Bees in beans: Q&A with Matt O'Neal
Dr. Matt O'Neal, an Iowa State University entomologist, has focused his research mainly on developing insect pest management programs for soybean production.
In studying soybean aphids, and being aware of the crisis in U.S. pollinator populations, O'Neal has taken an interest in the role of honeybees and native bees in Midwest crops. He spoke at the Bayer Bee Conference in Ames, Iowa, last spring, telling attendees that bees appear to play a big role in pollinating soybeans, and that more native bees are being found in crop fields than ever expected.
I followed up with an interview of him this summer in preparing a Successful Farming magazine story on pollinators -- bees and the other creatures upon which so much of food production depends. His comments provide a fascinating perspective on the current condition of pollinators in corn and soybean landscapes, and offer some ideas on how farmers can help bee populations thrive.
Walter: I’m working on a story on the pollinator situation, particularly as this current crisis pertains to production agriculture. Is there any new research that would be of interest to farmers?
O'Neal: There is quite a lot of research going on at ISU related to bee health, conservation, and pest management. I am aware of at least four research groups that are exploring these topics. My work involves studying the pollinators that visit corn and soybean fields and best practices for conserving them. One project that we are working on is the occurrence of bee viruses in the many bees (both honeybees and native, solitary bees) of Iowa. We are exploring if the landscape in Iowa influences the occurrence of these viruses.
My lab is exploring the pollinator community that visits corn and soybean fields. Although this sounds simple, it has been remarkably interesting. This project is entering its third year, and we have found over 20 species of bees that visit both crops.
Combined with the species of flies that can also pollinate plants, we have over two dozen species. This is a surprise to me, as during the past 10 years of studying insects in soybeans, I rarely found bees. However, what we have learned is that the way you sample insects in these fields determines what you find. Using a net is not good enough to capture these many species. We needed to use traps that mimic flowers, both in color and shape, to capture bees in these fields.
In a separate project we are exploring the best ways to conserve beneficial insects, especially those that help suppress pests and pollinate crops. These insects need food and shelter when annual crops are not present. We have found that a mix of native, perennial plants that provide flowers throughout the season can increase the abundance and diversity of these beneficial insects. We have just begun a project to determine if a mix of these plants can increase the abundance and diversity of beneficial insects to an adjacent vegetable or soybean crop.
Walter: What best practices would you recommend for farmers to reduce the negative effects of row crop production on pollinators?
O'Neal: The recent USDA/EPA joint report on the health of honeybees in the U.S. noted that several factors are contributing to their decline. These factors included declining honeybee genetic diversity, loss of high-quality forage, exposure to invasive pests (especially the varroa mite), diseases, and pesticides.
Several of these factors are out of the control of farmers, but there are a few that farmers can influence. One is the loss of forage habitat; the other is the use of pesticides. Farmers who are interested in improving habitat for pollinators could consider modifying non-cropland within their control. There are federal programs through the Environmental Quality Incentives Program (EQIP) by the USDA that can help support such improvements to CRP land. These improvements include planting native flowering forbs into existing CRP or new land.
Farmers who use pesticides, including insecticides applied to seed and foliage, are required by law to follow the instructions on the label. These instructions include activities to reduce the exposure of honeybees and other bees to insecticides, like not applying during bloom period of the crop.
Within Iowa, there is a registry of honeybee hives in the state. Farmers who are applying insecticides within 1 to 2 miles (I think) of a hive are required to contact the owner so that the hive can be managed in a way that will reduce exposure to insecticides. Also, the applicator is requested to spray during dusk, when bees are not actively foraging.
Finally, farmers can use an IPM-based approach to pest management to limit the use of insecticides. Applying insecticides only when needed, and using other approaches (crop rotation, insect-resistant crops, etc.) can reduce the use of insecticides and their impact on pollinators. By mixing the tactics, farmers also reduce the risk of insect pests developing resistance to any one tactic.
Walter: Given the decline of honeybees, do native bees have a role in the effort to shore up pollinator populations? Is habitat creation a useful technique in Midwest agriculture, do you think?
O'Neal: This is a difficult question as there is limited information on the impact of native bees for many of the crops grown in the Midwest. However, this information base is increasing. For example, native bees have been discovered that do a better job of pollinating cucurbit crops than honeybees.
But honeybees are still the dominant source of crop pollination, pollinating an estimated $8 to 14 billion in crops per year. Native bees are estimated to pollinate one third of that. With the decline in honeybees, there is an interest in increasing the abundance and impact of native bees. One way to do that is through the creation of the habitat that these native bees need to survive in our Midwest landscape.
From our research we have observed a remarkably diverse community of native bees that can be found in Iowa. Most of these are solitary bees that make nests in the ground. A few are stem-nesters; they need above-ground nesting material found in old or decaying wood. In addition to providing nesting habitat so these insects can survive the winters, they also require flowers when crops are not available.
For example, several bees use corn and, to some extent, soybeans for pollen and nectar, respectively. But these crops are only present for a brief period. During spring and fall, native plants can provide bees forage. The flowering forbs found in prairie are a very attractive source of forage for native bees.
Walter: In your presentation at the Bayer Bee Care tour, you talked about the role of bees in soybean growth. What do we know, in brief, about this phenomenon? Do bees help boost soybean yields?
O'Neal: There is limited evidence that when soybeans are exposed to bees (most of the evidence is for honeybees) soybean yields are increased in a range of 10% to 30%. This is a bit shocking as soybeans are self-fertilized very quickly in the lifetime of the flowers. Furthermore, we do not find a lot of honeybees in soybean fields, yet many beekeepers report that the honey made by them is mostly from nectar collected from soybeans.
Since native bees make up the majority of the bees we find in soybean fields, we are trying to quantify this phenomenon with the native bee community of Iowa. Efforts to study this phenomenon are challenging, as it requires getting the timing of the field studies just right.
Currently we are identifying which of the over 20 species of bees found in soybean fields are most often found with soybean pollen. It will be what we focus on in the future.
More information: For details on conservation of beneficial insects, including bees, visit the Leopold Center for Sustainable Ag’s website:
The website includes a two-page factsheet with details about the plants recommended for conserving beneficial insects.
The site also includes a link to a larger document that reports on the research on beneficial insects.