April 2011 //
Vol. 29 // No. 2
Jan 4, 2011
Wheat as a cover crop in Iowa protects soil from erosion and builds soil quality. A hidden benefit may be reduced nitrous oxide emissions from fertilized farm fields. Nitrous oxide is a much more potent greenhouse gas than carbon dioxide.
Photo courtesy of USDA
Better pollination can mean higher yields for crops, sometimes nearly three-fold.
Photo courtesy of USDA NRCS
// SUSTAINABILITY //
Pollinators Increase Profit, Decrease Risks
Variety of Native Bees Serves Producers Across U.S.
By Edith Munro, for the Native Pollinator Project

Growers looking for conservation practices that improve their bottom line are finding that establishing habitat to promote native pollinators pays off almost immediately in crop after crop.
 
Plant-Incorporated Protectants May Help Protect Pollinators
 
By Steven L. Levine, Ph.D, Monsanto Corporation

Declines in native and managed pollinators have led to an increased focus and global dialogue on the potential factors that may contribute to these declines. There is also an increasing emphasis on the role of wild bees in agro-ecosystems among conservation agencies. 
 
Monsanto, along with other agricultural companies, academics, and government agencies, has been actively involved to expand the framework to assess the potential effects of crop protection products on honey bees and native pollinators. 
 
These groups have been working together to identify the individual and combinations of stressors that are most strongly associated with pollinator declines. Recently, a panel of international experts from academia, industry and government agencies has been working together with the goal to provide additional recommendations for evaluating potential risk to insect pollinators from pesticides in a reliable and cost effective way.

Along with scientific endeavors to enhance pollinator protection, adoption of genetically modified crops that produce plant-incorporated protectants (PIPs) has allowed farmers to plant crops that require significantly less use of broad spectrum pesticides. 
 
Many pest insect species have complicated life cycles and may only live outside of the plant and be susceptible to sprayed insecticides for a short period of time. This short window of susceptibility is difficult to predict and could require multiple applications of insecticides to catch pests vulnerable at the start, middle, and end of that window. 
 
Crops that produce PIPs are highly specific against the targeted pests. This high level of specificity for the target pests greatly benefits native pollinator populations. Through 2009, it was reported that commercialization and adoption of PIPs resulted in a cumulative reduction of 393 million kg of what are considered to be broad spectrum pesticide active ingredients. 

To gain domestic approval for crops producing PIPs, the U.S. EPA requires an battery of ecological safety studies on beneficial insects that includes honey bees. Results from a combined analysis of honey bee studies published in the journal PLoS ONE (Duan et al. 2008), found that crops that produce PIPs and are commercialized for control of lepidopteran and coleopteran pests do not negatively affect the survival of either honey bee larvae or adults in laboratory settings. 
 
The results from these scientific studies are reflected in grower’s reports from the field; that beneficial insects, including native pollinators, are on the rise in fields with crops that produce PIPs.  
 
This is good for pollinators, good for agro-ecosystems, and good for American farmers, who have contributed for more than a decade to the sustainability of agriculture through the use of genetically modified crops that produce PIPs.
“I would say with quite a bit of confidence that there are benefits to farmers,” says Rudy Rice, chairman of the Native Pollinator in Agriculture Work Group and past president of the National Association of Conservation Districts.

“In my many years of working with farmers to install conservation practices, i have learned that the biggest obstacles have been high installation costs and no near-term economic returns. Establishing pollinator habitat is an easier sell because it is a low-cost practice with positive near-term net returns.”

Beans and Bees

"If you look at the older literature, when the USDA (U.S. Department of Agriculture) had the Wisconsin bee laboratory, they could show in some years and certain locations that you could get an increase in yield," says Dr. Reid Palmer, USDA's Agricultural Research Service (ARS) research geneticist and collaborating professor in the Department of Agronomy at lowa State University. More recently, Palmer has heard second-hand reports of farmers who saw soybean yields improve in fields adjacent to crops where their pollinator promotion efforts had increased bee numbers.


In Canada, a short-term study found the presence of bees was associated with much higher yields in food-grade soybeans. In Australia, researchers have demonstrated a yield increases of l0 to 40 percent in honeybee-pollinated soybeans, compared to naturally self-pollinated beans.

Another line of research to address is the differences among soybean varieties' ability to attract bees. Palmer remarks, "We would use the differences in insect-pollination attraction rates to develop high-yielding and low-yielding breeding lines. These lines should provide clues to the soybean traits that contribute to pollinator attraction. We have been able to produce highly insect-pollinator attractive soybean lines within as little as three years."
 
"Soybeans naturally drop a lot of flowers and not from lack of fertilization," says Palmer. "Even now, plants usually produce many more flowers than develop into pods, so if you can reduce flower drop, you should increase yield. We really need to study the role of bees in soybean pollination."
 
The problem of preserving bees while controlling insect pests is another major issue. Palmer notes, for example, that areas around Plainview, Tex., where chemical use has been very limited, have huge numbers of native ground dwelling bees that love soybeans. "We need to understand much better what's going on between bees and soybeans," adds Joseph.

Challenges for Iowa

For Iowa, promoting bees can be especially difficult for several reasons. The primary benefit is typically better pollination and higher yields, although the level of improvement varies from crop to crop. One of the best examples is cherry tomatoes, where native bees can nearly triple output. Even in crops commonly thought of as self-pollinating, there are indications that bees may deliver benefits, for instance by improving pod set in soybeans.

The soybean's ability to self pollinate has meant a bit less worry for Iowa's 42,000 soybean growers. There are hints, however, that it may be worthwhile to take a closer look at insect pollination, including the role of native bees, in soybean production. Of interest especially is the possibility that under the right conditions, bees could help boost soybean yields. Several studies have shown that insects working soybean flowers improve pod set.

Last year, Iowa lost 74 percent of its honeybees, more than double the national average, according to Andy Joseph, state apiarist. Several factors are at work, from diseases like Colony Collapse Disorder to a shortage of flowering plants that can provide nectar throughout the growing season, and the challenges of controlling major insect problems like soybean aphids without damaging bee populations.
 

"The problem of preserving bees while controlling insect pests is another major issue. Palmer notes, for example, that areas around Plainview, Tex., where chemical use has been very limited, have huge numbers of native ground-dwelling bees that love soybeans. "We need to understand much better what's going on between bees and soybeans," adds Joseph.

A ditch without riparian plants and trees provides no native pollinator habitat.

Photo courtesy of Darlene Robbins
 
Same ditch viewed from other side of road (ditch flows under road crossing). Riparian area has been populated with vegetation attracting native pollinators.

Photo courtesy of Darlene Robbin

Enough Pollinators to Make a Difference?

In the meantime, concerns over bee losses prompted Congress to make native bee preservation a priority in the 2008 Farm Bill, leading the USDA to establish multiple programs to encourage bee habitat. One example is the matching grants and technical assistance available through the Environmental Quality Incentives Program (EQIP).

Encouraging native pollinators is also now a ranking criterion that can mean higher payments per acre for new Conservation Reserve Program contracts. As a result, farmers established 41,000 acres of new pollinator habitat this year, according to the Xerces Society.

Success in the West

Beyond their effect on yield, native bees often deliver secondary benefits.

Claire Kremen, a researcher at the University of California Berkeley, notes that the same habitat that encourages native bee species also typically supports other beneficial insects that prey on crop pests like aphids.

In Walla Walla County, Washington, alfalfa seed producer Tim Wagoner reports saving big bucks on pollination costs because of the native alkali bees.

“Most people outside the valley use leaf cutter bees,” says Wagoner. “They take a lot of management [and] they’re very expensive. We buy two gallons of leaf cutter bees per acre as a back-up, but without the alkali bees, we’d be buying four, five, or six gallons per acre.”

He estimates that his alkali bees cost him about $5,000 per year, compared to leaf cutter bees, which can cost up to $100,000. “On one field without leaf cutter bees, we got over 1,200 pounds of production per acre totally pollinated by native alkali bees,” he reports. “They give us a huge advantage – better yields than anyone in the world as far as I know.”

As concerns about the availability and cost of rented honey bees prompt more growers to look at the value of native pollinators, the challenge lies in the details of adapting a pollinator program to different crops, each within specific agronomic conditions and individual farm practices.

“We’ve gotten a really positive response from almost every farmer we’ve approached about establishing pollinator habitat,” reports Jessa Guisse, California pollinator outreach coordinator for the Xerces Society.
 
“My sense is that a lot of people want these projects but need some assistance when they get into the details of planning a habitat that fits within their farm,” she says.

Extensive research is now under way to determine which pollinator-friendly plants are best suited to different regions and crops. Other studies are aimed at answering another question that varies from crop to crop: Just how much can native pollinators benefit the farmer in dollars and cents?

What’s already clear is that pollinator habitat doesn’t necessarily mean a loss of production acres. On many farms, it can be incorporated with other conservation efforts into field margins, filter strips, windbreaks, or other areas not suited for planting.

The good news is that improved, easier-to-use information to customize a pollinator program is becoming increasingly available.

Growers looking for information about encouraging native bee habitats can contact the Natural Resources Conservation Service or find online information at the Native Pollinators in Agriculture Work Group (www.agpollinators.org), the Xerces Society (www.xerces.org/Pollinator) or in USDA publications at (www.nrcs.usda.gov/technical/ECS/database/technotes.html).

About the author: Edith Munro Communications is based in Windsor Heights, IA.