AMES, Iowa – This week is Pollinator Week, and when it comes to bees, you may be surprised to learn there are a few more species than honeybees or bumblebees. In the U.S. alone, scientists have discovered more than 3,500 different species.
“We all benefit from pollinators,” says Assistant Professor Dr. Matt O’Neal with the Department of Entomology at Iowa State University. The benefits, he says, are present in both wild and cultivated plants. “This might sound a bit strange to farmers in Iowa because as you know, corn is wind pollinated and soybeans are bred to be self pollinated.”
But O’Neal says a growing body of scientific literature, in particular research out of Brazil, suggests that wild bees alone can improve yields modestly, by between six or eight percent.
“But when honeybees are brought next to soybean field, yield improvements are estimated at around 26 percent,” says O’Neal. In a practical sense, encouraging bees to forage within a soybean field involves establishing plants at the edge of a given field in order to attract them.
Beyond attracting them, O’Neal says producers can protect pollinators like wild bees one of two ways. The first is straightforward: decreasing bee exposurce to insecticides. ISU Extension recommends reducing dust from treated seeds during planting and applying insecticides when crops are not flowering as just two ways to limit bee exposure. Producers can also check out the IDALS Sensitive Crops Directory to locate beehives near their farms.
The second form of protection is by increasing the presence of bee habitat, and that’s where the right mix of native flowering plants at the edge of a field can bloom year-round and provide constant forage for pollinators.
At ISU’s Horticulture Research Station, O’Neal stands flanked by a small soybean field to the west and a small melon path to the east. He explains that melons require pollinators into order to grow; soybeans, as previously mentioned, can self-pollinate.
Between the two fields is a plot of five different plants: swamp milkweed (Asclepias incarnata), pinnate coneflower (Ratibida pinnata), cup plant (Silphium perfoliatum), New England aster (Symphiotrichum nova-angliae), and meadow zizia (Zizia aurea). O’Neal describes them as the five plants bees find most attractive, but says other research at ISU is an examination of different plants native to Iowa’s prairies, which together remain in bloom throughout the spring and summer. The result for bees is a year-long buffet that encourages them to remain in the area, and to pollinate the nearby melon and soybean fields.
It’s difficult to quantify how interested the average farmer might be in pollinator health. But O’Neal says planting a mix of native plants to encourage the presence of pollinators can piggyback on other conservation measures a producer might already be taking to protect his or her bottom line.
“The benefit of prairie can be seen at multiple levels,” says O’Neal, pointing to the plot of 5 plants at his feet. “So, if this was placed strategically, say at the base of a water shed, it can act as a barrier to nutrient runoff and soil erosion. A group of scientists at Iowa State University are working on what’s called the STRIPs project ; it’s exploring how you can strategically place prairie to get multiple benefits. Not just biodiversity, [and] not just beneficial insects, but also to reduce soil erosion and reduce nutrient runoff.”
Research at Michigan State University has found nine flowering plants and three grasses which together attract the most pollinators and beneficial insects, such as natural predators of common pests. In order of bloom period from early to late, the eight flowering plants are Canadian anemone (Anemone canadensis), meadow zizia (Zizia aurea), pinnate coneflower (Ratibida pinnata), swamp milkweed (Asclepias incarnata), common boneset (Eupatorium perfoliatum), cup plant (Silphium perfoliatum), prairie ironweed (Vernonia fasciculata), New England aster (Symphiotrichum nova-angliae) and smooth blue aster (Symphotrichum laeve). The three grasses are Canada wildrye (Elymus canadensis), switchgrass (Panicum virgatum) and little bluestem (Schizachyrium scoparium).