Written collaboratively by Adam Varenhorst, Patrick Wagner, Amanda Bachmann, Ruth Beck and Mackenzie Mattern.
Anyone scouting sunflowers would find it hard to miss the abundance of bees and other beneficial insects that are present on the sunflower heads during flowering. Flowering also marks a time when insecticides are applied to protect sunflower yields from insect pests. Since the sunflower is native to North America, there are numerous pests which can impact it. These include the red sunflower seed weevil, banded sunflower moth, sunflower moth, and numerous other pests. 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 evening hours.
Importance of Pollinators to Sunflower
The sunflower varieties grown in the U.S. were bred for self-fertility. However, there is evidence that both honeybees and native wild bees can improve pollination.
Sunflowers are visited by honeybees as well as many 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
In South Dakota, the most abundant pollinators in sunflower fields are native bees. The most observed bees included Melissodes trinodis and Lasioglossum spp. These bees don’t have common names but are known to visit sunflowers.
There are also many other species of bees that visit sunflower during flowering (Figure 1, Figure 2, and Figure 3-A). Although in limited numbers, honeybees have also been observed (Figure 3-B).
