Review on imidacloprid diffusion route and a case study: from apple orchard to the honey bee colony matrices

Honey bees play a pivotal role in natural and rural ecosystems by providing human and animal food sources through pollination services. However, in cultivated areas, they can be exposed to the chemicals utilized for crop protection. Neonicotinoid insecticides can adversely affect honey bee colonies impairing their survival, immunity and biological activities at lethal and sublethal doses. For this reason, neonicotinoids, together with other stress factors, like pathogens (e.g. viruses and Varroa mites), climate change and food shortage, are considered one of the causes of worldwide colony losses. Nevertheless, the natural way of entry and diffusion of these pesticides in field colonies is not completely clear. Here, we wanted to fill this gap by studying the diffusion route of imidacloprid and its metabolites by analysing different matrices collected from honey bee colonies used for pollination of apple orchards, in the framework of applied Integrated Pest Management strategies. Pollen, honey bees, honey, royal jelly, bee wax and bee bread were sampled from 6 honey bee colonies placed in two different apple orchards before blooming, exposed to chemicals application and removed from the site after that. Samples were analysed using a liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) in order to detect imidacloprid, olefin imidacloprid and 5-hydroxy imidacloprid. The results demonstrate that the primary way of entrance of imidacloprid was the pollen transported by foragers, while the main accumulation matrices were bee bread, honey and wax. These findings allow us to hypothesize that the accumulation of this insecticide, especially in bee bread, the main larval food, could potentially impact negatively on honey bee wellbeing at the adult stage. Moreover, our data could implement the honey bee colony simulato

Adaptabilidade e estabilidade das cultivares de trigo avaliadas no ensaio estadual do Rio Grande do Sul, no ano 2007.

Área: Melhoramento, Aptidão Industrial e Sementes

THE ROLE OF MINERAL NUTRITION ON YIELDS AND FRUIT QUALITY IN GRAPEVINE, PEAR AND APPLE

ABSTRACT Fertilization of temperate fruit trees, such as grapevine ( Vitis spp.), apple ( Malus domestica), and pear ( Pyrus communis) is an important tool to achive maximum yield and fruit quality. Fertilizers are provided when soil fertility does not allow trees to express their genetic potential, and time and rate of application should be scheduled to promote fruit quality. Grapevine berries, must and wine quality are affected principally by N, that regulate the synthesis of some important compounds, such as anthocyanins, which are responsible for coloring of the must and the wine. Fermenation of the must may stop in grapes with low concentration of N because N is requested in high amount by yeasts. An N excess may increase the pulp to peel ratio, diluting the concentration of anthocyanins and promoting the migration of anthocyanins from berries to the growing plant organs; a decrease of grape juice soluble solid concentration is also expected because of an increase in vegetative growth. Potassium is also important for wine quality contributing to adequate berry maturation, concentration of sugars, synthesis of phenols and the regulation of pH and acidity. In apple and pear, Ca and K are important for fruit quality and storage. Potassium is the most important component of fruit, however, any excess should be avoided and an adequate K:Ca balance should be achieved. Adequate concentration of Ca in the fruit prevents pre- and post-harvest fruit disorders and, at the same time, increases tolerance to pathogens. Although N promotes adequate growth soil N availability should be monitored to avoid excessive N uptake that may decrease fruit skin color and storability