Role of floral resources in the conservation of pollinator communities in cider-apple orchards

Pollinators are generally assumed to be in decline but a proper habitat management could help to conserve pollination services. In 2012 we surveyed the groundcover in nine cider-apple orchards to (I) identify the floral and faunal communities present in the ground floor, (II) assess the attractiveness of the local spontaneous flowers to insects and (III) determine the role that the flower community may play for the conservation of the associated arthropods in general and of pollinators in particular. The apple orchards provided a continuous succession of floral resources in the groundcover with differences among orchards in the abundance, richness and diversity of flowers. Flowering plant species were visited by a wide variety of insects, mostly from the orders Hymenoptera (70%) and Diptera (25%). Wild bees accounted for 27% of hymenopterans and hoverflies for 30% of dipterans. Flowering plants differed in the number of taxa they attracted and in their attractiveness for particular insect groups and for insects as a whole. A total of 16,159 arthropods were collected from the groundcover, and 2064 individuals belonged to taxa involved in the pollination. Pollinators and arthropods (exemplified by hemipterans and coleopterans) differed between orchards and periods and were affected by the plant community. Plant species richness and the abundance of some plant species favored the presence of both pollinators and arthropod assemblages while flower abundance had only a marginal effect on those communities. Pollinators were also affected by plant diversity. Among-orchard differences in the plant community suggest that management recommendations must be site-specific to ensure the permanent availability of diverse floral resources for the arthropod community and for pollinators in particular. Therefore, a proper groundcover management could provide benefits for apple growers by improving pollination services.