Food selection dynamic by honeybees in agricultural landscape
Abstract
Agricultural landscapes have been strongly changed because of farming intensification for several centuries. These landscape changes are mainly related to a decrease in semi-natural habitats, standardisation of land use and an increase of field area, which have created some intensive cereal farming systems. Honeybee (Apis mellifera L.) is the main crop pollinator. Nectar constitutes the energy resource and is transformed in honey for storage whereas pollen is the main protein resource for the physiology development. Pollen is little stored and the supply must follow a flow tended between need and collection. However, during the breeding season, the succession of flowering crops leads to strong spatio-temporal dynamics of food resources. In such an environmental context, which food choices make honeybees and which influences will they have on the dynamics of pollen harvest during these seasons? Thanks to the large spatial scale of our experimental design on a 200 colonies monitoring, set up in an intensive cereal farming system, we clearly assume that a bimodal temporal pattern of pollen harvest exists. The first peak is linked to the blooming of spring plants (in May) and the second one to the simultaneous flowering of sunflower and maize (in July). We observe that species which are present in hedgerows and forest edges were strongly selected as well as weeds such as the poppy. On the contrary, the rapeseed is little selected for its pollen resource while the maize which is anemophilous pollinated, is strongly chosen.