Chemical recognition of queen cells by honey bee workersApis mellifera (Hymenoptera: Apidae)

Summary Honey bee workers are able to nurse or to destroy and thus to recognize the capped queen cells containing a pupa. Fatty acid esters, especially methyl oleate, methyl palmitate and ethyl oleate were found in significant amounts on the queen pupal cuticle. Methyl oleate, the major component, along with smaller amounts of methyl linoleate and methyl linolenate, were involved in the recognition of queen cells by workers. In natural conditions of the colony, queen cells containing a paraffin pupal lure with methyl oleate were accepted 5.9 days by workers, releasing about 1.8 queen pupa equivalents during that period, when control cells (without ester) were kept only 2.1 days. Although these esters are non specific to honey bees, they are of great importance in social regulation of the honey bee colony.     

Sowing simulation tests of a pneumatic drill equipped with systems aimed at reducing the emission of abrasion dust from maize dressed seed

The utilization of dressed seed for spring sowing is a widespread practice to control some pests with reduced doses of chemical products. However some insecticides employed in maize seed dressing, namely belonging to the neonicotinoid family and fipronil, have been claimed to play a role in the decline of honeybees (Apis mellifera L.). Pneumatic drills used in maize sowing are charged with contributing to the dispersion of the abrasion dust produced by dressed seeds, favoring the contamination of the honeybee habitat. Different devices similar to air deflectors have been introduced on pneumatic drills in order to reduce dust drift. During previous field tests carried out by the authors during recent years reduction of dust concentration both in the air and at soil surface has been shown as a consequence of their application. As field tests are affected by the variability of environmental parameters (namely wind speed and direction) the results are not always reliable, comparable and of a general validity. This paper refers to a sowing simulation test system in which pneumatic drills can be tested at a fixed point under controlled conditions of the main environmental parameters. In the test area, protected by external influences, artificial wind conditions are created by means of a fan. The drill, suitably placed in the test area, operates the seed distribution "sur place" by means of an electric engine connected to the drill's driving wheel. A 22.5 m long sampling area, leeward with respect to the drill position, has been identified. Along the sampling area a series of Petri dishes has been placed, with the aim of capturing the depositing dust and providing the concentration of the active ingredients (a.i.) at ground level. At the same time, three air samplers with PTFE diskette filters have been used for the detection of the a.i. The test system has been used for the test of a pneumatic drill, equipped with and without air deflectors, using maize seed dressed with four a. i. (imidacloprid, clothianidin, thiametoxam, fipronil). The results showed regularly decreasing of the concentrations as distance increased, both in the air and at ground level. Moreover, the difference determined by the adoption of the drift reducing device (air deflectors) resulted clear and it can be quantified at around 50 % of the a.i. amounts observed without deflectors. Finally, the paper proposes a data processing method that, from the values observed at fixed point, provides the theoretical a.i. concentration behavior that would occur in field, under the same conditions of wind speed and direction and working speed. The obtained results are coherent with previous field test.     

Decoupling MSW settlement into mechanical and biochemical processes – Modelling and validation on large-scale setups

Forecasting settlements of non-hazardous waste is essential to ensure the integrity and durability of landfill covers over time. Over a short time span, the survey of settlements may also contribute to the investigation of the biodegradation processes. This paper addresses secondary settlements of Municipal Solid Waste (MSW), a heterogeneous and time-evolving material.An analysis of available experimental data from different pilots and the literature was conducted to quantify the influence of biodegradation on MSW secondary settlements. After making assumptions about the various features of the waste and their constitutive relationships, a one-dimensional biomechanical model to predict the secondary settlement has been developed. The determination of the total secondary settlement was obtained by the addition of two separate parts, the mechanical settlement, due to creep, and the biochemical settlement, due to the degradation of the organic matter. The latter has been evaluated based on the observed biogas production. Using the data from different recent large-scale experiments that provide a monitoring of biogas production, a method for predicting the biochemically-induced settlements is proposed and validated on these tests. The relative contributions of mechanical and biochemical settlements are also calculated and discussed as a function of waste pre-treatment and operation conditions (biological pre-treatment, shredding, leachate injection). Finally, settlement may be considered as a relevant indicator for the state of biodegradation.     

Reaction kinetics formulation with explicit radiation absorption effects of the photo-Fenton degradation of paracetamol under natural pH conditions

Environmental Science and Pollution Research - The degradation of paracetamol (PCT) in an aqueous medium using the Fenton and photo-Fenton reactions was investigated. The aim of this research was...