Competition between wild bees and manged honeybees : a review of floral preferences

Abstract: The decline of wild pollinators has given ground for a debate on the effects of managed honeybees to wild populations. Even though honeybees are native to some areas, management and domestication has had an indisputable effect on their foraging behaviour and thus the potential effect on surrounding taxa. Whilst a majority of wild species are solitary, honeybees are social and exhibits a complex social behaviour. Previous studies have shown that honeybees displace foraging wild bees rather than deplete foraging resources or direct interference. This could likely affect wild bees’ ability to collect sufficient floral resources and thus decrease fitness. In order to bring awareness to Swedish wild bees that risk potential negative effect of managed honeybees I performed a review of scientific literature on honeybee preference and compared the result with floral preference of wild species. I targeted wild bees with a red-list status of Near threatened (NT) and Vulnerable (VU) and found that a majority of these species forage on flowers that are also preferred by honeybees. According to the literature honeybees prefer open flowers that offers a large reward of pollen or nectar. This includes most flowers from the Asteraceae, Fabaceae and Brassicaceae family. The Asteraceae and Fabaceae families are also preferred by a majority of red-listed wild species. Most wild bee species are specialized on one or more specific plant genera within these families, which reduce risk for competition. Honeybees does not present this tactic and instead visit a lot of different flower but in shorter bouts, so they risk intrude on several species of wild bees. To measure effects on fitness, direct measurements like number of brood or offspring is needed and this is not provided by this review. Instead the information provided here clearly acknowledge a substantial resource overlap for wild species already negatively affected by lack of preferred flowering plants. Adding competition from large colonies should be considered a significant threat to wild populations in some areas and thus, placement of manged honeybees should be evaluated before executed.