, Volume 99, Issue 7, pp 545–552 | Cite as

Large pollen loads of a South African asclepiad do not interfere with the foraging behaviour or efficiency of pollinating honey bees

  • G. Coombs
  • A. P. Dold
  • E. I. Brassine
  • C. I. Peter
Original Paper


The pollen of asclepiads (Asclepiadoideae, Apocynaceae) and most orchids (Orchidaceae) are packaged as large aggregations known as pollinaria that are removed as entire units by pollinators. In some instances, individual pollinators may accumulate large loads of these pollinaria. We found that the primary pollinator of Cynanchum ellipticum (Apocynaceae—Asclepiadoideae), the honey bee Apis mellifera, accumulate very large agglomerations of pollinaria on their mouthparts when foraging on this species. We tested whether large pollinarium loads negatively affected the foraging behaviour and foraging efficiency of honey bees by slowing foraging speeds or causing honey bees to visit fewer flowers, and found no evidence to suggest that large pollinarium loads altered foraging behaviour. C. ellipticum displayed consistently high levels of pollination success and pollen transfer efficiency (PTE). This may be a consequence of efficiently loading large numbers of pollinaria onto pollinators even when primary points of attachment on pollinators are already occupied and doing so in a manner that does not impact the foraging behaviour of pollinating insects.


Pollen loads Asclepiadoideae Cynanchum ellipticum Foraging efficiency Pollinaria Pollen transfer efficiency 



We thank the Henderson Foundation (GC), Rhodes University Research Committee (CIP, APD) and the South African National Research Foundation (CIP) for funding. We thank the anonymous reviewers for suggestions to improve the manuscript.


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • G. Coombs
    • 1
  • A. P. Dold
    • 1
  • E. I. Brassine
    • 1
  • C. I. Peter
    • 1
  1. 1.Department of BotanyRhodes UniversityGrahamstownSouth Africa

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