Studies on the sandfly fauna of Samuel Ecological Station, Porto Velho Municipality, Rondônia State, Brazil

In a study of sandfly species in the Samuel Ecological Station, in Porto Velho, Rondônia State, the following species were identified: Lutzomyia brasiliensis, L. evangelistai, L. gomezi, L. anduzei, L. flaviscutellata, L. richardwardi, L. shawi, L. umbratilis, L. yuilli yuilli, L. dendrophyla, L. puctigeniculata, L. shannoni, L. amazonensis, L. ayrozai, L. carrerai carrerai, L. claustrei, L. davisi and L. lainsoni. L. richardwardi, L. umbratilis and L. c. carrerai were the predominant species captured of man forming 60.30% of the total catch. L. richarwardi was the most frequent at ground level (29.9%), while L. umbratilis predominated in the canopy (48.5%).

Dengue in Brazil - situation, transmission and control: a proposal for ecological control

This article discusses dengue in terms of its conceptual and historical aspects, epidemiological and clinical/pathological nature, and evolution up to the present situation in Brazil. The author discusses the ecological relationship in both the production of dengue and its control. Comparison is made between traditional dengue-control programs and a proposed socially-controlled program of an ecological nature without the use of insecticides. Stress is placed on interdisciplinary technical and scientific activity, broadbased participation by communities in discussing methodological aspects involving them, and prospective evaluation comparing the communities selected for intervention and control communities with regard to clinical and subclinical dengue cases and vector infestation rates in relation to climatic, socio-economic, and behavioural factors.

The snail hosts of schistosomiasis: some evolutionary and ecological perspectives in relation to control

Despite opportunities for radiation provided by spatio-temporal isolation, the basic morphological plan of pulmonate snails has remained conservative. In consequence of the resulting dearth of morphological characters and their plasticity, there is a case for using biochemical characters such as exogenous chemicals released by the snails (e.g. amino acids) and their chemoreception niche as taxonomic aids to classify snails of medical importance. As these same chemicals are used by snails to distinguish conspecifics they could also be used as "environmental antibodies" in controlled release formulations (CRF's) designed to remove target snails in a specific, cost-effective and ecologically acceptable manner. The snails, surface-living bacteria, algae and macrophytic plants are considered as co-evolved, interactive modular systems with strong mutualistic elements. Recently, anthropogenic perturbations such as deforestation, and damming of flowing waters, have benefited these modules whereas others such as river canalization, acid deposition, accumulation of pesticide residues and eutrophication have harmed them. Research is needed to elucidate the factors which limit the growth of snails in primitive habitats, uninfluenced by man, as well as in those subject to harmful anthropogenic factors. The understanding thus gained could be applied to develop cost-effective primary health care strategies to reduce or prevent transmission of schistosomiasis and other water related diseases.

The use and mis-use of some ecological terms and concepts in epidemiology

The article discusses the current use and mis-use of ecological terms and concepts in epidemiological literature, and in special, in works dealing with zoonotic diseases. A selection of examples was taken from papers recently published on the transmission of Chagas' disease by Triatoma sordida. Proper definitions are listed, with the intent of helping non-ecologists to use those terms and concepts correctly.

Ecological interactions of visceral leishmaniasis in the state of Bahia, Brazil

The laboratory and field observations summarized in this paper on visceral leishmaniasis ecology in the State of Bahia, Brazil are based on the author's observations over the past 35 years in a number of state's foci, public health records and literature citations. The disease is endemic with epidemic outbreaks occurring every ten years and its geographical distribution is expanding rapidly in the last years. Leishmania chagasi is the main ethiologic agent of the visceral leishmaniasis but Le. amazonensis s. lato was the only leishmania isolated by other authors from some visceral leishmaniasis human cases in the state. Lutzomyia longipalpis (with one or two spots on tergites III and IV and two sized different populations) was epidemiologically incriminated as the main vector. It was found naturally infected with promastigotes, and it was infected with four species of leishmanias in the laboratory. Although the experimental transmission of Le. amazonensis by the bite of Lu. longipalpis to hamsters was performed, the author was not successful in transmitting Le. chagasi in the same way. The dog is the most important domestic source for infection of the vector, however it is not a primary reservoir. The opossum Didelphis albiventris was found naturally infected with Le. chagasi but its role as reservoir is unknown. Foxes and rodents were not found infected with leishmanias in Bahia.

Evolution, maintenance and ecological consequences of genetic caste determination in " Pogonomyrmex " harvester ants

Summary Division of labor between reproducers (queens) and helpers (workers) is the main characteristic of social insect societies and at the root of their ecological success. Kin selection models predict that phenotypic differences between queens and workers should result from environmental rather than from genetic differences. However, genetic effects on queen and worker differentiation were found in two populations-of Pogonomyrmex harvester ants. Each of the two populations is composed of two genetically distinct lineages. Queens (which can be of either lineage) generally mate with males of their own and of the alternate lineage and produce two types of female offspring, those fertilized by males of the queens' lineage which develop into queens and those fertilized by males of the alternate lineage which develop into workers. All four lineages were further suggested to be themselves of hybrid origin between-the species P: barbatus and P. rugosus, in which queens and workers do not differ genetically. In a first set of experiments, we tested if female caste determination (the differentiation into queens and workers) in the lineages was genetically hardwired and if it was associated with costs in terms of the ability to optimally allocate resources to the production of queens and workers. To this end we first mated queens of-two lineages to a single male. Queens mated to a male of the alternate lineage successfully raised worker offspring whereas queens mated to a male of their own lineage almost always failed to produce workers. This reveals that pure-lineage individuals have lost the ability to develop into workers. Second, we analyzed offspring produced by naturally mated queens. During the stage of colony founding when only workers are produced, naturally mated queens laid a high proportion of pure-lineage eggs but the large majority of these eggs failed to develop. As a consequence, the number of offspring produced by incipient colonies decreased linearly with the proportion of pure-lineage eggs laid by queens. Moreover, queens of the lineage most commonly represented in a given population produced more pure-lineage eggs, in line with the view that they mate randomly with the two types of males and indiscriminately use their sperm. Altogether these results predict frequency-dependent founding success for pairs of lineages because queens of the more common lineage will produce more pure-lineage eggs and their colonies be less successful during the stage of colony founding. To describe the distribution of populations characterized with genetic caste determination relative to the populations with environmental caste determination we genotyped queens and workers collected during a large survey of -additional populations. Genetic caste determination associated with pairs of interbreeding lineages was frequent and widespread in the studied range and we identified four additional lineages displaying genetic caste determination. Overall, there were thus eight highly differentiated lineages with genetic caste determination. These lineages always co-occurred in the same complementary lineage pairs. Three of the four lineage pairs appeared to have a common origin, while their relationship with the forth could not be resolved. The genetic survey also revealed that, in addition to being genetically isolated from one another, all eight lineages were genetically distinct from P. rugosus and P. barbatus, even when colonies of interbreeding lineages co-occurred with colonies of either putative parent at the same site. This raised the question of the mechanisms involved in the reproductive isolation between the lineages and the parental species and between the two lineages of a lineage pair. At a site where one lineage pair co-occurred with P. rugosus, we identified two pre-zygotic mechanisms (differences in timing for mating flights between P. rugosus and the lineage pair and assortative mating) and one post-zygotic mechanism (high levels of hybrid unviablility) which in combination may largely account for the reproductive isolation between the lineages and their parental species. The mechanisms accounting for the reproductive isolation between the two lineages of a lineage pair varied across lineage pairs. In one lineage pair, inter-lineage individuals exclusively occurred in the sterile worker caste, raising the possibility that inter-lineage eggs have completely lost the ability to develop into queens in this lineage pair and that there is thus no opportunity for gene flow. In each of the three remaining lineage pairs, inter-lineage queens were produced by a minority of colonies. In these lineage pairs, colonies headed by inter-lineage queens failed to grow sufficiently to produce reproductive individuals which may account for the reproductive isolation between co-occurring lineages in three lineage pairs. In conclusion, the results of this thesis show that genetic caste determination is costly but widespread in Pogonomyrmex harvester ants. Reproductive isolation among the lineages and between the lineages and the parental species as well as frequency-dependent founding success for co-occurring lineages may contribute to the persistence of this extraordinary system. Résumé La division du travail entre individus reproducteurs (les reines) et individus non-reproducteurs (ouvrières) représente la caractéristique principale des sociétés d'insectes et est à la base de leur succès écologique. Des modèles de sélection de parentèle prédisent que les différences phénotypiques entre reines et ouvrières devraient provenir d'effets environnementaux plutôt que de différences génétiques. Malgré ce fait, des effets génétiques sur la différentiation entre reines et ouvrières ont été montrés dans deux populations de fourmis moissonneuses du genre Pogonomyrmex. Chacune des deux populations est composée de deux lignées génétiquement distinctes. Les reines de chaque lignée s'accouplent en général avec des mâles de leur propre lignée ainsi qu'avec des mâles de l'autre lignée et produisent deux types d'oeufs, ceux qui sont fécondés par les mâles de leur propre lignée qui se développent en nouvelles reines et ceux qui sont fécondés par les mâles de l'autre lignée qui se développent en ouvrières. Il a été suggéré que les lignées sont elles-mêmes des hybrides entre les deux espèces P. barbatus et P. rugosus. Dans ces deux espèces, les reines et ouvrières ne sont pas génétiquement distinctes. Dans une première série d'expériences, nous avons testé si la détermination de la caste femelle (le développement en reine ou en ouvrière) est génétiquement rigide et si elle est associée à des coûts en terme de capacité à allouer de façon optimale les ressources pour la production de reines et d'ouvrières. Pour cela nous avons accouplé des reines de deux lignées avec un seul mâle. Les reines accouplées avec un mâle de l'autre lignée ont élevé de nouvelles ouvrières avec succès alors que les reines accouplées avec un mâle de leur propre lignée ont presque toujours échoué à produire des ouvrières. Ceci montre que les individus de lignée pure ont perdu la capacité de se développer en ouvrière. Deuxièmement, nous avons analysé la descendance de reines qui se sont accouplées naturellement. Durant le stade de fondation de la colonie, où seules des ouvrières sont élevées, les reines accouplées naturellement ont pondu une grande proportion d'oeufs de lignée pure mais la majorité de ces derniers ne se sont pas développés. En conséquence, le nombre de descendants produits par des colonies fondatrices diminuait linéairement avec la proportion des oeufs de lignée pure pondus par la reine en accord avec l'hypothèse que les reines s'accouplent au hasard avec les deux types de mâles et utilisent leur sperme aléatoirement. Dans l'ensemble; ces résultats prédisent un succès de fondation fréquence-dépendant pour les deux lignées, car les reines de la lignée la plus fréquente produiront .plus d'oeufs de lignée pure et leurs colonies auront moins de succès lors de la fondation de colonies par rapport aux colonies de la lignée la moins fréquente. Pour décrire la distribution des-populations caractérisées par une détermination génétique des castes par rapport aux populations caractérisées par une détermination environnementale des castes, nous avons génotypé des reines et des ouvrières qui ont été collectées lors d'une analyse de populations supplémentaires. La détermination génétique des castes associée à des croisements entre lignées est fréquente et largement répartie dans l'aire étudiée. Nous avons identifié quatre lignées supplémentaires, ayant une détermination génétique des castes, pour un total de huit lignées. Ces huit lignées forment quatre paires de lignées et on ne trouve jamais deux lignées de paires différentes, dans une population. Trois des quatre paires de lignées s'avèrent avoir une origine commune alors que leur relation avec la quatrième paire de lignées n'a pas pu être résolue. L'analyse génétique de populations supplémentaires a également révélé qu'en plus d'être génétiquement isolées les unes des autres, les huit lignées sont génétiquement distinctes de P. rugosus et P. barbatus même si les colonies d'une paire de lignées se trouvent en sympatrie avec l'une ou l'autre des espèces parentales. Ceci relève la question des mécanismes impliqués dans l'isolation reproductive entre les lignées et les espèces parentales ainsi qu'entre les deux lignées d'une paire. En étudiant un site où une paire de lignées se trouve en sympatrie avec P. rugosus, nous avons identifié deux mécanismes pré-zygotiques (des différences dans le timing du vol nuptial entre P. rugosus et les lignées et des accouplements assortis) ainsi qu'un mécanisme post-zygotique (un niveau élevé de non-viabilité des hybrides). En combinaison, ces mécanismes peuvent largement expliquer l'isolement reproductif entre les lignées et leurs espèces parentales. Les mécanismes contribuant à l'isolement reproductif entre les deux lignées d'une paire variaient entre paires de lignées. Dans une paire, les individus de génotype inter-lignée se trouvent uniquement dans la caste stérile des ouvrières, suggérant qu'il n'y a pas d'opportunité pour avoir du flux de gènes entre les deux lignées ce cette paire. Dans chacune des trois autres paires de lignées des nouvelles reines de génotype inter-lignée sont produites par une minorité de colonies. Par contre, les colonies avec une reine mère de génotype inter-lignée ne se développent pas suffisamment pour produire des individus reproducteurs. Ceci peut donc expliquer pourquoi il n'y a pas de flux de gènes entre les deux lignées de trois paires. En conclusion, les résultats de cette thèse montrent que la détermination génétique de la caste est coûteuse mais très répandue chez les fourmis. moissonneuses du genre Pogonomyrmex. L'isolement reproductif des lignées entre elles et avec les espèces parentales, ainsi qu'un succès de fondation fréquence-dépendant contribuent à la persistance de ce système extraordinaire.

Growth in a Cross-Section of Cities: Location, Increasing Returns or Random Growth?

This article analyzes empirically the main existing theories on income and population city growth: increasing returns to scale, locational fundamentals and random growth. To do this we implement a threshold nonlinearity test that extends standard linear growth regression models to a dataset on urban, climatological and macroeconomic variables on 1,175 U.S. cities. Our analysis reveals the existence of increasing returns when per-capita income levels are beyond $19; 264. Despite this, income growth is mostly explained by social and locational fundamentals. Population growth also exhibits two distinct equilibria determined by a threshold value of 116,300 inhabitants beyond which city population grows at a higher rate. Income and population growth do not go hand in hand, implying an optimal level of population beyond which income growth stagnates or deteriorates

Nest-box design for the study of diurnal raptors and owls is still an overlooked point in ecological, evolutionary and conservation studies: a review

The use of artificial nest-boxes has led to significant progress in bird conservation and in our understanding of the functional and evolutionary ecology of free-ranging birds that exploit cavities for roosting and reproduction. Nest-boxes and their improved accessibility have made it easier to perform comparative and experimental field investigations. However, concerns about the generality and applicability of scientific studies involving birds breeding in nest-boxes have been raised because the occupants of boxes may differ from conspecifics occupying other nest sites. Here we review the existing evidence demonstrating the importance of nest-box design to individual life-history traits in three falcon (Falconiformes) and seven owl (Strigiformes) species, as well as the extent to which publications on these birds describe the characteristics of exploited artificial nest-boxes in their 'methods' sections. More than 60% of recent publications did not provide any details on nest-box design (e.g. size, shape, material), despite several calls >15 years ago to increase the reporting of such information. We exemplify and discuss how variation in nest-box characteristics can affect or confound conclusions from nest-box studies and conclude that it is of overall importance to present details of nest-box characteristics in scientific publications.

Triatominae as a model of morphological plasticity under ecological pressure

The use of biochemical and genetic characters to explore species or population relationships has been applied to taxonomic questions since the 60s. In responding to the central question of the evolutionary history of Triatominae, i.e. their monophyletic or polyphyletic origin, two important questions arise (i) to what extent is the morphologically-based classification valid for assessing phylogenetic relationships? and (ii) what are the main mechanisms underlying speciation in Triatominae? Phenetic and genetic studies so far developed suggest that speciation in Triatominae may be a rapid process mainly driven by ecological factors.

Estudio del ecosistema urbano de San José. Protocolo de monitoreo de aves y naturalización del Parque La Sabana

El papel de la ciudad en el futuro de la humanidad será transcendente, y es que el crecimiento actual de los espacios urbanos tiende, en general, a desbordar el sitio original de las ciudades, abarcando territorios cada vez más extensos y discontinuos. Y por este motivo es de vital importancia el estudio de la ciudad y de su entorno, el cual es sinónimo de ecosistema urbano. En el siguiente estudio se evalúa el ecosistema urbano de San José, capital de Costa Rica, dando énfasis en las zonas verdes presentes, en las relaciones con los ecosistemas naturales circundantes y como mejorar su capacidad ecológica. Por este motivo se ha analizado un proceso de rearborización en el Parque Metropolitano La Sabana, principal nódulo de carga de la trama urbana. Este esfuerzo de naturación dotará al parque de una mayor naturalización, con lo que se espera un aumento de la biodiversidad faunística. Para conocer estos cambios se crea un programa de monitoreo de aves con su respectivo protocolo.

Etiology of first-ever ischaemic stroke in European young adults: the 15 cities young stroke study.

BACKGROUND AND PURPOSE: Risk factors for IS in young adults differ between genders and evolve with age, but data on the age- and gender-specific differences by stroke etiology are scare. These features were compared based on individual patient data from 15 European stroke centers. METHODS: Stroke etiology was reported in detail for 3331 patients aged 15-49 years with first-ever IS according to Trial of Org in Acute Stroke Treatment (TOAST) criteria: large-artery atherosclerosis (LAA), cardioembolism (CE), small-vessel occlusion (SVO), other determined etiology, or undetermined etiology. CE was categorized into low- and high-risk sources. Other determined group was divided into dissection and other non-dissection causes. Comparisons were done using logistic regression, adjusting for age, gender, and center heterogeneity. RESULTS: Etiology remained undetermined in 39.6%. Other determined etiology was found in 21.6%, CE in 17.3%, SVO in 12.2%, and LAA in 9.3%. Other determined etiology was more common in females and younger patients, with cervical artery dissection being the single most common etiology (12.8%). CE was more common in younger patients. Within CE, the most frequent high-risk sources were atrial fibrillation/flutter (15.1%) and cardiomyopathy (11.5%). LAA, high-risk sources of CE, and SVO were more common in males. LAA and SVO showed an increasing frequency with age. No significant etiologic distribution differences were found amongst southern, central, or northern Europe. CONCLUSIONS: The etiology of IS in young adults has clear gender-specific patterns that change with age. A notable portion of these patients remains without an evident stroke mechanism according to TOAST criteria.