The antennal sensilla of Melipona quadrifasciata (Hymenoptera: Apidae: Meliponini): a study of different sexes and castes

The sensilla of insects are integumental units that play a role as sensory structures and are crucial for the perception of stimuli and for communication. In this study, we compared the antennal sensilla of females (workers and queens), males (haploid (n) and diploid (2n)), and queen-like males (QLMs, resulting from 2n males after juvenile hormone (JH) treatment) in the stingless bee Melipona quadrifasciata. Images of the dorsal antenna surfaces were acquired using a scanning electron microscope. As reported for other hymenopterans, this species exhibits a heterogeneous sensillar distribution along the antennae. Thirteen different types of sensilla were found in the antennae of M. quadrifasciata: trichodea (subtypes I to VI), chaetica (subtypes I and II), placodea, basiconica, ampullacea, coeloconica, and coelocapitula. Sensilla trichodea I were the most abundant, followed by sensilla placodea, which might function in olfactory perception. Sensilla basiconica, sensilla chaetica I, sensilla coeloconica, and sensilla ampullacea were found exclusively in females. In terms of the composition and size of the sensilla, the antennae of QLMs most closely resemble those of the 2n male, although QLMs exhibit a queen phenotype. This study represents the first comparative analysis of the antennal sensilla of M. quadrifasciata. The differences found in the type and amount of sensilla between the castes and sexes are discussed based on the presumed sensillary functions.     

Will Simplified Modalities and Procedures Make More Small-Scale Forestry Projects Viable Under the Clean Development Mechanism?

Simplified modalities and procedures (M&P) are expected to increase the viability of small-scale project activities under the Clean Development Mechanism (CDM). A small-scale afforestation or reforestation (AR) project is defined as a project removing less than 8 kilotons of carbon dioxide equivalent (CO₂e) per year. Depending on the project type and the method for measuring scale, 8 kilotons of CO₂e per year correspond to highly diverse areas, possibly ranging from 200 to 6000 ha. Using a model to calculate the minimum project scale above which the CDM is a positive financial incentive for eligible AR project activities, the paper analyzes whether a reduction of transaction costs under simplified M&P will be a sufficient incentive to motivate small-scale participation in the CDM. Model results show that, even under optimistic assumptions on carbon market conditions and transaction costs, small-scale project activities will not benefit from simplified M&P. Results also show that project activities removing more than 8 kilotons of CO₂e per year and registered as small-scale would be the ones that could benefit the most from simplified M&P. It is concluded that the participation of small-scale project activities to the CDM requires more than simplified M&P, the price of expiring Certified Emission Reductions being one of the most critical parameters.     

A new photoproduct of the drug furosemide in aqueous media

The solar phototransformation of furosemide has been investigated in aqueous media. Irradiation of the drug in distilled water, in water and humic acids or nitrate ions, and in sewage sludge water affords a new dehalogenated dimer. The formation of the dimer has been explained by the formation of a cation radical intermediate. The low-measured environmental concentration of furosemide with respect to predicted environmental concentration in the Po and Lambro Rivers could be justified by its phototransformation.     

Finding threatened forest areas in the central volcanic mountain range conservation area in Costa Rica

The degree at which tropical forests are exposed to human pressure is spatially dependent. Population density, proximity to roads, terrain slope, logging activities and land distribution projects are well known factors inducing deforestation and forest degradation in Latin America. Using expert knowledge to weight these threat factors and a Geographical Information System for spatial modeling, a multi-criteria analysis procedure is presented, that allows stratifying a study region in categories of deforestation threat. The procedure was implemented in the Central Volcanic Mountain Range Conservation Area (CVMRCA) in Costa Rica with the purpose of finding areas with a combination of physical and socioeconomic characteristics that is particularly predisposing to a high probability of deforestation. To validate the map, the CVMRCA was stratified in categories of deforestation risk, and the result was superposed to historical deforestation data of the period 1986–1996. The good correlation between risk category and historical deforestation (r = 0.91, p < 0.001) indicates that the map can be used as a decision support tool for defining priority areas for conservation action.     

Molecular evidence for benzo[a]pyrene and naphthalene genotoxicity in Trifolium repens L

Polycyclic aromatic hydrocarbons (PAHs) are among the most dangerous environmental contaminants due to their toxic, carcinogenic and mutagenic effects. Although there are many data in literature that detail the effects of PAHs on animals, little is known about their action on higher plants which are often used as bioindicators. The aim of the present study was to evaluate the genotoxicity of two different PAHs, benzo[a]pyrene (BaP) and naphthalene (Naph), on Trifolium repens L. Clover plants were exposed to soil which had been artificially contaminated with three concentrations of BaP (5, 10 and 20 microg g-1) or Naph (25, 50 and 100 microg g-1). After 15 days, changes in the DNA content and sequence of roots and shoots were evaluated by flow cytometry (FCM) and amplified fragment length polymorphism (AFLP). Root and shoot dry weight were also determined to assess plant growth. Results showed that BaP and Naph were both genotoxic for white clover, inducing significant changes in root and shoot DNA sequence. Damage was more severe in the root than in the shoot suggesting that the translocation of these compounds and their genotoxic metabolites was limited. Ploidy alterations were not detected and the extent of damage caused by all the tested PAH concentrations was not sufficient to affect plant development.     

Toxicity of prednisolone, dexamethasone and their photochemical derivatives on aquatic organisms

Light exposure of aqueous suspensions of prednisolone and dexamethasone causes their partial phototransformation. The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means. Prednisolone, dexamethasone and their photoproducts have been tested to evaluate their acute and chronic toxic effects on some freshwater chain organisms. The rotifer Brachionus calyciflorus and the crustaceans Thamnocephalus platyurus and Daphnia magna were chosen to perform acute toxicity tests, while the alga Pseudokircheneriella subcapitata (formerly known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia to perform chronic tests. The photochemical derivatives are more toxic than the parent compounds. Generally low acute toxicity was found. Chronic exposure to this class of pharmaceuticals caused inhibition of growth population on the freshwater crustacean C. dubia while the alga P. subcapitata seems to be less affected by the presence of these drugs.     

A SEMI-DISTRIBUTED ADAPTIVE MODEL FOR REAL-TIME FLOOD FORECASTING1

ABSTRACT: A semi-distributed deterministic model for real-time flood forecasting in large basins is proposed. Variability of rainfall and losses in space is preserved and the effective rainfall-direct runoff model segment based on the Clark procedure is incorporated. The distribution of losses in space is assumed proportional to rainfall intensity and their evolution in time is represented by the φ-index; furthermore, an initial period without production of effective rainfall is considered. The first estimation of losses and the associated forecasts of flow are performed at the time corresponding to the first rise observed in the hydrograph. Then the forecasts of flow are corrected at each subsequent time step through the updating of the φ-index. The model was tested by using rainfall-runoff events observed on two Italian basins and the predictions of flow for lead times up to six hours agree reasonably well with the observations in each event. For example, for the coefficient of persistence, which compares the model forecasts with those generated by the no-model assumption, appreciable positive values were computed. In particular, for the larger basin with an area of 4,147 km², the mean values were 0.4, 0.4 and 0.5 for forecast lead times of two hours, four hours and six hours, respectively. Good performance of the model is also shown by a comparison of its flow predictions with those derived from a unit hydrograph based model     

Using Vegetation Analysis to Facilitate the Selection of Conservation Sites in Eastern Paraguay

This study demonstrates the use of vegetation analysis in the selection of priority areas for conservation. The analysis is based on field data derived from narrow rectangular sample plots and includes information from the database of Paraguay's Conservation Data Center. Ten 100-m² sample plots were laid out for each survey site. We compared three sites, Mbaracayú, Tarumá, and Parabel, all forests located in the ecoregion of Selva Central in eastern Paraguay. Subtropical and physiognomically similar, the sites are dominated by a single species, either Sorocea bonplandii or Actinostemon concolor , but differ in species richness. Vegetation analysis permitted us to calculate the total number of species, including liana species, the number of economic plants, and the number of rare, uncommon, and vulnerable species, and thus to quantify the conservation worthiness of the candidate sites. Our study pinpoints Mbaracayú as a mature, resource-rich forest with the highest habitat and plant species diversity and several local endemics. We maintain that it is the area of Paraguay's Selva Central most important for conservation.