At least a third of the crops humans rely on for food are pollinated by insects, birds and bats. The pollen of zucchinis and many other
vegetable and fruit flowers rely on the escort services of pollinators to facilitate egg fertilizations. Native and domestic bees are the best known pollinators, commanding world-wide attention for their reduced survivability.
The rusty patched bumble bee, for example, is an important pollinator of zucchinis, tomatoes, wildflowers and other species, and they are now endangered. Domestic honey bees, for another example, are important pollinators of alfalfa, apples, cucumbers and other species; in 2016 there were 124,000 bee colonies pollinating flowers and producing honey in Minnesota. Honey bees are not endangered, though they require more management to continue their diligent work.
Shirley and Delmas Hines of Hines’ Gardens are beekeepers who have managed bees for over a decade near Princeton: “My husband, son and I are beekeepers,” said Shirley Hines. She summarized their recent honey production: “Last year was our best year. The hives did really well – we had about 500 pounds taken from 17-20 hives. We’ve had honey until now for sale at farmers’ markets and events.“ The Hines have set-up one hive on their farm, two at Prairie Restorations Inc, and another fifteen at a blueberry and apple orchard near Princeton.
Throughout the US, honeybee colonies have struggled to survive, especially through winters when they need a heavy store of honey, pollen, and to be healthy. The Hines’ colonies need to survive whatever a Minnesota winter offers, as well. Hines said, “Hives usually don’t survive. This year, we had about two hives survive.” Hines did not speculate on the reasons for losing hives. “Here we have ag fields across the road, and the bees have flowers on the trees at the orchard, and flowering plants along the rum river.”
Since 2006, US and European beekeepers have sustained hive losses averaging 30 percent per year. A mysterious loss of bee colonies termed “colony-collapse-disorder” has prompted speculation and research implicating microbes, mites, stress, pesticides, and habitat loss.
In 2013, the European Union placed a moratorium on a class of insecticides, neonicotinoids, suspected of contributing to the colony disorder. Recently, a large study in the European Union, involving three countries, also pointed a finger at neonicotinoids for possibly reducing the reproductive status of bee colonies.
About three years ago there were news reports in the US about neonicotinoids on many nursery plants, including flowers for pollinators. The irony of selling flowers containing a suspect in the collapse of bee colonies was exposed to consumers who demanded pollinator-friendly plants. Since then, most nurseries have eliminated neonicotinoids from most flowers and have identified plants with neonicotinoid applications.
Robert Koch, a University of Minnesota professor and extension entomologist, works on insect problems in soybeans. He said the colony-collapse-disorder may be a compound problem involving a combination of influences, including habitat loss, disease and pesticides.
Koch elaborated, “There are people with a negative impression of neonicotinoids. The neonicotinoids and some other pesticides are one piece of the puzzle of the bee problems.” These interacting pieces can lead to collapse of the colony. If important pieces are intact, the colony may thrive. “If bees have flowers, they are more likely to survive,” he said.
The European study had a similar assessment after showing bees were affected by neonicotinoid exposure on farms in the UK and Hungary, but were not affected in Germany where bees had more wildflowers where they could forage near their hives. Researchers thought the bees in Germany may have been healthier with more diverse flowers and may have avoided direct exposure from neonicotinoid-contaminated crop flowers.
In Minnesota, where corn and soybeans dominate the crop acreage, the exposure of bees may be different. Phil Glogoza, an extension educator for the University of Minnesota at Moorhead, explained: “There’s a body of evidence that contaminated dust during planting time has been shown to affect bees in the corn belt, but it’s an engineering problem.” He said the problem is caused when the pesticide particles blow away from the seed onto hives and bees. The problem can be solved by engineering the pesticide to adhere to the seed or within the planter. He continued, “Corn and soybeans are not exposing bees through pollen and nectar. Let’s find out where risks are being generated and address them (with proper information).”
Koch said a common product used as a seed treatment in soybeans is “Thimethoxam,” produced by the syngenta corporation. A more widely used product is “Imidacloprid,” produced by the Bayer corporation, and it is used on ash trees to treat the emarald ash borer, and on crops, gardens and yards.
Neonicotinoids are a class of insecticides developed in the 1980s as a safer alternative to other classes, like organophosphates, according to Koch. “Neonicotinoids became popular because they were less toxic to humans and the environment. They are very effective when pests are present. If there are plants being attacked by some soil-dwelling pests, it’s too late to apply an insecticide. Seed treatments will protect plants when these types of pests attack. Seed applied neonicotinoids do a good job on wire worms and white grubs (which cannot be controlled with foliar sprays of insecticides). Seed applied treatments provide protection for a certain time; if aphids come in early, the seed treatment may be helpful. If the aphids come later, the farmer will likely have to treat the field with a foliar insecticide. There are alternatives to seed treatments that have their own set of risks. If farmers use alternatives, they may use organophosphates. Studies have shown orgnophosphates are a problem (due to toxicity) for humans” Koch explained.
Glogoza added, “(Neonicotinoid) products will provide protection from soil pests, but beauty is systemic (action of neonicotinoids) protect young plants early in establishment. There are reasons to use seed treatments. In other situations, when farmers take an insurance approach (using insecticide in case there’s a pest infestation), there may be an alternative to neonicotinoids. I’ll ask a farmer what the problem is and ‘will treatment justify use?’ Is there a risk which may not be necessary to take.”
The quest is on to understand pollinators and to be sure they continue facilitating a large portion of common foods. If garden zucchinis do not attract a pollinator at flowering time, gardeners can intervene and escort pollen from the anther to the stigma, but this may not be necessary as researchers and beekeepers close in on the causes of colony-collapse-disorder. The effects can possibly be reduced with more abundant and diverse wild flowers, and by engineering the pesticide to adhere to corn and soybean seeds rather than blowing as dust.