Feeding with plant powders increases longevity and body weight of Western honeybee workers (Apis mellifera)

Beekeepers routinely substitute honey from managed western honeybees, Apis mellifera, colonies with sugar water post-harvest, potentially leading to malnutrition. Although nutritional supplements have been created, a general consensus on proper colony nutrition for beekeeping has yet to be reached. Thus, finding easily obtainable fortified A. mellifera food alternatives is still of interest. Here, we test plant powder-enriched food supplements since a priori evidence suggests plant extracts can enhance dry body weight and longevity of workers. Freshly emerged workers were kept in hoarding cages (N=69 days) and fed either with 50 % (w/v) sucrose solution alone or additionally with one of 12 powders: Laurus nobilis, Quercus spp., Curcuma longa, Hypericum spp., Spirulina platensis, Calendula officinalis, Chlorella vulgaris, Melissa officinalis, Moringa oleifera, Rosa canina, Trigonella foenum-graecum, and Urtica dioica (N=2028 workers total). The dry body weight was significantly increased in Quercus spp., Hypericum spp., Spirunlina platensis, Mellisa officinalis, Moringa oelifera, and Trigonella foenum-graecum treatments. Further, the longevity was significantly increased in Quercus spp., Curcuma longa, Calendulae officinalis, Chlorella vulgaris, Melissa officinalis, Rosa canina, Trigonella foenum-graecum, and Urtica diocia treatments. Given that plant extracts can enhance A. mellifera health, plant powders possibly provide additional macro- (i.e. proteins, lipids, peptides) and micronutrients (minerals and vitamins) thereby enhancing nutrient availability. Further investigations into the mechanisms underlying these effects and field studies are recommended to validate these findings in real-hive scenarios.

Methods
The data were collected during hoarding cage experiments conducted at the Institute of Bee Health in 2022. The data have been processed using the opensource software R (version 4.3.2 (2023-10-31)).