Heterogeneidade ambiental e comunidade de anuros em agroecossistema na região do Pantanal, Brasil

The Pantanal of central Brazil has experienced considerable modifications as a result of growing land use. The association between anuran assemblage and the local habitat structure of an agroecosystem in central Brazil at the Pantanal is described. It is shown that the structure of the anuran community is reestablished within the new environmental dynamics in such human-modified habitat. Twenty-four anuran species were recorded in the area. The community was dominated by four species (Dendropsophus nanus, Leptodactylus chaquensis, Hypsiboas raniceps, and Rhinella cf. bergi), which accounted for more than 50% of the sampled individuals. The species distribution pattern was adjusted to the logarithmic, log-normal, and broken stick models, partially reflecting its association with agroecosystem characteristics. Habitat heterogeneity contributes to the anuran community at a local scale, thereby emphasizing the importance of maintaining distinct habitats for anuran species in the Pantanal as a management practice, even in in situations in which anthropic actions are predictable, as in agroecosystems.A planície pantaneira no Brasil Central tem sofrido intensa modificação devido às práticas de ocupação antrópica ocorrida nos últimos anos na região. Este trabalho ilustra a associação entre a comunidade de anfíbios anuros e a estrutura ambiental em escala local de um agroecossistema no Pantanal (Mato Grosso do Sul) e mostra que em ambientes modificados pela ação humana a comunidade de anuros pode ser restabelecida de acordo com as novas condições encontradas. Foram encontradas 24 espécies de anuros das quais quatro foram predominantes (Dendropsophus nanus, Leptodactylus chaquensis, Hypsiboas raniceps e Rhinella cf. bergi), representando mais de 50% dos indivíduos amostrados. O padrão de distribuição das espécies foi melhor ajustado aos modelos logarítmicos, log-normal e broken stick, refletindo parcialmente uma associação com as características do agroecossistema. A heterogeneidade ambiental contribuiu com a estrutura da comunidade, o que reforça a importância da manutenção de ambientes distintos para as espécies de anuros do Pantanal como uma prática de manejo mesmo em situações em que as ações antrópicas forem previsíveis e irreversíveis como os agroecossistemas

Survival rate and changes in foraging performances of solitary bees exposed to a novel insecticide

Abstract Solitary bees are among the most important pollinators worldwide however population declines especially in croplands has been noticed. The novel pesticide sulfoxaflor is a competitive modulator of nicotinic acetylcholine receptors (nAChR) in insects. While there is evidence of a negative impact of neonicotinoids on bees of several social organization levels, our overall knowledge on the impact of sulfoxaflor on bees is poor. Here we present for the first time a study showing effects of field realistic doses of sulfoxaflor on solitary bees. Bees submitted to long term exposure of field realistic doses of sulfoxaflor (5 µg dm-3, 10 µg dm-3, 50 µg dm-3) and control were observed regarding their survival rate. Moreover, we recorded metrics related to flower visitation and flight performance. We discover that the highest field realistic dose is lethal to Osmia bicornis along five days of exposure. The effect of sulfoxaflor reduces the outcome of foraging, important features for fruit and seed production of cross-pollinated plant species. Bees exposed to pesticide visited flowers mostly walking rather than flying. Flight performance was also impaired by the pesticide

Ant Community in Neotropical Agrosystems: A Four-Year Study in Conventional and No-Tillage Systems

Studies comparing agricultural practices that maintain a better quality and a healthy soil fauna consider the no-tillage farming as the most effective practice when compared to other planting techniques. In order to evaluate the influence of the no-tillage and conventional tillage methods (with and without manipulation of the soil before planting, respectively) on ant communities, we monitored two areas with these two types of practice (conventional and no-tillage) over the period of four years. We collected ants once per month along 10 transects randomly distributed using three pitfall traps in each area. In addition, we collected the dead plant biomass present at each point sampled as a parameter for measuring the environmental complexity of the areas. In total, we captured 27,480 individuals belonging to 26 species in the no-tillage area and 24,570 individuals belonging to 24 species in the conventional tillage area. The generalised linear model analysis showed that the no-tillage system had the highest abundance of individuals, as well as richness and diversity of species, during most of the study period, as compared to conventional tillage areas. We also found a significant positive correlation between species richness and dead plant biomass. Thus, it is possible to infer that the no-tillage area is a more complex environment with a greater diversity of ants and, therefore, a more sustainable agrosystem as compared to conventional tillage areas

Predicting the geographic distribution of Lutzomyia longipalpis (Diptera: Psychodidae) and visceral leishmaniasis in the state of Mato Grosso do Sul, Brazil

To understand the geographic distribution of visceral leishmaniasis (VL) in the state of Mato Grosso do Sul (MS), Brazil, both the climatic niches of Lutzomyia longipalpis and VL cases were analysed. Distributional data were obtained from 55 of the 79 counties of MS between 2003-2012. Ecological niche models (ENM) of Lu. longipalpis and VL cases were produced using the maximum entropy algorithm based on eight climatic variables. Lu. longipalpis showed a wide distribution in MS. The highest climatic suitability for Lu. longipalpis was observed in southern MS. Temperature seasonality and annual mean precipitation were the variables that most influenced these models. Two areas of high climatic suitability for the occurrence of VL cases were predicted: one near Aquidauana and another encompassing several municipalities in the southeast region of MS. As expected, a large overlap between the models for Lu. longipalpis and VL cases was detected. Northern and northwestern areas of MS were suitable for the occurrence of cases, but did not show high climatic suitability for Lu. longipalpis . ENM of vectors and human cases provided a greater understanding of the geographic distribution of VL in MS, which can be applied to the development of future surveillance strategies

Geographic distribution of phlebotomine sandfly species (Diptera: Psychodidae) in Central-West Brazil

This study updates the geographic distributions of phlebotomine species in Central-West Brazil and analyses the climatic factors associated with their occurrence. The data were obtained from the entomology services of the state departments of health in Central-West Brazil, scientific collections and a literature review of articles from 1962-2014. Ecological niche models were produced for sandfly species with more than 20 occurrences using the Maxent algorithm and eight climate variables. In all, 2,803 phlebotomine records for 127 species were analysed. Nyssomyia whitmani,Evandromyia lenti and Lutzomyia longipalpiswere the species with the greatest number of records and were present in all the biomes in Central-West Brazil. The models, which were produced for 34 species, indicated that the Cerrado areas in the central and western regions of Central-West Brazil were climatically more suitable to sandflies. The variables with the greatest influence on the models were the temperature in the coldest months and the temperature seasonality. The results show that phlebotomine species in Central-West Brazil have different geographical distribution patterns and that climate conditions in essentially the entire region favour the occurrence of at least one Leishmania vector species, highlighting the need to maintain or intensify vector control and surveillance strategies

Habitat heterogeneity and anuran community of an agroecosystem in the Pantanal of Brazil

The Pantanal of central Brazil has experienced considerable modifications as a result of growing land use. The association between anuran assemblage and the local habitat structure of an agroecosystem in central Brazil at the Pantanal is described. It is shown that the structure of the anuran community is reestablished within the new environmental dynamics in such human-modified habitat. Twenty-four anuran species were recorded in the area. The community was dominated by four species (Dendropsophus nanus, Leptodactylus chaquensis, Hypsiboas raniceps, and Rhinella cf. bergi), which accounted for more than 50% of the sampled individuals. The species distribution pattern was adjusted to the logarithmic, log-normal, and broken stick models, partially reflecting its association with agroecosystem characteristics. Habitat heterogeneity contributes to the anuran community at a local scale, thereby emphasizing the importance of maintaining distinct habitats for anuran species in the Pantanal as a management practice, even in in situations in which anthropic actions are predictable, as in agroecosystems

Predacious activity of Ants (Hymenoptera: Formicidae) in conventional and in No-till agriculture systems

This study had the objective of assessing the differences in foraging activity of the predacious ants between two areas, one conventional and other with no-till agriculture systems. The research was conducted in two contiguous 1.5 ha plots in Dourados MS, Brazil, from February 2001 to December 2003. Each plot received 750 baits (Nasutitermes termites), 425 at daylight and 325 at night. The termites were placed on the filter paper, on the ground, and ant attack was monitored for 15 min, until removed. Sixteen ant species were found in the no-till system and nine in the conventional system. Baits removed from no-till were significantly higher than the conventional plots and were influenced by the sampling time, at day or night. The seasons of the year did not significantly explain the variations in the structure of the predacious ant communities in neither of the systems. The significant differences at foraging activity and ant richness between the areas indicated that the no-tillage system could improve environmental quality of the cropping and therefore, became an important tool for the integrated pest management programs

Disentangling the path of pollinator attraction in temporarily colored flowers

Plants may use different strategies to attract pollinators in long distance (e.g. floral display) and in short distance (e.g. ratio between differentially colored flowers) scales. The Verbenaceae Lantana canescens Kunth is a wide spread species in open sites of the Brazilian Pantanal wetland. Individuals of this generalist species can produce a variable number of open inflorescences with yellow and white flowers that are organized in whorls. In this study we tested the hypothesis that increased floral display (long distance attraction) and the ratio between yellow and white flowers (short distance attraction) enhances the number of pollinator species and individuals. We observed flower visitors and calculated floral parameters in 38 plots of 1 m2 each, that contained a varying number of flowering L. canescens individuals. Non-metric multidimensional scaling and Bray-Curtis distances were used to account for flower visitor composition and the relative visitation rate, respectively. We used a structural equation model to test the power of each predictor variable on the visitation rate and a covariance analysis to disentangle the effect of each independent variable on the frequency of plant-pollinator interactions. We found that the number of flower visitors and the visitation rate increased with increasing number of inflorescences. Disentangling long and short distance attraction indicated that the number of inflorescences (per plot) and the number of yellow flowers (yellowing effect) contributed most to flower visitation at long and short distance, respectively

Feeding habits and habitat use of three sympatric piranha species in the Pantanal wetland of Brazil

We investigated the diet and habitat use of sympatric piranha species (Serrasalmus maculatus, S. marginatus, Pygocentrus nattereri) in three rivers and three lagoons of the Miranda River basin in the Southern Pantanal, Brazil. The three species showed differences in size, weight, abundance, and diet between sites; but not in terms of habitat use. Serrasalmus maculatus and P. nattereri were most abundant in rivers and lagoons. The low abundance of S. marginatus could be due to its solitary and territorial behavior. Stomach content analysis of S. maculatus and P. nattereri revealed that vegetal material was the main food item consumed. As for S. marginatus, fish fins and scales were the most frequent food item, a direct consequence of its specialized feeding habit. Differences in diet composition amongst the three sympatric piranha species suggest that competition for food resources does not play an important role in the trophic interactions of these species in the Pantanal. © 2007 by Verlag Dr. Friedrich Pfeil