Reproduction of the Freshwater Catfish Pimelodella pappenheimi in Southern Brazil

In the subtropical Atlantic rain forest of southern Brazil, reproduction of the catfish Pimelodella pappenheimi was studied over a two years period in a small coastal stream representing a widely undisturbed aquatic habitat. According to analyses of the gonad status, reproduction is mainly seasonal with a peak in the rainy summer months, consisting of multiple spawning. The average body length of the fishes attaining sexual maturity was the same in both sexes. At the study site summer storms cause flash floods, and heavy rainfalls can suddenly increase the river flow. Reproductive females were found to burrow in the clay palisades of the river sediments which is regarded a behavioural adaptation protecting the offspring from being washed away.     

The recolonization of the Krakatau islands by termites (Isoptera), and their biogeographical origins

The termite assemblages of the Krakatau islands and five sites in Sumatra and Java were investigated, using a standardized transect sampling method. Five species were found on the Krakatau islands that have not been collected there before. The total number of termites recorded on the islands since the 1883 volcanic eruption is now twelve species, all of which are wood feeders. No termites nesting in or feeding on the soil were found on the Krakataus, suggesting that rafting in wood is the primary method by which the termites recolonized the islands.     

Environment versus dispersal in the assembly of western Amazonian palm communities

Aim It is a central issue in ecology and biogeography to understand what governs community assembly and the maintenance of biodiversity in tropical rain forest ecosystems. A key question is the relative importance of environmental species sorting (niche assembly) and dispersal limitation (dispersal assembly), which we investigate using a large dataset from diverse palm communities. Location Lowland rain forest, western Amazon River Basin, Peru. Methods We inventoried palm communities, registering all palm individuals and recording environmental conditions in 149 transects of 5 m × 500 m. We used ordination, Mantel tests and indicator species analysis (ISA) to assess compositional patterns, species responses to geographical location and environmental factors. Mantel tests were used to assess the relative importance of geographical distance (as a proxy for dispersal limitation) and environmental differences as possible drivers of dissimilarity in palm species composition. We repeated the Mantel tests for subsets of species that differ in traits of likely importance for habitat specialization and dispersal (height and range size). Results We found a strong relationship between compositional dissimilarity and environmental distance and a weaker but also significant relationship between compositional dissimilarity and geographical distance. Consistent with expectations, relationships with environmental and geographical distance were stronger for understorey species than for canopy species. Geographical distance had a higher correlation with compositional dissimilarity for small‐ranged species compared with large‐ranged species, whereas the opposite was true for environmental distance. The main environmental correlates were inundation and soil nutrient levels. Main conclusions The assembly of palm communities in the western Amazon appears to be driven primarily by species sorting according to hydrology and soil, but with dispersal limitation also playing an important role. The importance of environmental characteristics and geographical distance varies depending on plant height and geographical range size in agreement with functional predictions, increasing our confidence in the inferred assembly mechanisms.     

Effect of organic and conventional farming on soil bacterial diversity of pecan tree (Carya illinoensis K. Kosh) orchard across two phenological stages

We described the bacterial diversity of walnut grove soils under organic and conventional farming. The bacterial communities of rhizospheric and nonrhizospheric soils of pecan tree (Carya illinoensis K. Koch) were compared considering two phenological stages (sprouting and ripening). Sixteen operational taxonomic units (OTUs) were identified significantly more abundant according to the plant development, only one according to the farming condition, and none according to the soil origin. The OTUs specificaly abundant according to plant development included Actinobateria (2) and Betaproteobacteria (1) related OTUs more abundant at the sprouting stage, while at the fruit ripening (FR) stage the more abundant OTUs were related to Actinobacteria (6), Alphaproteobacteria (6), and unclassified Bacteria (1). The Gaiellaceae OTU18 (Actinobacteria) was more abundant under conventional farming. Thus, our study revealed that the plant development stage was the main factor shaping the bacterial community structure, while less influence was noticed for the farming condition. The bacterial communities exhibited specific metabolic capacities, a large range of carbon sources being used at the FR stage. The identified OTUs specifically more abundant represent indicators providing useful information on soil condition, potential tools for the management of soil bacterial communities.     

Integrated management of fusarial wilt of tomato with implementation of soil solarisation

Fusarial wilt of tomato (Lycopersicon esculentum Mill.) is a very common and severe disease occurring in most of the vegetable fields in West Bengal, India. Potenciation and formulation of different fungicidal chemicals and phytoextracts were evaluated against the growth of the pathogen wherein carbendazim (bavistin) and leaf extracts of Azadirachta indica (neem) were recorded to be most effective. Combined treatment with 4 ml neem leaf extract and 1 ml captan (0.01%) or with 4 ml garlic bulb extract and 1 ml captan (0.01%) exhibited 100% growth inhibition of the pathogen. Integrated control of the pathogen with phytoextracts, fungicide and biocontrol agents was carried out. Among the treatments, a combination with extracts of neem, captan (0.01%) and metabolites of Trichoderma harzianum was proved to be superior over the other. Field experiment with three fungicides at 0.5% concentration was carried out in randomised block design where application of bavistin showed up to 62.27% reduction of wilt infection in tomato plants. Soil solarisation of tomato field showed 62.50 and 66.69% reduction of infection during the trial years. However, integration of soil solarisation with the applications of T. harzianum, captan (0.01%) and neem resulted in 100% reduction of infection and thus it was recorded as the most effective treatment in reducing the incidence of the disease.