1,721,009 research outputs found
Simbologie sonore
No full textRassegna di alcune fra le più evidenti "simbologie sonore" (vocali e strumentali) riscontrabili nella partitura del Singspiel "Die Zauberflöte" di W. A. Mozart (1791
3D-modelling and prediction by WHIM descriptors. Part 8. Toxicity and physico-chemical properties of environmental priority chemicals by 2D-TI and 3D-WHIM descriptors.
No full textMathematical Models for the Comprehension of Chemical Contamination into the Hive
No full textHoneybees are very sensible organisms and their vulnerability toward chemical pollution is an priority environmental issue. In this chapter the importance and the fundamental of a mathematical model able to predict the fate of chemicals into the hive is described. The ‘Hive model’ presented here is able to consider different contamination pathways: from inside the hive via pesticide treatments against bee pests, or from outside, by means of the eventual contamination present in nectar, pollen, resin, water, air or vegetation. The input parameters of the model are the physical-chemical properties of the compound and the major characteristics of the hive ecosystem, from which it calculates contamination residues in bee products (honey, pollen, royal jelly, wax and propolis) over time. The model can be applied to all non ionic chemicals with a measurable vapour pressure (volatile or semi-volatile compounds). The model was validated with contamination data in bees, wax and honey following tau-fluvalinate application in two experimental hives. The comparison between measured and modelled data over a period of six months was very good. Even if more experimental data should be provided for a better calibration of the model, it seems to correctly quantify the main contamination pathways from outside and within the hive
Field trial for evaluating the effects on honeybees of corn sown using Cruiser® and Celest xl® treated seeds
No full textA first field study was conducted to investigate the possible adverse effects that seeds dressed with neonicotinoid insecticides pose to honeybees during sowing. It was observed that in the exposure hives bee mortality increased on the day of sowing and that the number of foraging bees decreased the days after the sowing. The corn sowing posed a significant threat to honeybees, with thiamethoxam being the most probable toxic agent. A theoretical contact exposure was calculated for a bee when flying over the sown fields, revealing a dose of 9.2 ng bee(-1) close to the contact LD50 of thiamethoxam
Managing Pesticide Risk for Non Target Ecosystems with Pesticide Risk Indicators. A Multicriteria Approach
No full textPredicting pesticide fate in the hive (part 2): development of a dynamic hive model
No full textA new hive model is proposed for the assessment of the distribution and fate of pesticides in the hive ecosystem. Based on the chemical used, the model draws a dynamic picture of pesticide contamination in the hive, calculating contamination trends and concentration levels in the various hive components (e.g. bees, wax and honey). The proposed model is validated using empirical data on tau-fluvalinate residues in bees, wax and honey. It predicts with good approximation both the trends over time and the contamination levels of the pesticide in the various hive components. We have developed most of the parameters and equations used in this model. Although they will require further experimental testing, they provide realistic predictions that are consistent with the experimental data. The proposed model is a useful tool for predictive purposes and improves our understanding of contamination phenomena in the hive
Coumaphos distribution in the hive ecosystem : case study for modeling applications
No full textPesticides are currently used inside hives, against the honeybee parasite Varroa destructor, producing unwanted contamination effects. To assess the distribution and fate of one of these pesticides (coumaphos), two experimental hives were treated with Perizin (the commercial product containing the active ingredient coumaphos). Samples of honey, wax, pollen, adult bees and larvae taken before treatment and up to 104 days afterwards, showed diffuse contamination. Wood hedges and wax bridges, where the pesticide solution was applied, were analysed as well. A mass balance was calculated, yielding a recovered amount of around 60% just after treatment and 38% 1 month later. Directly contaminated surfaces and wax contained the highest amount of residues. Wax and honey contained different amounts (10, and 0.1% respectively) but both retained residues for long time. Bees ingest most of the product just after treatment, then rapidly eliminate it by metabolism, advection and deposition processes. On the basis of analytical results, a simple model (level I of the fugacity model) was applied to the hive system for different pesticides (coumaphos, malathion, fluvalinate and bromopropylate). Predicted concentrations in wax and honey were compared with those measured, indicating the good predictive capability of this approach
- …
