persistance dans les galeries de traitement est courte (demi-vie de 3 à 6 jours) et faiblement influencée par les conditions environnementales (type de sol et conditions climatiques). Cependant, elle augmente considérablement lors du stockage des appâts dans des réserves (27

Les rodenticides anticoagulants (RA) constituent le principal moyen de lutte contre les rongeurs. L'exposition aux RA du renard roux et l'impact des RA sur les populations de ce prédateur sont étudiés. En France, on distingue un contexte " biocide " (BCD) où les RA sont principalement utilisés près des bâtiments et un contexte " phytopharmaceutique " (PP) où la bromadiolone (un RA) est également utilisée en plein champs contre le campagnol terrestre. La contamination des rongeurs aux RA est mesurée : 5 RA sont détectés en contexte BCD alors que la bromadiolone est la molécule majoritaire en contexte PP ; les espèces de rongeurs non ciblées par les RA étant exposées dans les 2 contextes. L'exposition est maximale chez les espèces ciblées ou celles au mode de vie similaire. L'exposition du renard est évaluée par la mesure des résidus de RA dans des fèces collectées in situ. La bromadiolone est retrouvée dans 97 % des fèces positives et les RA sont plus retrouvés dans les fèces en cas de traitements PP. En contexte PP, le ratio de fèces positives augmente non linéairement avec la surface traitée dans un rayon d'1 km autour des fèces. L'impact des traitements PP sur les populations de renards est évalué (période 2003-2009, département du Doubs). Les indices d'abondance de renard mesurés sur une commune le printemps d'une année n diminuent avec l'augmentation des quantités d'appâts utilisées les années n-1 et n-2. Pendant la période suivie, la mise en place d'une lutte intégrée contre le campagnol terrestre s'est traduite par une diminution des quantités d'AR utilisées et donc par une diminution des impacts sur les populations de renards.

Brodifacoum is a highly effective anticoagulant rodenticide that presents a secondary hazard to some non-target wildlife. The high acute toxicity of brodifacoum to mammals and birds, and its prolonged persistence in liver predicates secondary risk to predators and scavengers of poisoned rodents. Hence there is a need to improve ability to monitor and predict hazards of brodifacoum to non-targets, and optimise use patterns accordingly. Use of a less persistent anticoagulant rodenticide, diphacinone, is an alternative approach currently under investigation in New Zealand. This thesis describes a series of laboratory and pen studies that address information gaps relevant to the assessment of non-target hazards in continued use of brodifacoum, and of using diphacinone as an alternative. Non-lethal techniques for determining sublethal brodifacoum exposure in birds was investigated in chickens. Elevation of prothrombin time was a less reliable index than residual concentrations in tissues. Samples requiring less invasive procedures, such as dried blood spots or faeces, have potential to detect recent sublethal brodifacoum exposure and refinement of these indices could be useful in proactive monitoring of avian wildlife. Residual brodifacoum in eggs of sublethally-exposed hens raised further questions regarding wider non-target hazard and adverse effects on development of fertile eggs or chicks. A laboratory trial with rats found a positive correlation between residual brodifacoum concentrations in liver and the amount of brodifacoum ingested as bait. An estimated 14-22% of ingested brodifacoum was excreted in rat faeces in the period between ingestion of a lethal dose and death, indicating another potentially significant environmental pathway for brodifacoum transfer. In considering diphacinone as a less persistent alternative rodenticide to brodifacoum, evaluation of residual concentrations and persistence in pig tissues was required to estimate secondary hazard to human consumers and adequate with-holding periods for hunting feral pigs in areas where diphacinone was applied. A pen trial showed that domestic pigs were more susceptible to diphacinone toxicity, and thus primary poisoning risk, than previously estimated. Hepatic half-life of diphacinone in pigs was approximately 14 days, indicating reduced persistence in comparison to brodifacoum and enabling estimates of with-holding periods for hunting feral pigs from areas where diphacinone baits were applied. To investigate potential hazards of diphacinone use to invertebrates a trial using tree weta, a native New Zealand invertebrate, was undertaken. Weta readily ate diphacinone wax block baits with no mortality or weight loss evident, indicating low susceptibility. Residual whole-body diphacinone concentrations did not increase with the amount of diphacinone bait eaten. A simple, deterministic risk assessment suggested that, as a single secondary exposure, the maximum diphacinone concentration measured in weta would present a low risk to non-target birds. Given international recognition of the high secondary hazard and corresponding restrictions on use of brodifacoum, continued availability of brodifacoum to non-licensed users and sustained field applications for possum and rodent control in New Zealand is an exceptional use pattern. New data in this thesis suggest that baiting strategies that minimise the amount of brodifacoum available in the environment are important and regulatory review of some New Zealand brodifacoum applications should address this. In parallel, development of diphacinone as an alternative to brodifacoum should continue, as new data here confirms lower persistence in mammalian liver than brodifacoum, and also indicates low toxicity to invertebrates. However further investigation of multiple-exposure hazard and potential sublethal effects of diphacinone on non-target mammals and birds is warranted before extensive and sustained field applications of diphacinone are undertaken.