• Dona Stewart

Wild and Honeybees in the Vineyard: What is the Difference?

Bees are not needed to produce grapes; wind alone is enough to pollinate the hermaphroditic vines. But there is growing awareness of the mutual benefits between vineyards and bees.

Clearing land for agriculture, to include vineyard development, is strongly linked to declines in the wild bee population. Wild or native bees, such as Bumblebees (genus Bombus), lose their ground nesting sites and access to floral resources that provide pollen. Round and fuzzy, with improbably short wings, there are over 250 species of these bees. They are found in all major wine making regions and can be an important vineyard management tool. By cultivating differing types of plants viticulturists can regulate key soil nutrients, including nitrogen, as well as break down and stabilize soil. Both grasses, which deplete nitrogen and nitrogen fixers, such as legumes, depend on bees for pollination.

The Benefits of Wild Bees

Some vineyards now intentionally create flower rich-habitats to support wild bees and other beneficial predator insects. Sunflowers, which increase bees’ resistance to disease and parasites, as well as provide great visual appeal for guests. Lavender, often planted in biodynamic vineyards, both support wild bees and provide a protective border or early alert for pests such as sharpshooter leafhoppers that spread Pierce’s disease. This bacterial disease (X. fastidiosa) is a major threat to the US wine industry and can now be found in Europe. With no known cure, it kills the vine by cutting off its water conducting vessels.

Management of vineyard inter-rows, the area between the vine rows, can promote wild bee resilience. Evidence from Europe (Kratschmer et al) found increased wild bee diversity and abundance in vineyards that adopted extensive inter-row management practices. Such practices including planting of floral resources, low till practices and less frequent disturbance of vegetation in the inter-rows. The reduction or elimination of herbicides is also believed to benefit wild bee populations.

Climate change is a threat to wild bee populations. An increasing number of unusually hot days are associated with rising extinction rates and a steep reduction in the number of colonies among Bumblebees since the mid 20th century. Soroye (et al) found the probability of site occupancy declined by 46% between 2000-2014 in North America, compared to baseline data from 1901-1974. In Europe, the probability decreased 17%.

But What about Honeybees?

Honeybees (Apis mellifera L.) are also pollinators and many orchards and vineyards have introduced hives on their properties. These domesticated bees are highly valued for their honey production. Indeed, commercial beekeeping has expanded greatly in recent decades. In the US there are an estimated 2.8 million colonies up from 1.4 million in 1969. Each colony houses an average of 30,000 bees.

Unfortunately, the presence of high-density honeybee colonies can harm wild bee populations. Research in France found the occurrence of wild bees decreases significantly with closeness to honeybee hives. Competition for floral resources is increased, which can trigger an aggressive response from the wild bees. While honeybees tend to use a wide variety of floral resources, native bees often specialize on particular plants, there is no alternative source. Honeybees can displace or ‘competitively exclude’ foraging wild bees by depleting an available resource. This competition between managed and honeybees also results in reduced nectar and harvesting by the honeybees (Henri and Rodet).

Does this mean there is no role for managed honeybees in vineyards? No. But viticulturists and apiarists need to work collaboratively to successfully manage the shared floral resources in and around vineyards.

For the research articles mentioned here see the Climate Research section of our website.

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