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Range of challenges impacting crop pollinators




  • CHICAGO — Pollinators are facing a range of challenges.

     

    “There are 20,000 plus species of bees,” said Iain Kelly, bee health issue manager for Bayer CropScience. “Honey bees are the most versatile — they will survive from the tip of South America up to Canada.”

    Honey bees are not native to the U.S. They came to this country about 1622, said Kelly during a presentation at the American Seed Trade Association’s CSS 2013 and Seed Expo.

    “Bees contribute from 9.5 to 10 percent of the economic value of the global food supply,” he reported.

    “Some crops get a really nice yield bump with honey bee pollination, but are not totally dependent on them,” Kelly said. “However, almonds are totally dependent on bees. Without bees the yield is negligible.”

    Pollination by bees is important to the production of fruits, nuts and vegetables.

    “As we see the world population change and diets changing in developing countries, they will need more pollinators and more bees,” Kelly said.

    Bees’ Role Changes

    The bee industry has changed over the years.

    “There were about 6 million colonies in the U.S. during World War II, when people raised bees because sugar was in short supply,” Kelly said. “The industry has changed from hive products and producing honey to pollination services.”

    A significant portion of the bee colonies are used for almond production.

    “Of the 2.6 million bee colonies in the country, 1.6 million are used to pollinate almonds every spring from mid-February to mid-March,” Kelly said.

    These colonies are then moved around the country.

    “Some colonies go all the way up the East Coast and some up the West Coast,” Kelly said. “Although honey bees are really adaptable species, there are some challenges due to the opportunity for transferring diseases with that kind of movement.”

    Kelly listed a number of factors affecting bee health, including parasites, especially the Varroa mite.

    “A USDA/EPA report on bee health recognized the Varroa mite as the single most detrimental pest of honey bees,” he said. “It attaches to the bee and the real problem is the mite transfers viral diseases.”

    Greater collaboration and information sharing among stakeholders would facilitate best management practices and that is critical to improving honey bee health, Kelly said.

    “In late February, the USDA is bringing together experts on Varroa mite control,” he noted. “Industry has looked at ways to kill a bug on a bug. It’s not easy, but by working collaboratively maybe we can find a model that will be beneficial.”

    Weather and nutritional deficiencies also affect bee health.

    “North Dakota gets about half a million colonies, and with the changes in CRP land there, beekeepers are not finding it as easy to summer their bees and build the hive strength up for the following year,” Kelly explained.

    “Pesticides and the misuse outside of the hive are clearly an issue,” he said. “And there are queen issues — the queens are not surviving as long and beekeepers have to replace them more often.”

    Causes Of Bee Loss

    Beekeepers are not talking as much about Colony Collapse Disorder as they have in the past, Kelly said.

    “It’s not in the top 5 of losses identified by beekeepers,” he said.

    “Starvation is very high on their list from incomplete diets due to forage resources,” he noted.

    Seed treatments have changed from seed borne prior to the 1980s to insecticides that protect plant establishment, provide nematode protection to now application technology.

    Neonicotinoid seed treatments are used on about 150 million acres of row crops each year.

    “The benefits of neonicotinoid seed treatments are a positive effect on plant health and vigor. They help plants get established. We use fewer sprays at lower application rates and there is targeted application,” Kelly said. “Overall, there is really a big benefit with these products over older chemistry.”

    When looking at the risk with seed treatments, Kelly said, it is not toxicity or exposure that provides a risk it is putting the two together.

    “A risk equals the hazard or toxicity times the exposure,” he said.

    Plants have two systemic pathways — the xylem moves water and the phloem moves sugars.

    “Neonicotinoids don’t move well in the phloem,” Kelly said. “When we measure residues in the pollen and nectar, we’re seeing very low residues.”

    Bee mortality around corn planting is an issue the industry is working on.

    “Incidents compared to acres planted have been quite small, but we need to work to minimize exposure,” Kelly said. “And equipment manufacturers are looking at designs to minimize the dust.”

    Bee health is going to improve if three things come together — science-based risk management for pesticides, stewardship and an investment in bee health, Kelly said.

    “Lab data doesn’t always relate to field situations,” he noted. “Many times we’ve seen compounds look great in the lab, they really control disease or insects and they just don’t work in the environment. We have to know how to relate lab studies to field studies.”

    Honey bees are not on the verge of extinction, Kelly stressed.

    “We need a good supply of bees,” he said. “This is an issue that we need to work on as a group to resolve the dust problem.”

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