Honey bees and Sesame

Honey bees and plants have a mutualistic relationship, meaning they both benefit from each other. The main service honey bees provide to plants is pollination, and in exchange, bees receive delicious nectar from the flowers of the plants. When a bee enters a flower to take some of the nectar, its body gets covered in pollen. The bee passes the pollen from the anther (male structure) of a flower, to the stigma (female structure) of a different flower. Thus helping the plant to produce offspring. To be more specific, this process is called cross-pollination because flowers of different plants are involved.

Not all plant species are suitable for honey bee pollination. Some plants have flowers that have evolved to attract a specific group of pollinators. Many of the pollinators are insects: bees, flies, beetles, butterflies, moths, etc., but bats and birds, like hummingbirds, also do a great job pollinating.

Sesame is an oil seed crop that attracts different insect pollinators. However, it can self-pollinate. In other words, pollen can get from the flower’s male structures to the flower’s female structures of the same plant without the need of a pollinator. So, why do sesame flowers attract pollinators if they can self-pollinate?

Even though sesame and other plants can self-pollinate, self-pollination doesn’t yield the same results as cross-pollination. With cross-pollination, plants can have better seed production and seed quality. The fact that self-pollination happens with flowers of the same plant has a very limiting effect on genetic variation. Cross-pollination is what ultimately allows for the processes of evolution to happen and for new varieties to appear. Cross-pollination can also lead to an earlier harvesting time.

Do pollinators have a preference in terms of what plants they pollinate? They might. Nectar and pollen from different flowers can vary in nutrient content, and there could be other environmental factors that affect which plants get pollinated. A study in Egypt, in the region of Fayoum, looked at pollen collection by honey bees for 2 years, and found that the pollen came from 24 different plant species, most of it coming from sesame and maize.  

Both sesame and honey bees get great benefits from their mutualistic relationship. And as consumers, we get to enjoy the end result. Time to have some tahini!

Interesting fact: Sesame flowers are visited by insect pollinators most frequently between 11am and 1pm, and then between 1pm and 3pm. That’s when the flow of nectar is at its highest in sesame plants.

References:

Rahman, M. Z., Reza, M. E., Hossain, M. S., Ali, M. R., & Hossain, M. S. (2022) Effect of bee pollination on yield of sesame. Ecology Journal. 4 (1) : 1-7

Kamel, S., Mahfouz, H., Blal, A. E. H., El-Wahed, A., Said, M., & Mahmoud, M. F. (2015). Foraging activity of four bee species on sesame flowers during two successive seasons in Ismailia Governorate, Egypt. Pestic. Phytomed. (Belgrade), 28(1), 2013, 39–45 DOI: 10.2298/PIF1301039K

Abou-Shaara H. F., (2015). Potential Honey Bee Plants of Egypt. Cercetări Agronomice în Moldova

Vol. XLVIII , No. 2 (162).

Degefa, F. T. (2019). Review on sesame (Sesamum indicum L.) breeding in Ethiopia. J Biol Agric Health, 9(17), 39-45.