The endangered Iris atropurpurea (Iridaceae) in Israel: Honey-bees, night-sheltering male bees and female solitary bees as pollinators

Stella Watts, Yuval Sapir, Bosmat Segal, Amots Dafni

Research output: Contribution to journalArticlepeer-review


Background and AimsThe coastal plain of Israel hosts the last few remaining populations of the endemic Iris atropurpurea (Iridaceae), a Red List species of high conservation priority. The flowers offer no nectar reward. Here the role of night-sheltering male solitary bees, honey-bees and female solitary bees as pollinators of I. atropurpurea is documented.MethodsBreeding system, floral longevity, stigma receptivity, visitation rates, pollen loads, pollen deposition and removal and fruit- and seed-set were investigated.Key ResultsThe main wild pollinators of this plant are male eucerine bees, and to a lesser extent, but with the potential to transfer pollen, female solitary bees. Honey-bees were found to be frequent diurnal visitors; they removed large quantities of pollen and were as effective as male sheltering bees at pollinating this species. The low density of pollen carried by male solitary bees was attributed to grooming activities, pollen displacement when bees aggregated together in flowers and pollen depletion by honey-bees. In the population free of honey-bee hives, male bees carried significantly more pollen grains on their bodies. Results from pollen analysis and pollen deposited on stigmas suggest that inadequate pollination may be an important factor limiting fruit-set. In the presence of honey-bees, eucerine bees were low removal-low deposition pollinators, whereas honey-bees were high removal-low deposition pollinators, because they removed large amounts into corbiculae and deposited relatively little onto receptive stigmas.ConclusionsEven though overall, both bee taxa were equally effective pollinators, we suggest that honey-bees have the potential to reduce the amount of pollen available for plant reproduction, and to reduce the amount of resources available to solitary bee communities. The results of this study have potential implications for the conservation of this highly endangered plant species if hives are permitted inside reserves, where the bulk of Oncocyclus iris species are protected.

Original languageEnglish
Pages (from-to)395-407
Number of pages13
JournalAnnals of Botany
Issue number3
StatePublished - Mar 2013

Bibliographical note

Funding Information:
We thank Haim Ashkenazi, Naomie Bensoussan, Caroline Cawley, David Firmage, Itay Gerlitz, Richard Lewis, Elisa Mancuso and Yuval Shimrat for field and laboratory assistance; Stefan Risch and Achik Dorchin for identification of Eucerini and Christopher O’Toole for Anthophorini. Comments by Jeff Ollerton, Jane Stout and two referees greatly improved the manuscript. This research was supported by the Israeli Science Foundation (grant no. 768/08) and from The Henk and Dorothy Schussheim Fund for Ecological Research in Mt Carmel.


  • Apis mellifera
  • Endangered
  • Iris atropurpurea
  • eucerine bees
  • night-sheltering
  • pollen deposition
  • pollen removal
  • pollen viability
  • pollination
  • pollinator effectiveness
  • solitary bees
  • stigma receptivity

ASJC Scopus subject areas

  • Plant Science


Dive into the research topics of 'The endangered Iris atropurpurea (Iridaceae) in Israel: Honey-bees, night-sheltering male bees and female solitary bees as pollinators'. Together they form a unique fingerprint.

Cite this