Learning affects host preference in tsetse flies

Les glossines sont des vecteurs cycliques très efficaces des trypanosomoses animales. Etant généralement infectées dès le premier repas de sang, en particulier dans le cas de la maladie du sommeil, toute tendance à retourner sur la première espèce hôte rencontrée se traduirait par une augmentation de la transmission intra-spécifique du parasite au détriment de sa transmission interspécifique. Pour tester cette hypothèse, un choix entre deux hôtes (vache et varan) a été proposé en étable sous moustiquaire à des glossines marquées (Glossina palpalis gambiensis, Diptera : Glossinidae) préalablement nourries sur un de ces deux hôtes. Quatre-vingts pourcent des glossines ténérales choisirent d’exploiter la vache lorsque le choix leur fut proposé. Parmi les glossines nourries une première fois sur un des deux hôtes, une proportion significativement supérieure de glossines sont retournées sur le premier hôte rencontré. Les avantages énergétiques et les implications épidémiologiques de ce comportement dans la transmission du parasite de la maladie du sommeil du réservoir animal à l’homme sont discutés. Enfin, la question de l’impact de l’apprentissage dans l’épidémiologie des zoonoses à transmission vectorielle est posée.Tsetse flies are very efficient cyclic vectors of African trypanosomosis. Since tsetse are generally infected by the first blood meal, as in the case of sleep-ing sickness for example, any propensity to feed on the same host a second time will improve transmission within this host species, whereas transmission between host species will decrease. To test this hypothesis we presented a monitor lizard and a cow in a stable to marked tsetse flies that had first fed on one of these two hosts. 80% of the teneral flies that fed did so on the cow when provided the choice. Among the flies having feeding experience, a dis-proportionately high number of flies that had fed on one host returned to this host for the second meal. We discuss the energetic advantages of such a learn-ing behavior and its importance in sleeping sickness epidemiology. The find-ings are of relevance to the role played by such learning behavior in disease transmission by other insect vectors of zoonoses.Las moscas tse-tse son vectores cíclicos muy eficientes de la tripanosomosis africana. En vista de que las tse-tse generalmente se infectan con su primera alimentación de sangre, como por ejemplo en el caso de la enfermedad del sueño, cualquier propensión a alimentarse una segunda vez en el mismo huésped mejora la transmisión al interior de las especies huéspedes mientras que la transmisión entre especies huéspedes disminuye. Para probar esta hipótesis, presentamos una lagartija monitor y una vaca en un establo, para marcar las moscas tse-tse que se alimentan por primera vez en uno de estos huéspedes. 80% de las moscas tenerales que se alimentaron, lo hicieron en la vaca cuando la escogencia les fue propuesta. Entre las moscas que experimentaron la alimentación, un número desproporcionado de moscas que se alimentaron en uno de los huéspedes volvieron a este huésped para su segunda comida. Discutimos las ventajas energéticas de este comportamiento aprendido y su importancia en la epidemiología de la enfermedad del sueño. Estos hallazgos son relevantes para el papel que juegan estos comportamientos aprendidos en la transmisión de la enfermedad por otros insectos vectores de zoonosis

Impact of Breeders’ Milking Practices on the Sanitary Quality of She-Camel Milk in Mauritania

The aim of the study was to assess the relationships between milking practices and the sanitary quality of raw camel milk. It was conducted from May to August 2001 in Mauritania, in Trarza and Brakna areas along the Senegalese border. Improving the sanitary quality of milk is a commercial challenge since the Mauritanians consume a lot of local milk. In addition, the dairy plant “Laitière de Mauritanie” aims at producing long-life sterilized milk. A number of breeders who supplied milk to this dairy plant were surveyed and samples from their camel milk were collected for bacteriological analyses: aerobic mesophilic and coliform flora count, methylene blue reduction and resazurin tests, and Dornic acidity titration. Milk suppliers with the poorest milking practices had the worst results with regard to the sanitary quality of milk. On average, milk was little contaminated just after milking. Mean counts were 1.6 x 106 aerobic mesophilic germs/ml and 3.5 x 104 coliforms/ml. The sanitary quality of milk decreased significantly when the milk was carried from the production area to the collecting center in more than three and a half hours after milking. Results from Dornic acidity titration were not coherent with those from the other analyses. This study confirms the need to set up a farmer’s training program on milking hygiene to produce milk with organoleptic, nutritional and high sanitary quality

La pluriactivité en France

This study is about one person engaged in more than one activity, at least one free-lance activity. It was conducted based on the analysis of the 1990 income tax returns of 1.5% of households. Using it, it was possible to quantify individual multi-activity, to measure its importance as a function of population age, to know the composition of the income of the person with a multi-activity and to compare it with one who has only one job. / La présente étude s'intéresse à la pluriactivité individuelle, associant au moins une activité non salariée. Elle a été réalisée à partir de l'analyse des déclarations de revenus de 1990 d'un échantillon au 1,5 % des foyers fiscaux , et permet de quantifier la pluriactivité indivuelle, de mesurer son importance selon l'âge de la population, de connaître la composition du revenu du pluriactif, et de comparer ce revenu au monoactif

La pluriacitivité dans la région Rhône-Alpes selon les déclarations de revenus de 1990

This article is concerned with the individual multi-activity associating at least one free-lance activity. It was done based on the analysis of the 1990 income tax statements of a 1/20 sample of tax paying households in the Rhône-Alpes region and on the basis of complete statements in the several areas of the region, typical of rural areas. The goal of this study is to quantify the individual multi-activity, to measure its importance depending on the population age, to know the composition of a multi-activity income, and to compare this income to a one-activity income. / La présente étude s'intéresse à la pluriactivité individuelle, associant au moins une activité non salariée. Elle a été réalisée à partir de l'analyse des déclarations de revenus de 1990 d'un échantillon au 1/20ème des foyers fiscaux de la région Rhône-Alpes et sur la base des déclarations exhaustives dans plusieurs zones de la Région , caractéristiques des types d'espaces ruraux. Elle, permet de quantifier la pluriactivité individuelle, de mesurer son importance selon l'âge de la population, de connaître la composition du revenu du pluriactif, et comparer ce revenu au monoactif

La pluriactivité dans la région de Redon (départements 35,56 et 44)

This study is about one person engaged in more than one activity, at least one free-lance activity. It was conducted based on the analysis of the 1990 income tax returns of a representative sample of households of the Redon region. Using it, it was possible to quantify individual multi-activity, to measure its importance as a function of population age, to know the composition of the income of the person with a multi-activity and to compare it with one who has only one job. / La présente étude s'intéresse à la pluriactivité individuelle, associant au moins une activité non salariée. Elle a été réalisée à partir de l'analyse des déclarations de revenus de 1990 des foyers fiscaux sur un échantillon représentatif de cantons de la région de Redon, et permet de quantifier la pluriactivité individuelle, de mesurer son importance selon l'âge de la population, de connaître la composition du revenu du pluriactif, et comparer ce revenu au monoactif

La pluriactivité dans la région Rhône-Alpes

This study is about one person engaged in more than one activity, at least one free-lance activity. It was conducted based on the analysis of the 1990 income tax returns of a representative sample of households of the Rhône-Alpes region. Using it, it was possible to quantify individual multi-activity, to measure its importance as a function of population age, to know the composition of the income of the person with a multi-activity and to compare it with one who has only one job. / La présente étude s'intéresse à la pluriactivité individuelle, associant au moins une activité non salariée. Elle a été réalisée à partir de l'analyse des déclarations de revenus de 1990 d'un échantillon au 1/20ème des foyers fiscaux de la région Rhône-Alpes, et permet de quantifier la pluriactivité indivuelle, de mesurer son importance selon l'âge de la population, de connaître la composition du revenu du pluriactif, et comparer ce revenu au monoactif

Approach to the Diversity of Dairy Farm Systems in Reunion

The impacts of economical, institutional and technical changes on farming systems’ organization and performance differ between systems depending on initial endowments, projects, organization types and productive-system management, investment opportunities, etc. As it is difficult to apprehend exhaustively individual diversity, farm modeling through typology appears as the only way to approach farming systems’ diversity in order to assess change differentiated effects and to ensure that research and development will reflect local needs and diversity. The typology, which characterizes the diversity of dairy farm systems in Reunion, results from an iterative and progressive process that combines principles from the typology à dire d’expert (i.e. based on an expert representation of the diversity) and multivariate methods. The typology was developed from surveys and interviews of farmers, and the various actors of the dairy sector: cooperatives, development agencies, local administrators, management centers, etc

Animal Production Performance and Herd Management in Suckling Farms on Réunion Island

In Réunion, because of the insularity and the small size of farms, improving cattle farm productivity involves increas­ing technical management aspects. To analyze relationships between herd management practices and animal perform­ances, a survey was conducted in ten suckling farms, located in the Highlands, from 1999 to 2002. Three sets of 4, 8 and 3 variables, respectively, were thus extracted from the moni­toring database: animal performances (calving interval, fertil­ity rate, body weight at standard age, live meat production), farmers’ practices (grazing time per hectare and paddock, time interval between two passages, paddock size, stocking rate, feed complementation of weaned animals and lactating cows, culling rate), and environment (rainfall, herbage production, body condition score of cows). An analysis of co-inertia was carried out on the first two tables to analyze relationships between animal production performances and practices. A significant correlation was observed between the two tables. The results of the co-inertia analysis were interpreted for each farm. Beyond specific constraints, they revealed proximities between farms and herd management based on various strat­egies, which were relevant with the observed performances. A STATICO analysis was performed to assess relationships between performance parameters and environment parameters for the four studied years. It revealed that there was a stable costructure between the environment and performance tables. This suggests that practices had a highly structuring effect on animal production and that some system adjustments miti­gated the climate effects