Variability in nectar production and standing crop, and their relation to pollinator visits in a Mediterranean shrub

Tamar Keasar, Adi Sadeh, Avi Shmida

Research output: Contribution to journalArticlepeer-review


Nectar standing crops in flowers within an individual plant are often highly variable. This variability may be a by-product of the foraging activity of insect pollinators. Alternatively, plants may be selected to produce highly variable rewards to reduce consecutive visitation by risk-averse pollinators, thus diminishing within-plant pollen transfer. This study evaluated the roles of pollinator control vs. plant control over nectar variability in the bee-pollinated shrub Rosmarinus officinalis L. (Lamiaceae). We sampled nectar production, standing crop and pollinator visits in three shrubs of one population over 17 days during one blooming season. Nectar production rates were highly variable (CV = 1.48), and increased after rainy days. Nectar standing crops were even more variable (CV = 2.16), decreased with increasing temperatures, and increased with time since the last rain. Pollinator visit rates decreased with variability in nectar standing crops, increased with flower number per shrub, and were unaffected by variability in nectar production rates. Repeated sampling of marked flowers revealed no correlation between their nectar standing crops and production rates. These findings support the role of reward variance in reducing pollinator visits, but suggest that plants are not in complete control of this variability. Rather, plant-generated variability can be modified by intensive foraging activity of pollinators. Such pollinator control over nectar variability is likely to reduce the selective advantage of plant-generated reward variation.

Original languageEnglish
Pages (from-to)117-123
Number of pages7
JournalArthropod-Plant Interactions
Issue number2
StatePublished - Jun 2008

Bibliographical note

Funding Information:
Acknowledgements The field work was supported by the Jewish National Fund. Data analysis and writing were supported by the research group on Evolution and Game Theory at the Institute of Advanced Studies, The Hebrew University. Tom de Jong commented on the manuscript. The experiments comply with the current laws of the State of Israel.


  • Geitonogamy
  • Honeybee
  • Nectar variability
  • Pollination
  • Rosmarinus officinalis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Agronomy and Crop Science
  • Insect Science


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