Pollination Ecology of Oil-Collecting Bees

Oil-collecting bees engage in one of the most specialised plant–pollinator mutualisms, centred on floral glands known as elaiophores that secrete non-volatile lipids. These floral oils serve multiple purposes: they attract and reward female bees, which harvest oils to line brood cells, manufacture larval provisions and construct nest partitions. Oil flowers are found across diverse angiosperm lineages— prominently in Malpighiaceae, Iridaceae and Plantaginaceae— and often exhibit bilateral symmetry, nectarlessness and elaborate glandular morphology. Bees in tribes such as Centridini, Tapinotaspidini and Redivivini possess dense brushes of specialised hairs, scopae or comb-like structures to absorb and transport oils. The ecology of this system spans from floral chemistry and pollinator foraging behaviour to reproductive success of host plants and the resilience of bee populations under habitat change. Understanding the drivers of floral oil evolution and the sensory adaptations of oil bees underpins conservation of these interdependent taxa and informs sustainable management of tropical and subtropical ecosystems.

Research from Nature Portfolio

Recent studies have demonstrated that diacetin, a volatile acetylated glycerol, functions as a private olfactory signal exclusive to oil-collecting bees. Electrophysiological recordings have shown that only oil bees detect diacetin, using it as a reliable cue to locate oil-secreting flowers amid a background of non-oil flora. Behavioural assays confirm diacetin’s role in guiding female bees directly to elaiophores, effectively creating a one-to-one communication channel between oil plants and their specialised pollinators. This finding elucidates the chemical underpinnings of host specificity and advances our understanding of sensory co-evolution in mutualistic networks.

Pollination Ecology of Oil-Collecting Bees publication trend

The graph below shows the total number of articles in pollination ecology of oil-collecting bees across all publications each year (not limited to Nature Index journals).

Technical terms

Elaiophore: A specialised floral gland that secretes non-volatile oils to reward oil-collecting bees.

Oil-collecting bee: A bee belonging to certain tribes (e.g. Centridini, Tapinotaspidini) with specialised hairs and structures for harvesting and transporting floral oils.

Diacetin: A volatile acetylated glycerol compound emitted by oil flowers, serving as a private chemical cue for oil-collecting bees.

Zygomorphic: Describing flowers with bilateral symmetry, a common feature of many oil-rewarding species.

Trophic niche: The suite of dietary resources a species exploits within its environment, encompassing pollen, nectar and oil.

References

1. Unravelling the Homology between Calycine Glands in Malpighiales: New Data from Basal Malpighiaceae. Plants (2024).
2. Range and trophic niche overlap of two sympatric species of floral oil collecting bees in a fragment of dry forest. Frontiers in Bee Science (2024).
3. Diacetin, a reliable cue and private communication channel in a specialized pollination system. Scientific Reports (2015).
4. Elaiophores: their taxonomic distribution, morphology and functions. Acta Botanica Brasilica (2017).