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.     

Testing the influence of gravity on flower symmetry in five <Emphasis Type="Italic">Saxifraga</Emphasis> species

Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species—Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa—concerning six flower parameters—angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.     

Effects of three pesticides on the avoidance behavior of earthworms in laboratory tests performed under temperate and tropical conditions

Little research has been performed on the impact of pesticides on earthworms under tropical conditions. Taking into consideration the often-limited resources in tropical countries, simple screening tests are needed. Therefore, it was investigated whether three pesticides relevant for the Brazilian Amazon (benomyl, carbendazim, lambda-cyhalothrin) affect the avoidance behavior of the earthworm Eisenia fetida. The tests were performed for two days according to ISO guideline 17512 but were adapted to tropical conditions (i.e. test substrate, test organism and temperature). The results indicate that this test gives reproducible and reliable results. Toxicity values (NOEC, EC50) are lower than those determined in 14 day-acute mortality tests and are approximately in the same range such as those found in 56 day-chronic reproduction tests with the same earthworm species, which were performed in parallel. Therefore, the use of the earthworm avoidance tests is recommended as a screening tool for the risk assessment of pesticides.     

Influence of tidal regime on the distribution of trace metals in a contaminated tidal freshwater marsh soil colonized with common reed (Phragmites australis)

A historical input of trace metals into tidal marshes fringing the river Scheldt may be a cause for concern. Nevertheless, the specific physicochemical form, rather than the total concentration, determines the ecotoxicological risk of metals in the soil. In this study the effect of tidal regime on the distribution of trace metals in different compartments of the soil was investigated. As, Cd, Cu and Zn concentrations in sediment, pore water and in roots were determined along a depth profile. Total sediment metal concentrations were similar at different sites, reflecting pollution history. Pore water metal concentrations were generally higher under less flooded conditions (mean is (2.32 ± 0.08) × 10⁻³ mg Cd L⁻¹ and (1.53 ± 0.03) × 10⁻³ mg Cd L⁻¹). Metal concentrations associated with roots (mean is 202.47 ± 2.83 mg Cd kg⁻¹ and 69.39 ± 0.99 mg Cd kg⁻¹) were up to 10 times higher than sediment (mean is 20.48 ± 0.19 mg Cd kg⁻¹ and 20.42 ± 0.21 mg Cd kg⁻¹) metal concentrations and higher under dryer conditions. Despite high metal concentrations associated with roots, the major part of the metals in the marsh soil is still associated with the sediment as the overall biomass of roots is small compared to the sediment.     

Effect of herbicides on glutathione S-transferases in the earthworm, <Emphasis Type="Italic">Eisenia fetida</Emphasis>

AIM AND BACKGROUND: Earthworms have been studied as a readily available, easily maintainable and cheap test species for assessing chemical pollution, and may be an alternative to in vivo rodent bioassays. The current investigation aims to characterize detoxification enzymes in Eisenia fetida and stress response against two herbicides with different modes of action, namely, fenoxaprop and metolachlor. METHODS: Herbicides were applied to soil containing earthworms. Animals were then collected, sacrificed and shock-frozen. Extracted protein was analyzed for glutathione S-transferase (GST) activity using CDNB (1-chloro-2,4-dinitrobenzene), DCNB (1,2-dichloro-4-nitrobenzene), pNBC (p-nitrobenzylchloride), PNOBC (p-nitrobenz-o-ylchloride) and selected herbicides. GST isoenzymes were partially purified by affinity chromatography and molecular weights were estimated by SDS-PAGE. RESULTS: In E. fetida protein extracts, GST activity towards model compounds ranked as CDNB>DCNB>PNBOC>PNBC. Fluorodifen was not conjugated at all, but fenoxaprop and metolachlor were conjugated at low rates. Furthermore, the GST isoenzyme pattern changed during the incubation with herbicides, either due to stress or as a defense reaction. After incubation with monochlorobimane, a strong fluorescence of the intestinal tract and the intersegments was observed, indicating organ-specific GST induction. DISCUSSION: According to the author's knowledge, here, for the first time, evidence is presented that E. fetida GST are also capable of conjugating a wider range of xenobiotic substrates. Different forms of GST were observed and changes in GST isoforms due to the herbicide treatment were also noticed. GST conjugation rates varied between different herbicides used in this experiment. It might be assumed that herbicides may well be detoxified by earthworms, to a certain extent, but that they are also potent stress factors influencing the detoxification system of the animal. High doses or long exposure might lead to deleterious effects on earthworms and limit their survival rate. The use of the animals as bioindicators for herbicides and herbicide residues seems very promising, but is surely influenced by the lack of detoxification for some compounds. CONCLUSIONS: Conjugation of several xenobiotics with model substances and herbicides is proven in the earthworm E. fetida. However, E. fetida has only limited capabilities of detoxifying herbicidal compounds. Different isoforms of GST were involved and altered in their activity after treatment. RECOMMENDATIONS AND PERSPECTIVES: The accumulation of GS-conjugates and their determination via fluorescence microscopy is a quick and secure, additional marker for exposure that should be further developed to complement existing biotests. The described methods and endpoints might help to understand the complex reaction of earthworms towards herbicides and lead to an adapted test methodology.     

Detection and identification of baculovirus pesticides by multitemperature single-strand conformational polymorphism

The method of single-strand conformational polymorphism (SSCP) was modified in our laboratories for the characterization of baculoviruses, insect viruses with great potential for use as bioinsecticides in biological protection programs. A series of primers were synthesized after the comparison of the polyhedrin gene sequences of over 20 baculoviruses. Polyhedrin is a highly conserved protein which is responsible for the persistence of the virus in the environment. Universal primers were designed which could be used in polymerase chain reactions (PCR) containing genomic DNA from an array of nucleopolyhedrosis viruses (NPVs) including these which are used as biopesticides against important pests of forests and crops, such as Anticarsia gemmatalis, Spodoptera frugiperda, Lymantria dispar, Lymantria monacha and many others. PCR products were denatured and subjected to single-strand DNA electrophoresis at variable temperatures (MSSCP) where, after silver staining, they gave ssDNA band patterns characteristic for each baculovirus species. This technique can be potentially applied to detect baculoviruses in insects collected in the field, as well as to plant tissues and the excrements or bodies of predators without need for sequencing the PCR products. Sometimes MSSCP can be used not only for species determination but also as an indication of genomic variability which can be related to infectivity.     

Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation, sorption, mineralization and leaching in different soil horizons

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28 km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2 m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1 μg/l in all tested profiles while metribuzine always exceeded the 0.1 μg/l threshold value.     

Bioenergy to save the world

BACKGROUND AND AIM: Following to the 2006 climate summit, the European Union formally set the goal of limiting global warming to 2 degrees Celsius. But even today, climate change is already affecting people and ecosystems. Examples are melting glaciers and polar ice, reports about thawing permafrost areas, dying coral reefs, rising sea levels, changing ecosystems and fatal heat periods. Within the last 150 years, CO2 levels rose from 280 ppm to currently over 400 ppm. If we continue on our present course, CO2 equivalent levels could approach 600 ppm by 2035. However, if CO2 levels are not stabilized at the 450-550 ppm level, the consequences could be quite severe. Hence, if we do not act now, the opportunity to stabilise at even 550 ppm is likely to slip away. Long-term stabilisation will require that CO2 emissions ultimately be reduced to more than 80% below current levels. This will require major changes in how we operate. RESULTS: Reducing greenhouse gases from burning fossil fuels seems to be the most promising approach to counterbalance the dramatic climate changes we would face in the near future. It is clear since the Kyoto protocol that the availability of fossil carbon resources will not match our future requirements. Furthermore, the distribution of fossil carbon sources around the globe makes them an even less reliable source in the future. We propose to screen crop and non-crop species for high biomass production and good survival on marginal soils as well as to produce mutants from the same species by chemical mutagenesis or related methods. These plants, when grown in adequate crop rotation, will provide local farming communities with biomass for the fermentation in decentralized biogas reactors, and the resulting nitrogen rich manure can be distributed on the fields to improve the soil. DISCUSSION: Such an approach will open new economic perspectives to small farmers, and provide a clever way to self sufficient and sustainable rural development. Together with the present economic reality, where energy and raw material prices have drastically increased over the last decade, they necessitate the development and the establishment of alternative concepts. CONCLUSIONS: Biotechnology is available to apply fast breeding to promising energy plant species. It is important that our valuable arable land is preserved for agriculture. The opportunity to switch from low-income agriculture to biogas production may convince small farmers to adhere to their business and by that preserve the identity of rural communities. PERSPECTIVES: Overall, biogas is a promising alternative for the future, because its resource base is widely available, and single farms or small local cooperatives might start biogas plant operation.     

Images of war: using satellite images for human rights monitoring in Turkish Kurdistan

In areas of war and armed conflict it is difficult to get trustworthy and coherent information. Civil society and human rights groups often face problems of dealing with fragmented witness reports, disinformation of war propaganda, and difficult direct access to these areas. Turkish Kurdistan was used as a case study of armed conflict to evaluate the potential use of satellite images for verification of witness reports collected by human rights groups. The Turkish army was reported to be burning forests, fields and villages as a strategy in the conflict against guerrilla uprising. This paper concludes that satellite images are useful to validate witness reports of forest fires. Even though the use of this technology for human rights groups will depend on some feasibility factors such as prices, access and expertise, the images proved to be key for analysis of spatial aspects of conflict and valuable for reconstructing a more trustworthy picture.