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Do honeybees cross-pollinate macadamias?
Quick find: this post is based on the published summary (abstract) of the study, not the full paper.
Only 15% of the honeybees sampled in a macadamia orchard were carrying pollen from more than one identified macadamia cultivar. Most carried pollen from only one, whichever hive location they came back to and whether they were sampled early in flowering or at peak flowering.
Macadamia is a predominantly self-sterile tree crop, and many self-sterile crops rely on animals carrying pollen between different cultivars. That means a forager such as a honeybee may need to visit, and carry the pollen of, more than one cultivar to be an effective pollinator. The authors say there has been little understanding of how many foragers actually do, so a team from Griffith University and Queensland University of Technology checked the pollen on honeybees coming home to the hive (Singla et al., 2026).
What this means for your grow
For macadamia growers, the finding is that the honeybees in this orchard mostly carried one cultivar’s pollen, so, in the authors’ view, most of their foraging visits to flowers were unlikely to have resulted in cross-pollination. The authors suggest interplanting polleniser trees among the main cultivars to increase the number of honeybees carrying cross-pollen. The published summary does not report that idea being tested, and it does not report nut set or yield. It is also one orchard, and the summary does not say where it was.
What did they test and find?
- The bees: honeybees returning to their hive with pollen, at two locations in the orchard. One location was close to only one macadamia cultivar; the other was between two macadamia cultivars.
- The timing: bees were sampled early in the flowering period, when floral resource availability was lower, and at peak flowering, when it was higher.
- The method: the team identified the cultivars carried by individual honeybees with a SABER-MassARRAY method, which distinguishes cultivar-specific SNPs in pollen DNA.
- One cultivar for most bees: most honeybees carried pollen from only one identified macadamia cultivar, regardless of the hive location and the time within the flowering period.
- Few with cross-pollen: only 15% of the honeybees were carrying pollen from more than one identified macadamia cultivar.
What could it mean?
The authors conclude that most honeybee foraging visits to flowers in the orchard were unlikely to have resulted in cross-pollination, and that polleniser trees could be interplanted among the main cultivars in macadamia orchards to increase the number of honeybees carrying cross-pollen and increase their pollination efficiency. For now this is a result for commercial macadamia growers and pollination researchers, not something to try at home.
What were the limitations?
Limitations are not reported in the published abstract.
Trial details
- Who: School of Environment and Science, Griffith University, Brisbane, Queensland, and School of Biology and Environmental Sciences, Queensland University of Technology, Brisbane (the authors’ affiliations, not the trial site).
- Where: an orchard of macadamia. Facility type: orchard.
- Crop: macadamia, described as a predominantly self-sterile tree crop.
- Pollinator: honeybees returning to their hive with pollen.
- Design: two hive locations (close to only one macadamia cultivar, or between two macadamia cultivars), each sampled early in the flowering period (lower floral resource availability) and at peak flowering (higher resource availability). Pollen on individual honeybees identified to cultivar with a SABER-MassARRAY method that distinguishes cultivar-specific SNPs in pollen DNA.
- Results: most honeybees carried pollen from only one identified macadamia cultivar, regardless of hive location and time within the flowering period; 15% carried pollen from more than one identified macadamia cultivar.
- Funding: Horticulture Innovation Australia (awards PH16001 and PH20001), as listed in the paper’s Crossref record.
- Publication: Horticulturae 12(6), 648, published 22 May 2026, https://doi.org/10.3390/horticulturae12060648. Licence: CC BY 4.0.
- Not reported in the published abstract: where the orchard was (country, region or site); the macadamia cultivars; the orchard’s size and planting layout; the year and dates; the number of hives and of honeybees sampled; how far the hives were from the trees; statistics; nut set or yield; and conflicts of interest.
Links
- The study: Very Few Honeybees Carry Cross-Pollen in a Self-Sterile Tree-Crop Orchard
- The institution: Stephen Trueman, Griffith Experts, Griffith University
References
- Singla, A., Wallace, H. M., Chakma, N., Farrar, M. B., Bai, S. H., & Trueman, S. J. (2026). Very few honeybees carry cross-pollen in a self-sterile tree-crop orchard. Horticulturae, 12(6), 648. https://doi.org/10.3390/horticulturae12060648