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Presseinformation: Honey bees fly to organic farming
Nr. 123 - 21.08.2024
Researchers confirm positive effects of organic farming and flower strips for bee colonies
Honey bees are valued both for their honey and their ability to pollinate crops. However, populations are suffering from the loss of areas of wild flowers in intensive farming, pesticide applications and from the influence of pathogens, so it is all the more important to understand what keeps them healthy. Researchers at the Universities of Halle and Göttingen discovered that organic farming and flower strips can promote the health of honey bees. Colonies grow stronger and are generally healthier near these areas. The researchers suggest that the reason for this is likely to be that the insects have a varied food supply there and are less contaminated by pesticides. The results were published in the Journal of Applied Ecology.
The team analysed data from 64 bee colonies in northern Germany. Each area had different proportions of the following land use types: organically farmed fields, semi-natural habitats, and flower strips – meaning strips of land sown with flowering plants for pollinators and other animals. The researchers then recorded the development of the bee colonies, namely their growth and the infestation by parasites, for a year. Particular attention was paid to the Varroa mite: this is one of the most dangerous pests to harm honey bees; they can transmit viruses that are fatal to bees. Towards the end of the research period, the team analysed the relationship between the development of the bee colonies, their state of health and the proportion of land covered by the three land use types.
Organic farming had the greatest positive effect: the parasite load on the bee colonies declined with increasing proportions of organic farming in the landscapes, which led to better colony growth. The researchers suspect that one reason for this is that organic farming uses fewer pesticides and relies on other ways to protect plants. Flower strips in the landscape also had advantages for the honey bees: the number of Varroa mites was lower in areas with many flower strips. This could be due to the fact that a diverse pollen and nectar diet provided by different flowering plants strengthens the honey bees' immune system. Although perennial semi-natural habitats promote biodiversity and provide a habitat for many animals, they tended to have disadvantages for honey bees in the study: larger areas generally meant a higher infestation of Varroa mites. And unlike flower strips, the areas are not designed to provide a continuous supply of food for honey bees and other pollinators.
"A large amount of organic farming and many flower strips not only promote the growth of honey bee colonies through more flowers and less exposure to pesticides, but also reduce the threat to the colonies from the Varroa mite and transmitted pathogens," explains Professor Catrin Westphal, an agroecologist at the University of Göttingen. "Through our interdisciplinary collaboration and the combination of agroecological and genetic methods, we can show conclusively that the management of agricultural landscapes has complex effects on the development of honey bee colonies, as well as on their health." These findings could help to better align landscape management with the development and health of bees and other pollinators. Until now, it was only known that a higher proportion of organic farming, more flower strips and near-natural landscapes close to fields had positive effects on various animal and plant species. Interactions between bees and their parasites, on the other hand, have rarely been investigated.
This project was funded by the Federal Ministry of Food and Agriculture (BMEL) and the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).
Original publication: P Pluta et al. Organic farming and annual flower strips reduce parasite prevalence in honey bees and boost colony growth in agricultural landscapes. Journal of Applied Ecology 2024. DOI: 10.1111/1365-2664.14723
Contact:
Professor Catrin Westphal
University of Göttingen
Faculty of Agricultural Sciences
Department of Crop Sciences - Division of Functional Agrobiodiversity & Agroecology
Grisebachstraße 6, 37077 Göttingen
Telephone: +49 (0)551 / 39-28275