Is it surprising that chocolate lovers around the world have a little fly to thank every time they take a bite of delicious chocolate? Granted, saying fly and chocolate in the same sentence is rather unappetizing, but it must be done.
Chocolate is made from the seeds of the cacao tree (Theobroma cacao), native to South America's tropical rain forest. The Mesoamericans were the first to discover how to process the cacao seeds to get the substance we know distinctively as chocolate. The historical origin of Theobroma cacao in its wild state was the upper Orinoco and Amazon river region,1 and from there it spread to Guiana, Central America and southern Mexico. The white cacao flowers, which when pollinated produce the prized seed pods, do not grow from the tree's branches. Instead they grow directly out of the tree's trunk. This unusual formation is referred to as "cauliflory" by botanists, and most likely plays a role in the tree's insect pollination.2 The flowers are very small and intricate in their design, so it makes sense that they would need a small pollinator.
Some mystery still surrounds the pollination of the precious Theobroma cacao. The tiny pollinators are midges -small, gnat-like flies, in the family Ceratopogonidae, various species of Euprojoannisia and Forcipomyia.3 The midges tend to be most active in their pollination at dusk and dawn, correlating with the opening of the cacao flowers, which are fully open just before dawn.4
On cacao plantations the trees produce many flowers, but few seed pods result. Natural pollination rates are low because it is done by insects that are well adapted to the shady rain forest environment and not the open spaces of well kept commercial plantations. The pollinators do not respond well to the unnatural arrangement of the cacao trees or the flowering behaviour of plantation cacao trees.5 This imbalanced situation exists due to cacao cultivation practices that have been used for hundreds of years. To tackle the problem at hand, that would threaten the chocolate industry, farmers are starting to plant cacao trees in small areas within the rain forest ecosystem, trying to provide a more natural environment in which the pollinators can thrive.6 Also, hand pollination can be used to supplement poor natural pollination.
If you enjoyed this story, you may want to read Vanilla Without the Bee and The Dying Honeybee
- Young, Allen. M. The Chocolate Tree, A Natural History of Cacao. Gainsville: University Press of Florida, 2007. 3.
- BioBulletin. "The Chocolate Tree." http://www.amnh.org/education/resources/rfl/web/bulletins/bio/biobulletin/story720.html
- Young, Allen. M. The Chocolate Tree, A Natural History of Cacao. Gainsville: University Press of Florida, 2007. 116.
- Ibid. 134.
- Ibid. 161.
- BioBulletin. "The Chocolate Tree." http://www.amnh.org/education/resources/rfl/web/bulletins/bio/biobulletin/story688.html