Foraging rules of flower selection applied by colonies of Apis mellifera: Ranking and associations of floral sources

1. Interactions between bees and flowers are historically a key topic of research in biology. Apis mellifera is known to forage on a wide variety of flowers to collect nectar and/or pollen. Until now, resource collection strategies were investigated focusing on the influence of single factors on foraging decisions, such as hive requirements, surrounding vegetation, resource availability, seasonality and interactions with other bees. Despite the vast amount of literature on A. mellifera, we lack a comprehensive view of its flower selection. 2. Our aim was to go beyond specific circumstances in order to identify general criteria for flower selection at species level. Applying data mining techniques (Market Basket Analysis), we found that bees exert a precise flower selection choice mainly driven by their pollen requirements. The bees foraged all over the study area with no obvious preference for the close surrounding vegetation. They selected a restricted number of all the available sources, for nectar as well as for pollen. Apis mellifera chose some floral sources more regularly than others. The most recurrent sources changed in time according to subsequent flowering peaks and often corresponded to anemophilous species. The compelling need for pollen revealed the constant demand of a few distinct floral sources. Plants providing huge quantities of pollen, such as wind-pollinated species, were preferred. When the pollen source also provided a good quantity of nectar, foragers collected both resources on the same species. 3. This work on A. mellifera helps to clarify some of the complex aspects of its floral selection processes, which emerge from studies on single colonies, areas or environmental factors influencing individual foraging behaviours. It also suggests that some established theories on pollinator-flower interactions, such as the role of wind-pollinated species, need revision. © 2012 The Authors. Functional Ecology © 2012 British Ecological Society.