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Time to Spray Sunflowers: Don’t Forget About the Pollinators

Originally Submitted: August 5, 2022

As sunflowers in South Dakota begin to reach the flowering stages, it is important to remember that, in addition to insect pests, there are also pollinators visiting these flowers. These pollinator species are hard to miss, as they are often sharing the same areas of the sunflower head as sunflower insect pests. Since sunflower is native to North America, there are numerous pests that can negatively impact it, which include the red sunflower seed weevil, banded sunflower moth, sunflower moth and several others. Although insecticides are often necessary to reduce pest populations and prevent yield loss, it is important to consider the impact that they may have on beneficial insects like pollinators.

The best time to spray insecticides on sunflowers, to avoid direct contact with pollinators, is during the early morning or later afternoon/evening hours. Although some of these products may deter bee visitation, it is important to remember that broad spectrum insecticides negatively affect all insects that are exposed to them.

Importance of pollinators to sunflower

The sunflower varieties grown in the United States were bred for self-fertility, but there is evidence that both honeybees and native wild bees can improve pollination. Sunflowers are visited by honeybees, as well as numerous species of native wild bees. For both confection and oilseed varieties, research has demonstrated that pollinator activity can improve yields.

What we’ve observed so far

Green bee on yellow flower.
Figure 1. Bright, green, metallic, native, wild bee, Agapostemon virescens, visiting sunflower. Courtesy: Adam Varenhorst

In South Dakota, the most-abundant pollinators in sunflower fields are native bees. The most-observed species include Melissodes trinodis and Lasioglossum spp. These bees don’t have common names, but are known to visit sunflowers. There were also many other species of bees that visit sunflower during flowering (Figure 1, Figure 2, Figure 3).

Like in other pollinator studies, honeybees were also observed, but were not captured in great abundance. There is often confusion between identifying honeybees and M. trinodis due to similarities in size and coloration. It’s important to remember that honeybees will have hair present on their eyes, whereas the other observed species won’t.

Brown bees on yellow flower.
Figure 2. Native wild bees pollinating sunflower. Courtesy: Adam Varenhorst

 

Black and yellow bee on yellow flower.
Figure 3. Bumble bee visiting sunflower. Courtesy: Adam Varenhorst

 

Related Topics

Sunflower, Pollinators