Experimental approach to unexplained mortality of bee colonies in Wallonia

Experimental approach to unexplained mortality of bee colonies in Wallonia

About the project

PROJECT CONTEXT Within the framework of the project "Experimental approach to unexplained mortality of bee colonies in Wallonia (Belgium)"(Nº D32-0075), several beekeeping matrices (honey, wax, bee bread) were taken from the hives and analysed. The results of these analyses clearly indicate that the colonies are contaminated with both insecticides, acaricides but also by many fungicides. However, the exact sources of contamination could not be identified. Only a significant link has been established between dieback and the average number of fungicide residues detected but also with the area of cultivation around the apiary. Thus, the greater the fungicide residue load, the larger the area under cultivation, the greater the likelihood of dieback for the colony. In addition to these bee matrices, trap pollen samples were taken from most of the bee colonies of the apiaries participating in the study. A total of 158 samples were collected in 39 apiaries during the from July to October. They were then grouped according to the month of collection. Following this operation, there are 61 samples left. For each of them, a palynological analysis and an analysis of residues were carried out respectively by CARI (Belgium) and the Floramo laboratory (Italy). The analysis identified more than 30 different botanical families as a source of pollen in the environment of the sampled apiaries. As for the analyses of pesticide residues, they put in evidence 6 fungicide residues (boscalid, cyprodinil, kresoxim-methyl, pyrimethanil, trifloxystrobin, tebuconazole) and 3 insecticides (dimethoate, imidacloprid, thiamethoxam). Given the dates of sampling, July to October, the presence in pollen of some of these contaminants such as boscalid or dimethoate asks us about the agricultural or non-agricultural origin of these residues. For certain molecules, this late detection could be explained by amateur use or by the persistence of the product and the mobilization of it by plants planted after cultivation (ICNAF) or by weeds. In order to clarify this situation, an in-depth analysis of both palynological data and occupation of the area was carried out. of the soil around the apiaries would make it possible to identify the sources of pollen contamination. OBJECTIVE OF THE PROJECT The objective of the project was to cross-reference the results obtained in project Experimental approach to unexplained mortality of bee colonies in Wallonia (Belgium) (Nº D32-0075): (1) palynological origin of trap pollen, (2) pesticide residues in trap pollen and (3) land use around the apiaries in order to identify the sources of contamination of the bee colonies in the different pesticide residues through pollen.

About shared data

Total number of data points shared: 135

Pollen Composition

Pallynological analyses of pollen

Pollen Pesticides

Pesticides analyses from the pollen samples.

Surrounding Land Usage

Surfaces of different type of agricultural land use around the apiaries within buffers of different radius.