Anyone who lives in, or has visited the Western Cape, will marvel at the vista of vineyards from coast to coast and inland; abundant and lush; our farmers with a keen eye on keeping a healthy ecosystem for honey bees and other pollinators.
As you may know grapes are self-pollinating, so why bees in a vineyard?
Simply, bees visiting the lands mean the flowers are worthy of the trip and good for them and it shows that an ecosystem is healthy, which means healthy vines for great wine.
This is not to say that honey bees don’t sample nectar juices from aging grapes that have burst with dripping juices, which is honey eagerly made in their honey stomach for their stores for winter. And it stands to reason that what is planted in and around the vineyard has a key role to play in healthy vines.
Many farmers are moving into creating more organic and sustainable vineyards which use cover crops to compete out weeds (not all of them just the one’s you don’t need), offer organic matter (and nutrients) for better soil quality and to cut back erosion.
These attract not just honey bees but all the other pollinators who share their joy for pollen and nectar, and of course with them comes the natural predators who create a wonderful balance offering a level of integrated pest management. In fact in many vineyards one might find Runner Ducks who spend their days eating vineyard snails and other vine pests, a valuable introduced ‘predator’ to the IPM mix.
What are our honey bees really getting up to on the vines?
A study from South Australia indicates that honey bees are deliberately removing the calyptra* from grapevine flowers.
*Definition of calyptra : a hoodlike structure in a plant especially.
In layman’s terms the calyptra is made of 5 shell like petals that fuse into a unified enclosed structure protecting the flower parts. They are removing this during the flowering phase, increasing pollen by 72% versus after the capfall. Clever honey bees. But there is more to it.
Reading the research paper, one can’t help but become totally fascinated because grape flowers are not attractive to honey bees, they are hidden or inaccessible – so there is something more driving them to find flowers before capfall and deliberately remove the calyptra to get at the pollen.
One suggestion is this calyptra, this hood, releases sesquiterpenes at the moment it opens under pressure, just before capfall. (Martin et al. 2009)
If you know a little of natural science you will know this terpene to be one of many naturally occurring compounds in plants and some animals, and its possible that this terpene attracts the bees to loose caps; with the sesquiterpenes playing multiple ecological roles.
Two mentioned in the study are a role in the chemical communication in bees (Leonhardt 2010), and in defence against pathogens – and in pollinator attraction (Huang et al. 2012).
This deliberate cap removal by honey bees benefits the development of berries and grape bunches. So while we don’t traditionally associate honey bees with grapes and vineyards in their traditional pollination role, they are clearly playing a key role on the vines for the end product.
“The removal of caps by honey bees could be important in several ways. For example, caps that fall from the flowers but are retained in the bunches can be sources of Botrytis infections later in the growing season (Nair et al. 1988). In addition, cap removal by honey bees could be important for varieties where persistence of the calyptra has consequences for fertilisation and consequent development of the fruit. One such variety is Pinot Noir, where the occurrence of millerandage has been associated with failure of caps to fall (Friend et al. 2003), and persistence of the calyptra causes the formation of live green ovaries (Heazlewood and Wilson 2004). Other varieties that potentially suffer from this phenomenon are Merlot and Shiraz. However, in these varieties, the importance of cap retention for the development of millerandage has not as yet been established.”
Cap Removal By Honey Bees Leads To Higher Pollen Rewards From Grapevine Flowers Katja Hogendoorn, Kay Anantanawat, Cassandra Collins Read the full research report here
Can honey bees damage your berries?
No. They don’t bite them, they visit if there is a crack from natural splitting, bird punctures or other insect visits that leave an opening.
We are planting Trees for Bees
Through our reforestation and integrated biodiversity projects we are supporting healthy biodiversity corridors and playing a role in mitigating climate change impacts, programs that are part of our commitment to the UN Decade on Ecosystem Restoration as an official supporter.ABOUT OUR BOLAND TREES FOR BEES PROJECTS