The neglected bee trees: European beech forests as a home for feral honey bee colonies

Abstract

It is a common belief that feral honey bee colonies (Apis mellifera L.) were eradicated in Europe through the loss of habitats, domestication by man and spread of pathogens and parasites. Interestingly, no scientific data are available, neither about the past nor the present status of naturally nesting honeybee colonies. We expected near-natural beech (Fagus sylvatica L.) forests to provide enough suitable nest sites to be a home for feral honey bee colonies in Europe. Here, we made a first assessment of their occurrence and density in two German woodland areas based on two methods, the tracing of nest sites based on forager flight routes (beelining technique), and the direct inspection of potential cavity trees. Further, we established experimental swarms at forest edges and decoded dances for nest sites performed by scout bees in order to study how far swarms from beekeeper-managed hives would potentially move into a forest. We found that feral honey bee colonies regularly inhabit tree cavities in near-natural beech forests at densities of at least 0.11–0.14 colonies/km2. Colonies were not confined to the forest edges; they were also living deep inside the forests. We estimated a median distance of 2,600 m from the bee trees to the next apiaries, while scout bees in experimental swarms communicated nest sites in close distances (median: 470 m). We extrapolate that there are several thousand feral honey bee colonies in German woodlands. These have to be taken in account when assessing the role of forest areas in providing pollination services to the surrounding land, and their occurrence has implications for the species’ perception among researchers, beekeepers and conservationists. This study provides a starting point for investigating the life-histories and the ecological interactions of honey bees in temperate European forest environments.

Contribution of European forests to safeguard wild honeybee populations

“…In Europe, the western honeybee Apis mellifera exhibits a dual nature as managed and wild species (Requier et al., ). Despite wild populations of A. mellifera being a threatened component of the native fauna, little attention has been paid to these populations (Kohl & Rutschmann, ; Requier et al., ). Currently, Apis mellifera is classified as 'data deficient' in the IUCN Red List of European bees due to a lack of information on wild populations (De la Rúa et al., ).…”

“…Honeybee health issues (Potts et al., ) have primarily been discussed with respect to their impact on beekeeping and crop pollination (Potts et al., ), while wild populations are often not considered and even widely assumed as extinct (De la Rúa, Jaffé, Dall ’Olio, Mūnoz, & Serrano, ; Geldmann & González‐Varo, ; Jaffé et al., ; Meixner, Kryger, & Costa, ). Nonetheless, recent studies have shown that wild colonies of A. mellifera can still be found in Europe (Kohl & Rutschmann, ; Oleksa, Gawronski, & Tofilski, ), underpinning the need to increase knowledge on these populations (Alaux, Le Conte, & Decourtye, ; Requier et al., ; Requier & Crewe, ).…”

“…Forest trees may bear many suitable cavities—either excavated by woodpeckers or as a result of wood decay (Kozák et al., ; Paillet et al., ; Remm & Lõhmus, )—which constitute the primary nesting sites of the wild colonies of A. mellifera (Crane, ; Kohl & Rutschmann, ; Oleksa et al., ). However, the current availability of tree cavities is limited by production‐oriented forest management in Europe (Bütler, Lachat, Larrieu, & Paillet, ; Paillet et al., ).…”

“…Across the main European forest types, unmanaged areas generally host far more tree cavities than their managed counterparts (Kozák et al., ; Paillet et al., , ). Records of wild honeybee colonies in tree cavities are mainly restricted to Northern Poland (Oleksa et al., ) and central Germany (Kohl & Rutschmann, ). Although wild colonies were also reported to colonize man‐made tree cavities in Southern Urals forests (Ilyasov, Kosarev, Neal, & Yumaguzhin, ) and suspected in France (Bertrand et al., 2015), Ireland, and Italy (Jaffé et al., ), there is a critical lack of field data on the presence of honeybee occupied tree cavities.…”

Bumblebee Honey in the Nordic Countries

“…The western honey bee, Apis mellifera L., is the only species of honey bee native to Europe. Its colonies have been harvested since antiquity (Bodenheimer 1951;Crane 1999;Kohl and Rutschmann 2018;Sandklef 1946). Apiculture in the Nordic and neighboring countries has relied for centuries on the domestic honey bee for honey and wax production as well as for pollination (Sandklef 1946;Van Engelsdorp and Meixner 2010;Williams et al 1995).…”