Coming of age in an ant colony: cephalic muscle maturation accompanies behavioral development in <Emphasis Type="Italic">Pheidole dentata</Emphasis>

Although several neurobiological and genetic correlates of aging and behavioral development have been identified in social insect workers, little is known about how other age-related physiological processes, such as muscle maturation, contribute to task performance. We examined post-eclosion growth of three major muscles of the head capsule in major and minor workers of the ant Pheidole dentata using workers of different ages with distinct task repertoires. Mandible closer muscle fibers, which provide bite force and are thus critical for the use of the mandibles for biting and load carrying, fill the posterio-lateral portions of the head capsule in mature, older workers of both subcastes. Mandible closer fibers of newly eclosed workers, in contrast, are significantly thinner in both subcastes and grow during at least the next 6 days in minor workers, suggesting this muscle has reduced functionality for a substantial period of adult life and thus constrains task performance capability. Fibers of the antennal muscles and the pharynx dilator, which control antennal movements and food intake, respectively, also increase significantly in thickness with age. However, these fibers are only slightly thinner in newly eclosed workers and attain their maximum thickness over a shorter time span in minors. The different growth rates of these functionally distinct muscles likely have consequences for how adult P. dentata workers, particularly minors, develop their full and diverse task repertoire as they age. Workers may be capable of feeding and interacting socially soon after eclosion, but require a longer period of development to effectively use their mandibles, which enable the efficient performance of tasks ranging from nursing to foraging and defense.     

Analysis of the genotoxic potential of low concentrations of Malathion on the Allium cepa cells and rat hepatoma tissue culture

Based on the concentration of Malathion used in the field, we evaluated the genotoxic potential of low concentrations of this insecticide on meristematic and F₁ cells of Allium cepa and on rat hepatoma tissue culture (HTC cells). In the A. cepa, chromosomal aberrations (CAs), micronuclei (MN), and mitotic index (MI) were evaluated by exposing the cells at 1.5, 0.75, 0.37, and 0.18 mg/mL of Malathion for 24 and 48 hr of exposure and 48 hr of recovery time. The results showed that all concentrations were genotoxic to A. cepa cells. However, the analysis of the MI has showed non-relevant effects. Chromosomal bridges were the CA more frequently induced, indicating the clastogenic action of Malathion. After the recovery period, the higher concentrations continued to induce genotoxic effects, unlike the observed for the lowest concentrations tested. In HTC cells, the genotoxicity of Malathion was evaluated by the MN test and the comet assay by exposing the cells at 0.09, 0.009, and 0.0009 mg/5 mL culture medium, for 24 hr of exposure. In the comet assay, all the concentrations induced genotoxicity in the HTC cells. In the MN test, no significant induction of MN was observed. The genotoxicity induced by the low concentrations of Malathion presented in this work highlights the importance of studying the effects of low concentrations of this pesticide and demonstrates the efficiency of these two test systems for the detection of genetic damage promoted by Malathion.     

Soil,water and plants contamination by total chrome and chrome VI

The chrome (Cr) is a metal utilized in various industrial sectors and its investigation in the environment is necessary, for the Cr (III) contain aessential micronutrients in the human nourishment and the Cr (VI), on the other hand, is toxic. In the present work soil contamination with Cr was realized in drainagelysimetersset in concentrations of 0, 200, 400, 600, 800 and 1000 mg kg⁻¹ of total Cr, with the intuition to determine the total Cr and Cr (VI) flux in leached water, in soil and in plants of lettuce (Lactuca sativa L.). In the lysimeters were cultivated four plants, in three cultivation circles. In the end of the cultivations was observed, that the total applied Cr leached in the soil, evidencing the Cr mobility in latossoil with simulant characteristics to the ones utilized in this paper. The Cr (VI) concentrations in the soil increased soon after the treatment applications, but tend to decrees in the time elapse, the same tendences were observed for the total Cr concentrations in the leached water. The Cr absorption by plants was related to the Cr disponibility in the soil, for the soil concentration and the plants decreased with time passing. The Cr mobility in the soil possibilitated the groundwater contamination presenting risks to the water quality and, consequently to public health.     

Microplastics in seawater: sampling strategies,laboratory methodologies,and identification techniques applied to port environment

Environmental Science and Pollution Research - The European Interreg Italy–France 2014–2020 Maritime Project SPlasH! (Stop to Plastics in H2O!) focused on the study of microplastics...     

Phytoplankton can bypass nutrient reductions in eutrophic coastal water bodies

The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities.     

Toxicity evaluation of cypermethrin,glyphosate, and malathion,on two indigenous zooplanktonic species

In Aguascalientes, Mexico, there is a special concern about pesticides because of their intensive use on guava production areas, which are located in the vicinity of water reservoirs; thus, non-target organisms could be exposed. Thereafter, the aim of this work was to assess the effect of cypermethrin, Faena® (glyphosate), and malathion, which are the most used pesticides in Aguascalientes’ guava production, on the indigenous freshwater species Alona guttata (cladoceran) and Lecane papuana (rotifer). Acute 48-h toxicity tests were carried out, and LC₅₀ values were calculated. Then, five sublethal concentrations (1/80, 1/40, 1/20, 1/10, and 1/5 of the respective LC₅₀) were selected for the chronic assays: (a) intrinsic growth rate analysis in the rotifer and (b) partial life table analysis in the cladoceran. The results of the acute toxicity tests showed that A. guttata was more sensitive to malathion (LC₅₀ = 5.26 × 10^?3 mg/L) at concentrations found in natural environments with continuous application on guava fields, whereas L. papuana was more sensitive to Faena® (LC₅₀ = 19.89 mg/L). The somatic growth of A. guttata was inhibited for the chronic exposure to cypermethrin. In addition, cypermethrin and Faena® seemed to exert endocrine disruptive effects on A. guttata. Moreover, malathion chronic exposure significantly decreased the survival of A. guttata. Moreover, L. papuana was affected chronically for the three pesticides.     

Effects of organic fertilizers on soil physicochemistry and on the yield and botanical composition of forage over 3 years

Organic wastes have been reported to reduce saturation of the exchange complex by Al in Al-rich acid soils. For 3 years, the main soil fertility properties were studied in plots sown with mixed pasture species. These plots were fertilized with cattle slurry, dairy sludge (DS), or granulated broiler litter (BL) in comparison with mineral fertilizer. Al saturation levels were low after the initial inorganic liming treatment (19.00-33.71%) but tended to rise under all treatments (21.09-61.37%) except BL (8.45-30.98%), which was also associated with the highest average soil pH and the highest average levels of exchangeable Ca2+, Mg2+, and K+. Treatment DS performed similarly to mineral fertilizer in most respects, but it led to greater available P levels. Under the dry conditions of the second and third years of the study, BL and DS treatments were associated with significantly greater forage yields than the other treatments. Under DS treatment, available P levels were too low to allow the maintenance of mixed pasture, clover being eliminated by the less P-dependent species.     

Interregional comparison of karst disturbance: West-central Florida and southeast Italy

The karst disturbance index (KDI) consists of 31 environmental indicators contained within the five broad categories: geomorphology, hydrology, atmosphere, biota, and cultural. The purpose of this research is to apply the KDI to two distinct karst areas, west Florida, USA, and Apulia, Italy. Through its application, the utility of the index can be validated and other important comparisons can be made, such as differences in the karst legislations implemented in each region and the effect of time exposure to human occupation to each karst terrain. Humans have intensively impacted the karst of southeast Italy for thousands of years compared to only decades in west-central Florida. However, west-central Florida's higher population density allows the region to reach disturbance levels comparable to those reached over a longer period in Apulia. Similarly, Italian karst is more diverse than the karst found in west-central Florida, creating an opportunity to test all the KDI indicators. Overall, major disturbances for southeast Italy karst include quarrying, stone clearing, and the dumping of refuse into caves, while west-central Florida suffers most from the infilling of sinkholes, soil compaction, changes in the water table, and vegetation removal. The application of the KDI allows a benchmark of disturbance to be established and later revisited to determine the changing state of human impact for a region. The highlighting of certain indicators that recorded high levels of disturbance also allows regional planners to allocate resources in a more refined manner.     

The valuation of historical sites: a case study of Valdivia,Chile

The economic valuation of cultural heritage is an area of increasing interest and an important research topic in the emerging field of cultural economics. Many services and values associated with cultural heritage are not traded in markets, and their estimation requires methods developed for the valuation of non-market goods, such as those used in environmental economics. This paper applies the contingent valuation method with double dichotomous choice to estimate the value of historical sites in the city of Valdivia, Chile. The valuation exercise was implemented by designing a hypothetical guided walking tour to a cluster of historical sites in the city centre, and surveying tourists visiting the city during the summer of 2004. Parametric and non-parametric statistical methods were used to estimate the survival distribution and the mean and median estimates of the willingness-to-pay (WTP). The study emphasizes the importance of explicitly treating heterogeneous preferences and the sensitivity of the survival distribution to the estimation methods used.