Monogamy in large bee societies: a stingless paradox

High genetic diversity is important for the functioning of large insect societies. Across the social Hymenoptera (ants, bees, and wasps), species with the largest colonies tend to have a high colony-level genetic diversity resulting from multiple queens (polygyny) or queens that mate with multiple males (polyandry). Here we studied the genetic structure of Trigona spinipes, a stingless bee species with colonies an order of magnitude larger than those of polyandrous honeybees. Genotypes of adult workers and pupae from 43 nests distributed across three Brazilian biomes showed that T. spinipes colonies are usually headed by one singly mated queen. Apart from revealing a notable exception from the general incidence of high genetic diversity in large insect societies, our results reinforce previous findings suggesting the absence of polyandry in stingless bees and provide evidence against the sperm limitation hypothesis for the evolution of polyandry. Stingless bee species with large colonies, such as T. spinipes, thus seem promising study models to unravel alternative mechanisms to increase genetic diversity within colonies or understand the adaptive value of low genetic diversity in large insect societies.     

Post-merger time series analysis: Iron ore mining

In Brazil, mergers and acquisitions are usually analyzed by the antitrust authorities ex post, following a Structure-Conduct-Performance approach close to the US Merger Guidelines. However, this framework was unable to address the complexity posed by a series of acquisitions of four mining companies by the newly privatized national champion Companhia Vale do Rio Doce (known then as CVRD, nowadays as Vale). This article extends a Vector Error Correction model estimated by the Brazilian Ministry of Justice, which eventually came to reinforce the definition of the relevant geographic market and to test for structural breaks in the price series. A formal horizontal merger simulation model was not viable from the available data. Though international prices Granger-caused domestic prices in Brazil, they explain less than a third of the variance. Domestic price hikes in the acquired miners’ series were observed above the export price increase not long after the acquisitions, and a structural break could not be rejected. Since convergence of domestic prices to international levels were not to be punished, remedies eventually applied by the Brazilian Antitrust Tribunal focused on preventing CVRD from abusing dominant position to vertically foreclose competitors in logistics, a key competitive issue for the industry.     

Polycyclic aromatic hydrocarbons and their oxygenated derivatives in urban aerosol: levels,chemical profiles,and contribution to PM2.5 oxidative potential

Environmental Science and Pollution Research - The concentrations of polycyclic aromatic hydrocarbons (PAHs) and quinones, a subgroup of oxygenated PAHs (oxy-PAHs), were measured in PM2.5 samples...     

Emergy and emergy algebra explained by means of ingenuous set theory

Emergy is an important concept that has originated several effects in ecology, systems ecology and sustainability science. Its communication, however, has always presented several problems, since it does not follow the same rules of conservation as other energy-based approaches. Attempts have been made to clarify emergy by means of more formal/mathematical approaches, but the problem persists. In this paper, we have introduced a view of emergy and of its algebra based on ingenuous set theory. By means of this simple tool, emergy can be defined as the set of solar exergy that is directly and indirectly necessary to make a product. The operation that correctly sums the emergy “carried” by the inputs to a process is the union. This definition and the operation of union are able to account for all the rules of emergy algebra.     

Understanding fungal potential in the mitigation of contaminated areas in the Czech Republic: tolerance,biotransformation of hexachlorocyclohexane (HCH) and oxidative stress analysis

Environmental Science and Pollution Research - The study of the soil microbial community represents an important step in better understanding the environmental context. Therefore, biological...     

Saprotrophic soil fungi to improve phosphorus solubilisation and release: In vitro abilities of several species

Modern agriculture is dependent on phosphate rock (PR), which is a nonrenewable resource. Improvement of phosphorus (P) availability for crops in agricultural soils represents a key strategy to slow down the depletion of PR. The aim of this study was to identify potential P biofertilisers among saprotrophic fungal species. We tested 30 fungal strains belonging to 28 taxa (4 Zygomycota and 24 Ascomycota) and with different life strategies. The study showed that many saprotrophic fungi have the ability to mobilise P from insoluble forms according to a variety of mechanisms. Our results expand the pool of P solubilising fungal species, also suggesting a new solubilisation index and shedding light on parameters that could be basic in the selection of efficient soil P-biofertilisers fungi. Rhizopus stolonifer var. stolonifer, Aspergillus niger and Alternaria alternata were found to be the best performing strains in terms of amounts of TCP solubilisation.     

Anaerobic digestion of microalgal biomass after ultrasound pretreatment

High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16–67 MJ/kg TS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16–100%), hydrolysis rate (25–56%) and methane yield (6–33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS).     

Chelate-induced phytoextraction of metal polluted soils with Brachiaria decumbens

Chelate-induced phytoextraction with high biomass plant species has been proposed for the clean-up of heavy metal polluted soils. In the current work, the effect of the application of two different chelating agents, i.e. EDTA and EDDS, on the metal phytoextraction capacity of Brachiaria decumbens was studied. Although EDTA was, in general, more effective in soil metal solubilization, EDDS, a chelate less harmful to the environment, was more efficient inducing metal accumulation in B. decumbens shoots than EDTA. Indeed, in a moderately heavy metal polluted soil, EDDS caused a 2.54, 2.74 and 4.30-fold increase in Cd, Zn, and Pb shoot metal concentration, respectively, as compared to control plants. In this same soil, EDTA caused a 1.77, 1.11 and 1.87-fold increase in Cd, Zn, and Pb shoot metal concentration, respectively, as compared to control plants. EDDS was also more effective than EDTA in stimulating the translocation of metals from roots to shoots. B. decumbens plants were able to grow in the metal polluted soils showing no visible symptoms of phytotoxicity, which suggests their metal tolerance. Finally, B. decumbens, a fast-growing, high biomass, aluminum tolerant plant species, that has a well-established agronomic system, fulfills most of the requirements for chemically-induced phytoextraction.     

Urban air pollution monitoring and correlation properties between fixed-site stations

The rich regional air-monitoring network of the Emilia-Romagna region of Italy has been used to quantify the spatial variability of the main pollutants within urban environments and to analyze the correlations between stations. The spatial variability of the concentrations of the majority of pollutants within the city was very high, making it difficult to differentiate and characterize the urban environments and to apply legal limits with uniform criteria. On the other hand, the correlations between the fixed-site monitoring stations were high enough for their data to be retained generally very appropriately for controlling temporal trends. Starting from the high correlation level, a procedure was proposed and tested to derive pollution levels, using short-term measurements, such as passive samplers and mobile-station data. The importance of long-term statistics in urban air pollution mapping was emphasized. Treatment of missing data in time series and quality assurance were indicated as possible fields for applications for the correlation properties.