Ant brood function as life preservers during floods.

Social organisms can surmount many ecological challenges by working collectively. An impressive example of such collective behavior occurs when ants physically link together into floating 'rafts' to escape from flooded habitat. However, raft formation may represent a social dilemma, with some positions posing greater individual risks than others. Here, we investigate the position and function of different colony members, and the costs and benefits of this functional geometry in rafts of the floodplain-dwelling ant Formica selysi. By causing groups of ants to raft in the laboratory, we observe that workers are distributed throughout the raft, queens are always in the center, and 100% of brood items are placed on the base. Through a series of experiments, we show that workers and brood are extremely resistant to submersion. Both workers and brood exhibit high survival rates after they have rafted, suggesting that occupying the base of the raft is not as costly as expected. The placement of all brood on the base of one cohesive raft confers several benefits: it preserves colony integrity, takes advantage of brood buoyancy, and increases the proportion of workers that immediately recover after rafting.

Stage of change of cigarette smoking in drug dependent patients

Résumé En Suisse, les programmes de désaccoutumance au tabac se réfèrent généralement au modèle de préparation au changement de Prochaska et DiClemente (1983), Les patients atteints de maladies somatiques liées au tabagisme comme les pathologies cardiovasculaires ou pulmonaires accèdent facilement à ces programmes, contrairement aux patients présentant une dépendance à des drogues illicites. La prévalence de fumeurs dans cette population est pourtant élevée et les problèmes engendrés par le tabac sont importants, non seulement d'un point de vue individuel mais aussi en terme de santé publique. Il est par conséquent intéressant d'évaluer la motivation concernant la désaccoutumance au tabac de patients toxicomanes entreprenant un sevrage de drogues illicites. Dans cette étude, nous avons évalué les stades de préparation au changement concernant la dépendance au tabac chez 100 patients toxicomanes hospitalisés sur un mode volontaire dans le cadre d'un programme de sevrage à des drogues illégales. L'évaluation s'est faite à l'aide d'un auto-questionnaire dont les résultats indiquent qu'une minorité de patients sont décidés à interrompre la consommation de tabac. En effet, seul 15% des patients se trouvaient aux stades de contemplation ou de décision. De plus, 93% des sujets considéraient l'arrêt du tabac comme difficile ou très difficile. Ces données montrent qu'il existe un décalage important entre la motivation relative au sevrage de drogues illégales et la motivation liées à l'arrêt du tabac. En effet, malgré leur motivation élevée pour se sevrer de drogues illicites, la proportion de patients restant au stade de précontemplation concernant la désaccoutumance au tabac reste élevée. Diverses hypothèses permettent d'expliquer ces résultats, notamment la perception que la désaccoutumance au tabac est plus difficile à réaliser que le sevrage de substances illicites. Abstract Nicotine cessation programmes in Switzerland, which are commonly based on the stage of change model of Prochaska and DiClemente (1983), are rarely offered to patients with illicit drug dependence. This stands in contrast to the high smoking rates and the heavy burden of tobacco-related problems in these patients. The stage of change was therefore assessed by self-administered questionnaire in 100 inpatients attending an illegal drug withdrawal programme. Only 15% of the patients were in the contemplation or decision stage. 93% considered smoking cessation to be difficult or very difficult. These data show a discrepancy between the motivation to change illegal drug consumption habits and the motivation for smoking cessation. The high pro-portion of patients remaining in the precontemplation stage for smoking cessation, in spite of their motivation for illicit drug detoxification, may be due to the perception that cessation of smoking is more difficult than illicit drug abuse cessation.

Successful therapy for a patient with an infected ascending aortic graft and sternal osteomyelitis without graft removal.

Objective: Following open-heart surgery, sternal osteomyelitis or infection of the graft may be a serious complication with high mortality rates. The recommended treatment of an infected graft is its explantation. Because of the poor performance status of the patient, this may not always be an option. We report a successful treatment concept without removal of the infected graft. Methods: The infected ascending aortic graft and the remaining sternum of a critically ill 60-year-old man were covered with a bilateral pectoralis muscle flap. Results: Postoperatively, the laboratory test values normalized and the patient was discharged 1 month after the intervention. One year after surgery, the patient was in good condition and the examination showed no signs of infection. Conclusion: The thus demonstrated treatment concept with insertion of well-vascularized tissues in combination with a specific antibiotic regime in our hands proved to be an additional option for the successful management of life-threatening infections of a sternal osteomyelitis in combination of an infected aortic graft.

Biology of Triatoma klugi Carcavallo, Jurberg, Lent & Galvão 2001 (Heteroptera: Reduviidae) under Laboratory Conditions: Effects of Distinct Blood Sources and Susceptibility to Trypanosoma cruzi and Trypanosoma rangeli

The life cycle of Triatoma klugi Carcavallo, Jurberg, Lent & Galvão 2001 was compared under laboratory conditions using two groups of the F1 generation obtained from field-collected bugs. Among the 100 nymphs weekly fed on mice (Group A) or chicken (Group B), 77% of Group A and 67% of Group B reached the adult stage, and the mean time from the first nymphal stage to adult was 190.08 ± 28.31 days and 221.23 ± 40.50, respectively. The average span in days for each stage per group and the number of blood meals required for each stage were also evaluated. The overall mortality rate was 23% and 33% for Groups A and B, respectively. The mean number of eggs laid per month in a three-month period was of 56.20, 51.70 and 73.20 for Group A, and 64.50, 53.50 and 38.71 for Group B. Despite the blood source, comparative analysis revealed no statistically significant differences in the life cycle of T. klugi under laboratory conditions. Infection rates over 60% were observed for both Trypanosoma cruzi strains tested. Even revealing high infection rates of the hemolymph by T. rangeli strains, T. klugi revealed no salivary gland infections and was not able to transmit the parasite.

Maps as risk mitigation tools. Adaptation of the Swiss hazard assessment and mapping methodology to a Moroccan site: Beni Mellal

Dans le contexte climatique actuel, les régions méditerranéennes connaissent une intensification des phénomènes hydrométéorologiques extrêmes. Au Maroc, le risque lié aux inondations est devenu problématique, les communautés étant vulnérables aux événements extrêmes. En effet, le développement économique et urbain rapide et mal maîtrisé augmente l'exposition aux phénomènes extrêmes. La Direction du Développement et de la Coopération suisse (DDC) s'implique activement dans la réduction des risques naturels au Maroc. La cartographie des dangers et son intégration dans l'aménagement du territoire représentent une méthode efficace afin de réduire la vulnérabilité spatiale. Ainsi, la DDC a mandaté ce projet d'adaptation de la méthode suisse de cartographie des dangers à un cas d'étude marocain (la ville de Beni Mellal, région de Tadla-Azilal, Maroc). La méthode suisse a été adaptée aux contraintes spécifiques du terrain (environnement semi-aride, morphologie de piémont) et au contexte de transfert de connaissances (caractéristiques socio-économiques et pratiques). Une carte des phénomènes d'inondations a été produite. Elle contient les témoins morphologiques et les éléments anthropiques pertinents pour le développement et l'aggravation des inondations. La modélisation de la relation pluie-débit pour des événements de référence, et le routage des hydrogrammes de crue ainsi obtenus ont permis d'estimer quantitativement l'aléa inondation. Des données obtenues sur le terrain (estimations de débit, extension de crues connues) ont permis de vérifier les résultats des modèles. Des cartes d'intensité et de probabilité ont été obtenues. Enfin, une carte indicative du danger d'inondation a été produite sur la base de la matrice suisse du danger qui croise l'intensité et la probabilité d'occurrence d'un événement pour obtenir des degrés de danger assignables au territoire étudié. En vue de l'implémentation des cartes de danger dans les documents de l'aménagement du territoire, nous nous intéressons au fonctionnement actuel de la gestion institutionnelle du risque à Beni Mellal, en étudiant le degré d'intégration de la gestion et la manière dont les connaissances sur les risques influencent le processus de gestion. L'analyse montre que la gestion est marquée par une logique de gestion hiérarchique et la priorité des mesures de protection par rapport aux mesures passives d'aménagement du territoire. Les connaissances sur le risque restent sectorielles, souvent déconnectées. L'innovation dans le domaine de la gestion du risque résulte de collaborations horizontales entre les acteurs ou avec des sources de connaissances externes (par exemple les universités). Des recommandations méthodologiques et institutionnelles issues de cette étude ont été adressées aux gestionnaires en vue de l'implémentation des cartes de danger. Plus que des outils de réduction du risque, les cartes de danger aident à transmettre des connaissances vers le public et contribuent ainsi à établir une culture du risque. - Severe rainfall events are thought to be occurring more frequently in semi-arid areas. In Morocco, flood hazard has become an important topic, notably as rapid economic development and high urbanization rates have increased the exposure of people and assets in hazard-prone areas. The Swiss Agency for Development and Cooperation (SADC) is active in natural hazard mitigation in Morocco. As hazard mapping for urban planning is thought to be a sound tool for vulnerability reduction, the SADC has financed a project aimed at adapting the Swiss approach for hazard assessment and mapping to the case of Morocco. In a knowledge transfer context, the Swiss method was adapted to the semi-arid environment, the specific piedmont morphology and to socio-economic constraints particular to the study site. Following the Swiss guidelines, a hydro-geomorphological map was established, containing all geomorphic elements related to known past floods. Next, rainfall / runoff modeling for reference events and hydraulic routing of the obtained hydrographs were carried out in order to assess hazard quantitatively. Field-collected discharge estimations and flood extent for known floods were used to verify the model results. Flood hazard intensity and probability maps were obtained. Finally, an indicative danger map as defined within the Swiss hazard assessment terminology was calculated using the Swiss hazard matrix that convolves flood intensity with its recurrence probability in order to assign flood danger degrees to the concerned territory. Danger maps become effective, as risk mitigation tools, when implemented in urban planning. We focus on how local authorities are involved in the risk management process and how knowledge about risk impacts the management. An institutional vulnerability "map" was established based on individual interviews held with the main institutional actors in flood management. Results show that flood hazard management is defined by uneven actions and relationships, it is based on top-down decision-making patterns, and focus is maintained on active mitigation measures. The institutional actors embody sectorial, often disconnected risk knowledge pools, whose relationships are dictated by the institutional hierarchy. Results show that innovation in the risk management process emerges when actors collaborate despite the established hierarchy or when they open to outer knowledge pools (e.g. the academia). Several methodological and institutional recommendations were addressed to risk management stakeholders in view of potential map implementation to planning. Hazard assessment and mapping is essential to an integrated risk management approach: more than a mitigation tool, danger maps represent tools that allow communicating on hazards and establishing a risk culture.

Susceptibility of spiny rats (Proechimys semispinosus) to Leishmania (Viannia) panamensis and Leishmania (Leishmania) chagasi

The role of Proechimys semispinosus as reservoir of Leishmania (Viannia) panamensis on the Colombian Pacific coast was experimentally evaluated. The susceptibility to L. chagasi also was assessed to determine the utility of this rodent as a model for studying reservoir characteristics in the laboratory. Wild-caught animals were screened for natural trypanosomatid infections, and negative individuals were inoculated intradermally (ID) in the snout or feet with 10(7) promastigotes of L. panamensis. L. chagasi was inoculated intracardially (10(7) promastigotes) or ID in the ear (10(8) promastigotes). PCR-hybridization showed that 15% of 33 spiny rats were naturally infected with L. Viannia sp. Animals experimentally infected with L. panamensis developed non-ulcerated lesions that disappeared by the 7th week post-infection (p.i.) and became more resistant upon reinfection. Infectivity to sand flies was low (1/20-1/48 infected/fed flies) and transient, and both culture and PCR-hybridization showed that L. panamensis was cleared by the 13th week p.i. Animals inoculated with L. chagasi became subclinically infected and were non-infective to sand flies. Transient infectivity to vectors of spiny rats infected with L. panamensis, combined with population characteristics, e.g., abundance, exploitation of degraded habitats and high reproductive rates, could make them epidemiologically suitable reservoirs.

Immunocompetence and nestling survival in the house martin: the tasty chick hypothesis

In altricial birds post-fledging survival is usually positively related to nestling body mass. A large number of studies have shown that the latest hatched chick is the more likely to die, even if food is abundant. Here we suggest that ectoparasites may be a key factor in the evolution and the maintenance of the establishment of weight hierarchies within broods. We prepose the hypothesis that weight hierarchies within broods may be adaptive if the chick in poor condition is the one with the least efficient immune system within a nest. In this case parasites would preferentially feed on such a "tasty chick", because it would allow high reproductive rates for the parasites, without negatively affecting the survival of the other nestlings. This could prevent entire nest failure of the brood or allow the other chicks to grow more efficiently. This hypothesis was investigated in a colony of house martins Delichon urbica. We predicted that immunocompetence was positively correlated with body condition, and that nestlings dying before hedging should have lower immune responses when challenged with an antigen. T-cell immune response to an experimentally injected antigen was strongly positively related to body condition. Non-surviving chicks had low body condition and a weak immune response. The implications of these results are discussed in the context of the adaptive significance of hatching asynchrony.

Regional variation in sex ratios and sex allocation in androdioecious Mercurialis annua.

In androdioecious metapopulations, where males co-occur with hermaphrodites, the absence of males from certain populations or regions may be explained by locally high selfing rates, high hermaphrodite outcross siring success (e.g. due to high pollen production by hermaphrodites), or to stochastic processes (e.g. the failure of males to invade populations or regions following colonization or range expansion by hermaphrodites). In the Iberian Peninsula and Morocco, the presence of males with hermaphrodites in the wind-pollinated androdioecious plant Mercurialis annua (Euphorbiaceae) varies both among populations within relatively small regions and among regions, with some regions lacking males from all populations. The species is known to have expanded its range into the Iberian Peninsula from a southern refugium. To account for variation in male presence in M. annua, we test the following hypotheses: (1) that males are absent in areas where plant densities are lower, because selfing rates should be correspondingly higher; (2) that males are absent in areas where hermaphrodites produce more pollen; and (3) that males are absent in areas where there is an elevated proportion of populations in which plant density and hermaphrodite pollen production disfavour their invasion. We found support for predictions two and three in Morocco (the putative Pleistocene refugium for M. annua) but no support for any hypothesis in Iberia (the expanded range). Our results are partially consistent with a hypothesis of sex-allocation equilibrium for populations in Morocco; in Iberia, the absence of males from large geographical regions is more consistent with a model of sex-ratio evolution in a metapopulation with recurrent population turnover. Our study points to the role of both frequency-dependent selection and contingencies imposed by colonization during range expansions and in metapopulations.

Beyond sepsis pathophysiology with cytokines: what is their value as biomarkers for disease severity?

Sepsis is a major challenge in medicine. It is a common and frequently fatal infectious condition. The incidence continues to increase, with unacceptably high mortality rates, despite the use of specific antibiotics, aggressive operative intervention, nutritional support, and anti-inflammatory therapies. Typically, septic patients exhibit a high degree of heterogeneity due to variables such as age, weight, gender, the presence of secondary disease, the state of the immune system, and the severity of the infection. We are at urgent need for biomarkers and reliable measurements that can be applied to risk stratification of septic patients and that would easily identify those patients at the highest risk of a poor outcome. Such markers would be of fundamental importance to decision making for early intervention therapy or for the design of septic clinical trials. In the present work, we will review current biomarkers for sepsis severity and especially the use of cytokines as biomarkers with important pathophysiological role.

Naturally acquired antibodies to merozoite surface protein (MSP)-1(19) and cumulative exposure to Plasmodium falciparum and Plasmodium vivax in remote populations of the Amazon Basin of Brazil

To infer recent patterns of malaria transmission, we measured naturally acquired IgG antibodies to the conserved 19-kDa C-terminal region of the merozoite surface protein (MSP)-1 of both Plasmodium vivax (PvMSP-1(19)) and Plasmodium falciparum (PfMSP-1(19)) in remote malaria-exposed populations of the Amazon Basin. Community-based cross-sectional surveys were carried out between 2002 and 2003 in subjects of all age groups living along the margins of the Unini and Jaú rivers, Northwestern Brazil. We found high prevalence rates of IgG antibodies to PvMSP-1(19) (64.0 - 69.6%) and PfMSP-1(19) (51.6 - 52.0%), with significant differences in the proportion of subjects with antibodies to PvMSP-1(19) according to age, place of residence and habitual involvement in high-risk activities, defining some groups of highly exposed people who might be preferential targets of malaria control measures. In contrast, no risk factor other than age was significantly associated with seropositivity to PfMSP-1(19). Only 14.1% and 19.3% of the subjects tested for antibodies to PvMSP-1(19) and PfMSP-1(19) in consecutive surveys (142 - 203 days apart) seroconverted or had a three fold or higher increase in the levels of antibodies to these antigens. We discuss the extent to which serological data correlated with the classical malariometric indices and morbidity indicators measured in the studied population at the time of the seroprevalence surveys and highlight some limitations of serological data for epidemiological inference.

Breeding sites of Culicoides pachymerus Lutz in the Magdalena River basin, Colombia

The breeding sites of Culicoides pachymerus are described for the first time in western Boyacá Province, Colombia, where this species is a public health problem. In addition to being a nuisance due to its enormous density and its high biting rates, C. pachymerus cause dermatological problems in the human population. Analysis of microhabitats by the sugar flotation technique and the use of emergence traps allowed us to recover 155 larvae of Culicoides spp and 65 adults of C. pachymerus from peridomiciliary muddy substrates formed by springs of water and constant rainwater accumulation. These important findings could aid in the design of integrated control meas-ures against this pest.

Mansonella ozzardi in Amazonas, Brazil: prevalence and distribution in the municipality of Coari, in the middle Solimões River

This study investigated some epidemiological aspects of the Mansonella ozzardi in municipality of Coari, Amazonas. Clinical symptoms were correlated with the filarial infection and the parasitic infection rates (PIR) were estimated in simuliid vectors. The general M. ozzardi human prevalence rate was 13.3% (231/1733), of which 10.2% (109/1069) were from the urban area and 18.4% (122/664) from the rural area. The prevalence rates were higher in men (14.5% urban and 19.7% rural) than in women (6.7% urban and 17.2% rural) and occurred in most age groups. The indices of microfilaremics were higher in people > 51 years old (26.9% urban and 61.5% rural). High prevalence rates were observed in retired people (27.1% urban area), housewives and farmer (41.6% and 25%, respectively, in rural area). The main clinical symptoms were joint pains and sensation of leg coldness. Only Cerqueirellum argentiscutum (Simuliidae) transmits M. ozzardi in this municipality (PIR = 5.6% urban and 7.1% rural). M. ozzardi is a widely distributed parasitic disease in Coari. Thus, temporary residency in the region of people from other localities involved with the local gas exploitation might be a contributing factor in spreading the disease.

Rescue treatment with terlipressin in children with refractory septic shock: a clinical study

INTRODUCTION Refractory septic shock has dismal prognosis despite aggressive therapy. The purpose of the present study is to report the effects of terlipressin (TP) as a rescue treatment in children with catecholamine refractory hypotensive septic shock. METHODS We prospectively registered the children with severe septic shock and hypotension resistant to standard intensive care, including a high dose of catecholamines, who received compassionate therapy with TP in nine pediatric intensive care units in Spain, over a 12-month period. The TP dose was 0.02 mg/kg every four hours. RESULTS Sixteen children (age range, 1 month-13 years) were included. The cause of sepsis was meningococcal in eight cases, Staphylococcus aureus in two cases, and unknown in six cases. At inclusion the median (range) Pediatric Logistic Organ Dysfunction score was 23.5 (12-52) and the median (range) Pediatric Risk of Mortality score was 24.5 (16-43). All children had been treated with a combination of at least two catecholamines at high dose rates. TP treatment induced a rapid and sustained improvement in the mean arterial blood pressure that allowed reduction of the catecholamine infusion rate after one hour in 14 out of 16 patients. The mean (range) arterial blood pressure 30 minutes after TP administration increased from 50.5 (37-93) to 77 (42-100) mmHg (P < 0.05). The noradrenaline infusion rate 24 hours after TP treatment decreased from 2 (1-4) to 1 (0-2.5) microg/kg/min (P < 0.05). Seven patients survived to the sepsis episode. The causes of death were refractory shock in three cases, withdrawal of therapy in two cases, refractory arrhythmia in three cases, and multiorgan failure in one case. Four of the survivors had sequelae: major amputations (lower limbs and hands) in one case, minor amputations (finger) in two cases, and minor neurological deficit in one case. CONCLUSION TP is an effective vasopressor agent that could be an alternative or complementary therapy in children with refractory vasodilatory septic shock. The addition of TP to high doses of catecholamines, however, can induce excessive vasoconstriction. Additional studies are needed to define the safety profile and the clinical effectiveness of TP in children with septic shock.

Intra- and intersexual selection and their potential consequences on fitness-relevant traits in several fish species

Résumé : Les mécanismes de sélection sexuelle, en particulier la compétition entre mâles (sélection inter-sexuelle) et le choix des femelles (sélection intra-sexuelle), peuvent fortement influencer le succès reproducteur d'un individu, c'est-à-dire son nombre de descendants. On observe ainsi que les mâles dominants et les mâles élaborant des caractères sexuels secondaires marqués ont un succès reproducteur élevé. Toutefois, le succès reproducteur ne suffit pas pour garantir une contribution génétique élevée, parce que la fitness dépend également de la performance des descendants (c'est-à-dire de leur survie et de leur propre succès reproducteur). Si cette performance dépend en partie des gènes paternels, les males ont un avantage certain à signaler leur qualité aux femelles afin d'atteindre des taux de reproduction élevé. Ce mécanisme de signalisation est connu sous le nom de 'good genes hypothesis', toutefois très peu d'études ont clairement démontré le lien entre la qualité génétique des individus et la signalisation. De plus, la performance des descendants peut aussi dépendre des effets génétiques de compatibilité entre mâles et femelles ('compatible genes'). C'est-à-dire que certains allèles paternels n'apporteraient un avantage aux descendants qu'en combinaison avec certains allèles maternels. Nous avons déterminé, durant la période de reproduction, le statut de dominance des mâles pour deux espèces de poissons d'eau douce : la truite (Salmo trotta) et le vairon (Phoxinus phoxinus), puis nous avons évalué la relation entre le succès reproducteur et le statut de dominance et/ou la quantité de signalisation des caractères sexuels secondaires. Nous avons également fécondés artificiellement des oeufs de truites et de corégones (Coregonus palaea), en croisant chaque mâle avec chaque femelle (full-factorial breeding design). Ce type de design autorise la quantification précise des effets génétiques et permet de séparer les effets de 'good genes' et de 'compatible genes'. Cela a été fait sous différentes intensités de stress bactérien, ainsi que dans des conditions naturelles, et nous avons pu ainsi tester si certains indicateurs de qualité génétique des mâles ('good genes') étaient liés a) à la dominance et/ou b) à l'expression des caractères sexuels secondaires des mâles comme l'intensité mélanique ou la taille des tubercules sexuels. En outre, nous cherchons à savoir si la survie des descendants est liée à certaines combinaison des gènes du complexe d'histocompatibilité majeur (MHC) et/ou à la parenté génétique des parents, les deux traits étant soupçonnés d'avoir des influences génétique de compatibilité (`compatible genes') à la performance des descendants. Nous avons constaté que la dominance des mâles est directement liée à la taille et au poids des mâles (truites, vairons), mais également aux caractères sexuels secondaires (tubercules). De plus, les mâles vairons dominant ont eu un succès de fécondation plus élevés que les mâles subordonnés. Nous montrons que les truites et corégones mâles diffèrent dans leur qualité génétique, qui a été mesurée avéc la survie embryonnaire, le temps avant l'éclosion et enfin la croissance juvénile. Contrairement aux prédictions, la dominance (ou les traits indicatifs de dominance) n'était liée à la qualité génétique, dans aucun des traitements, et ne fonctionne donc pas comme indicateur de qualité. Par contre, la qualité génétique était liée aux caractères sexuels secondaires, particulièrement par la teinte mélanique chez les truites. Les embryons de truites issus de pères sombres survivaient mieux que ceux issus de pères clairs dans des environnements difficiles, de plus leur croissance était plus élevée lors de leur première année dans des conditions naturelles. La taille des juvéniles lors de leur première année est un trait important lié au succès dans la compétition pour des ressources telles qu'abri ou nourriture. De plus, les femelles truites peuvent augmenter la survie de leurs descendants en choisissant des mâles selon leur type de MHC ou selon leur degré de parenté. En outre, chez les corégones, la morphologie des tubercules sexuels ne semble pas signaler la qualité génétique. Nous avons également remarqué que l'exposition à des pathogènes non-létaux pouvait influencer la performance des alevins à court et long terme, probablement en affaiblissant leur système immunitaire. Cette thèse montre que les mâles diffèrent dans leur qualité génétique et que différents mécanismes de sélection inter- ou intra-sexuelle (par exemple la préférence pour des mâles sombres, pour des génotypes MHC ou pour des couples avec degré de parenté basse) pouvait avoir un effet positif sur la qualité des descendants, bien que cet effet génétique pouvait changer au cours du temps et entre différents environnements. Contrairement à nos attentes, le résultat de la compétition intra-sexuelle (la hiérarchie de dominance entre mâles) n'était pas lié à la qualité génétique individuelle ('good genes'). Dans ce sens, ce travail permet également de contribuer à l'explication du fait que la sélection sexuelle, de par sa forte sélection directionnelle, ne conduit pas à la diminution de la variance génétique, mais plutôt à la maintenance du polymorphisme génétique. Summary : Sexual selection mechanisms, especially male-male competition (inteasexual selection) and female mate choice (inteasexual selection), can strongly influence individual mating success, often resulting in dominant males and males with elaborate secondary sexual characters having higher fertilisation success. However, siring a high number of offspring alone does not guarantee high individual fitness, as fitness does also strongly depend on offspring performance (i.e. survival, fecundity). If this superiority in offspring performance depends on paternally inherited genes, the fathers are expected to signal this potential indirect benefit to females in order to attain high mating rates. This mechanism is also known as the 'good genes' hypothesis of sexual selection but until now most studies failed to conclusively show the relation of an individual genetic quality and its potential signalling traits. Further, offspring performance could also depend on compatible gene effects. These are alleles that increase offspring performance only in combination with other specific alleles. We first determined male dominance status from intrasexual competition during mating season for brown trout (Salmo trutta) and European minnows (Phoxinus phoxinus). For minnows we additionally checked if dominance and/or secondary sexual traits were linked to fertilisation success. Further, we artificially fertilised brown trout and alpine whitefish (Coregonus palaea) eggs, following full factorial breeding designs, enabling to properly measure `good gene' and `compatible gene' effects on offspring performance. This was done under different intensities of natural stressors, as well as under natural conditions. This procedure allowed us to test if the obtained male genetic quality measures (good genes effects) were indicated by a) dominance or lay traits linked to dominance and/or by b) secondary sexual characteristics such as melanin-based male skin darkness or breeding tubercles. Further, we investigated if offspring survival was linked to the MHC (major histocompatibility complex) gene combinations and/or to the parental genetic relatedness, as both traits were shown to have 'compatible gene' effects that may influence offspring performance. We found that male dominance in intrasexual competition was positively linked to body size, body weight (brown trout, minnows) but also to elaborate secondary sexual characteristics (breeding tubercles in minnows). Further, dominant minnow males did have an increased fertilisation success compared to subordinate ones. We show that brown trout and whitefish males do usually differ in their genetic quality, which was measured as embryo survival, hatching timing and finally as juvenile growth. Contrary to prediction male dominance or dominance indicating traits do not function as a quality signal as they were not linked to genetic quality. This result was constant when measuring genetic quality under different levels of natural stressors and under natural conditions (brown trout). On the other hand genetic quality seemed to be indicated by secondary sexual characteristics, specifically by melanin-based skin darkness in brown trout as brown trout embryos sired by darker fathers had increased survival rates when raised under harsh conditions and. they grew larger as juveniles after one year of growth in a natural stream, which is an important trait influencing success of juveniles in competition for hidings, food and other resources. Furthermore, brown trout females may increase the survival of their embryos when choosing males according to their MHC genotypes or to the general genetic relatedness between themselves and their potential mates. In whitefish on the other hand breeding tubercle morphology did not seem to signal genetic quality. Eventually, we saw that anon-lethal exposure to pathogens might influence short term and long term offspring performance probably by weakening an exposed individual's immune system. This thesis shows that males usually differ in their genetic quality and that different inter- or intrasexual selection mechanisms (e.g. mate selection favouring dark males, preference for MHC genotype combinations or for unrelated mates) may have strong positive effects on genetically dependent offspring performance but that such genetìc effects can change over time and environments. In contrast to our a priori expectations, the outcome of intrasexual selection, namely male dominance hierarchies, with dominant males often having high fertilisation success, was not linked to individual genetic quality (`good genes'). In this sense the present thesis may also be a helpful contribution to understand why sexual selection does not lead to rapid loss of genetic variation by strong directional selection but could even lead to the maintenance of genetic variation in natural populations.

Sandflies (Diptera: Psychodidae) in a focus of visceral leishmaniasis in White Nile, Sudan

Visceral leishmaniasis (VL) has been known to occur since the 1980s on the western bank of the White Nile River (Central Sudan), 150 km south of Khartoum, and has resulted in high mortality. The most recent outbreak of the disease in this area began in 2006. Entomological surveys were carried out during May 2008, June 2010 and May and July 2011 in the White Nile area. Sandflies were collected using Centers for Disease Control light traps and sticky oil traps in the village of Kadaba and the nearby woodland. Phlebotomus females were dissected for the presence of Leishmania promastigotes. A total of 17,387 sandflies, including six species of Phlebotomus and 10 species of Sergentomyia, were identified. The Phlebotomus species recorded were Phlebotomus orientalis, Phlebotomus papatasi, Phlebotomus bergeroti, Phlebotomus duboscqi, Phlebotomus rodhaini and Phlebotomus saevus. P. orientalis was collected in both habitats. The relative abundance of P. orientalis in the woodland habitat was higher than that recorded in the village habitat. In the woodland habitat, there was a notable increase in the relative abundance of P. orientalis during the surveys conducted in 2008 and 2010 compared to 2011. None of the 311 P. orientalis females dissected were infected with Leishmania promastigotes, although relatively high parous rates were recorded in both habitats. Based on the distribution of P. orientalis recorded in this study, this species is the most likely vector of VL in the endemic focus in the White Nile area. Further investigation is required to elucidate the seasonal abundance and distribution of the vector, as well as the transmission season of VL in both habitats so that appropriate control strategies for the vector can be designed.