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Plan bee

bee

As colony collapse continues
to plague American honeybee
colonies, MSU researchers
are calling up second-string
pollinators to help secure
the nation's food supply.

Honeybees have been the first choice of growers across the United States to pollinate crops and improve the quality of their yields for nearly four centuries. Imported from Europe in the early years of North American colonization, honeybees became a horticultural mainstay throughout the continent. And the economy depends on them. One example: American fruit growers—with honeybee-based pollination among their most prominent practices—have turned their collective products into an $18 billion national industry.

In 2005, however, the phenomenon known as colony collapse disorder began to afflict honeybee colonies across the country. Suddenly, some beekeepers lost up to one-third of their hives. This led to an increase in beehive rental fees for growers, costs that ultimately trickle down to consumers in the form of higher prices.

Researchers at Michigan State University, along with colleagues from 15 institutions throughout the country, are studying alternative pollination strategies, a sort of “crop insurance,” using less common bee varieties for growers hit hard by colony collapse. The endeavor, known as the Integrated Crop Pollination (ICP) project, is funded by the U.S. Department of Agriculture and is being led by MSU AgBioResearch entomologist Rufus Isaacs.

“This project is exploring other approaches to pollination,” says Isaacs, ICP principal investigator. “We’re trying to understand the options that growers have and measure just how effective those alternatives might be.”

Isaacs, MSU professor of entomology, has been investigating the contributions of wild bees and the effectiveness of managed non-honeybee species on blueberries for more than a decade.

Delving deeper into the subject, Isaacs began working increasingly on collaborative projects with researchers around the country. Many of the studies focused on determining the value of adding bee habitat areas to fields and orchards producing fruit crops.

“Then probably five years ago, the USDA’ Specialty Crop Research Initiative put out a call for proposals,” Isaacs says. “I started talking to some of my colleagues about how we might want to work on a project on fruit and vegetable pollination, specifically, about exploring combinations of elements for the best pollination in an economic and ecological sense.”

After a year of brainstorming, supported by a small planning grant, Isaacs and his colleagues refined their plan for ICP and were successful in gaining multiyear support for a national project. The team has now completed the first year of a five-year plan to explore the major factors that influence pollination. With Michigan as a top producer of blueberries, cherries and apples, the state is one of the primary fruit focus areas within the project.

Taking the census

MSU AgBioResearch scientists Larry Gut and Nikki Rothwell have been working together on ICP’s first objective: determining the size and diversity of pollinator populations. Their crews spent the past field season assessing the types of pollinators available, particularly for apple and cherry growers.

Native bees, those living in the wild, are an ever-present element, but their contribution to fruit pollination has not been fully documented in economic terms.

“We’re trying to quantify and qualify what's out there, in honeybees and native bees,” says Rothwell, coordinator for the MSU Northwest Michigan Horticulture Research Center near Traverse City, Michigan. “This project isn’t about replacing honeybees so much as it is about trying to find out what else is out there. If honeybees continue to have problems, we have to find out if native bees are a viable alternative.”

To this end, the researchers and their crews spent a few frantic weeks in the spring of 2013 estimating bee populations in cherry and apple orchards across the state. Initially, Rothwell focused solely on cherry and Gut on apple, but they quickly realized that there was a better approach.

“All this research has to be done while the trees are in bloom, which gives us a very short window to work within,” says Gut, a professor of entomology at MSU. “Nikki and I came to the realization that it would be a very good idea to join forces. Her crew came out to my sites, and mine went up to help her. The effort it takes to do this pollination research is pretty amazing. Bloom is such a short period of time, and because we had to wait for good weather, during that time every day counted.”

They employed two techniques to estimate bee populations. The first involved collecting bees with nets so they could take specimens back to the lab for identification and analysis. The second had technicians physically counting the bees observed in an area for a predetermined period of time to get an estimate of their numbers in the area. Collection and counts were conducted at various points within each orchard.

“We looked at the bees at four different distances from the orchard edge,” Rothwell says. “That way you get an idea of how far into an orchard the wild bees normally penetrate, and the relationship between the field and its surrounding environment.”

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Making habitats
blossom

Their second goal is to examine the relationship of bee habitats at the edges of fields compared to those within the fields themselves—like bee suburbs surrounding a city.

“The objective is to work with growers to plant wildflower strips beside orchards and look at how that enhancement of habitat for pollinators might enhance the number and kinds of pollinators in the orchard,” Gut says.

Adding a touch of the natural environment of pollinators into farms is not a new concept. Companion plantings, as they are also known, are used by growers to encourage pollination.

The work of ICP researchers is one of the first attempts to scientifically quantify the effects of such plantings on pollination and benefit for the grower. Although the value of such plantings remains a question yet to be addressed, Isaacs says.

“It could be that these plantings provide the extra habitat and nutrition needed to attract and maintain a healthy native pollinator presence in an orchard,” he says. “It could also turn out that the bees will be more inclined to visit the wildflowers rather than the fruit trees themselves. That’s why we need to do this measurement. We have to determine if companion plantings add significant value to a grower’s farm before we encourage growers to go through the expense of putting them in, and through this large project we can determine how this approach will compare across the nation.”

Expanding the demographics

Exploring the impact of other types of managed bees is another major objective. Honeybees have been the orthodox choice among growers for centuries, but other types of bees are available.

ICP project manager Keith Mason, a research assistant and graduate entomology student who's worked with Isaacs for 13 years, says bumblebees are another option that researchers are studying.

“Bumblebees, particularly in blueberries, can be a good choice because they do something called ‘buzz pollination,’ in which they vibrate the flower, shaking the pollen onto their bodies, which is then moved to the next flower,” he says. “That’s something honeybees can’t do. Bumblebees are also capable of flying in cooler temperatures than honeybees, which works out well in the cool springs we sometimes get in Michigan. Honeybees do have larger colonies, though, which can offset some of these disadvantages.”

But bumblebees are not the only bee species with possibilities.

“You also have what we call stem-nesting bees, many of which are in the genus Osmia,” Mason says. “In the wild, they build their nests in cavities in trees, but they can just as easily live in tubular housing that we provide for them at the field, such as bamboo stalks.”

The project will investigate the performance of bumblebees and Osmia bees over the coming years.

Worker buff-tailed bumblebee

Worker buff-tailed bumblebee
Photo by Alvesgaspar / CC BY-SA 3.0

Osmia bee at the entrance of nest

Osmia bee at the entrance of nest
Photo by Beatriz Moisset / CC BY-SA 3.0

Comparing pollinators,
maximizing yield

ICP researchers are combining all three of their objectives with the goal of helping growers maximize their crop yields in economically viable ways. To generate this information, the team identified fields around the country for a comparative study.

“We had to select farms that fit the criteria,” Isaacs says. “This project is being conducted in almond, apple, blueberry, cherry, pumpkin and watermelon, and we needed a consistent variety in each crop if possible, as well as fields of commercial size, five to 10 acres. We were also interested in the surrounding landscapes, so we tried to get a similar range of wild areas surrounding the sites.”

With the sites chosen and categorized, the team is measuring the type and number of pollinators, the number of visits that individual flowers receive and the total crop yield for each site to generate a better picture of the effects that various factors have on the biological and economic impact of pollination.

ICP researchers are also studying the effect of no pollination on fruit crops by excluding select branches of trees from contact with pollinators. Gut and Rothwell conducted some of these tests during the field season.

“We constructed chicken wire cages covered in bags around certain branches,” Rothwell says. “This keeps bees away and illustrates the effect of no pollination. It’s really stark to see how few fruits you get without pollination.”

After the data is analyzed this winter, the research team will begin to get a clearer picture of the best practices that fruit growers should use to keep their crops pollinated.

“A lot of times you can get great research results, but with methods that are not economically practical for growers,” Mason says. “We’re looking at the cost of investing in these different pollination strategies, as well as whether they will result in an increase in yield. Then, if they do generate an increase in yield, that obviously needs to offset the cost of putting these methods into practice.”

That is a question to be answered further down the line, however, as ICP is only in its first year of research.

“We’re in the lab right now,” Isaacs says. “The fruit we collected is being weighed and counted, the bees are being pinned and identified, and data is being entered. The results from this year will help us formulate what we do next year.”

Nikki Rothwell

Looking forward

Ultimately, the ICP team hopes to identify a variety of pollination options for growers.

“That’s what our project name means,” Mason says. “The idea is a lot like integrated pest management, where farmers have many options for managing pests and can choose the best combination of techniques to get the desired result.”

As researchers seek to better understand the implications of colony collapse disorder, the ICP team is striving to add more tools and knowledge to grower's arsenals. Over the next four years, they will test their hypotheses and help growers understand the relationship between their crops, their land and their bees. With growers armed with more knowledge and options, maladies such as colony collapse disorder could pose much less of a threat to the fruit, vegetable and nut industries that help keep Americans nourished.

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