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Foraging strategy predicts species-specific patterns of pollen foraging by honey bees and bumble bees
  • Danny Minahan,
  • Johanne Brunet
Danny Minahan
Hebrew University of Jerusalem Robert H Smith Faculty of Agriculture Food and Environment

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Johanne Brunet
USDA-ARS Vegetable Crops Research Unit
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Abstract

Honey bees and bumble bees are generalist eusocial bees that collect resources from a variety of plant taxa. Both bee species have distinct foraging strategies that affect patterns of resource collection, with implications for designing pollinator friendly habitat management schemes. Using a comparative approach, we examined the pollen foraging patterns of the honey bee (Apis mellifera) and common eastern bumble bee (Bombus impatiens) in a suburban-agricultural landscape. We tested predictions stemming from the bees’ known foraging strategies of dance communication or trapline foraging, respectively, and collected pollen from returning foragers of each bee species over five time periods at each of three sites. We quantified the frequency of flower constant foragers, the richness and diversity of pollen collected by a colony, and whether honey bees or bumble bees show preferences by comparing the taxonomic identity of pollen collected to resources available. Analyses were done at the pollen morphotype and plant family levels. Within a foraging trip, honey bees foraged on a single plant family more frequently than bumble bees throughout the summer, except during July, when both species demonstrated a similar frequency of flower constancy. Pollen diversity was greater for bumble bees relative to honey bees, and both bee species collected less diverse pollen in June. Finally, bumble bees preferred the Fabaceae_Tricolporate pollen morphotype (Trifolium repens or Medicago sativa), but avoided Apiaceae, while honey bees foraged randomly showing no evidence of preference. These results support the hypothesis that species level foraging strategies affect how bees exploit pollen resources. Explicitly considering pollinator foraging strategy when designing agri-environment schemes will inform the most appropriate arrangement of floral resources within developed landscapes, thereby promoting both pollinator health and pollination services of bee-dependent crops.