bees in the news diseases wild bees and native bees

Pollen can carry disease to native bees

While studying pesticides in pollen, I was always curious about the potential for pollen to carry disease organisms as well. Indeed, a new study that appeared in the December 22 PLoS ONE confirmed my worst fears—that pollen may be a major route of viral infection from managed honey bees to wild native bees.

The authors of the study examined the four viruses that are most commonly found in North American honey bees—deformed-wing virus, sacbrood virus, black queen cell virus, and Kashmir bee virus—plus Israeli acute paralysis virus, which is often found in conjunction with colony collapse disorder. They asked a number of questions about bee-to-bee disease transmission and then set up a series of experiments to answer those questions.

They found eleven species of wild pollinators in Pennsylvania, New York, and Illinois that carried at least some of the viruses. These viruses were much more likely to show up in wild pollinators that lived near apiaries known to be infected with the various pathogens.

Tests on both the pollen and the bees themselves showed that in many cases disease-free foragers were carrying pollen loads that contained viral diseases—especially deformed-wing virus and sacbrood virus. This finding indicates that the pollen, itself, may be capable of transmitting the disease from one bee to another—it may not be necessary for an infected bee to pass the virus directly to another bee. Similar to human viruses that survive on door knobs, these bee viruses appear to survive on pollen grains.

In other experiments, honey bees and bumble bees kept in greenhouses were shown to transmit Israeli acute paralysis virus among themselves by simply foraging on the same flowers. The disease moved freely in both directions, from honey bees to bumble bees and from bumble bees to honey bees.

The authors point out that the exact mechanisms of disease transmission via flowers and pollen are not understood and more study is needed to see if host plants have a greater role in disease transmission than just as physical carriers. In the meantime, it is important for beekeepers to understand the impact diseased honey bees may have on wild pollinator populations. Honey bee health needs to be a priority if we are to maintain the health—or perhaps the very existence—of wild pollinator populations.

For more information, you can download the complete paper for free at


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  • I’ve always been curious about the lead content in pollen. I live in an urban neighbourhood, sort of half way between the suburbs and the downtown area of a small city. Behind my house is a 300 foot field full of wild grass and flowers. But the soil back there, which I had tested because I considered growing some veggies in it, contains something like 400 parts per million of lead. Almost anything I grow in that soil would pick up the lead. So no veggies for me.

    But what about the flowers? My honeybees are collecting pollen from flowers in a lead-filled field all summer long. Does the lead make it into the flowers, then the pollen, then the honeybees and then the honey?

    I wonder about that.

    • Phillip,

      I forwarded this question on to a professor I know who specializes in plant roots and nutrient uptake. I don’t know if the lead will stay in the vegetative part of the plant or move into the pollen. Good question.

  • Hey Rusty,

    I guess you haven’t heard anything about flowers taking up lead from soil? I Google the topic once in a while. It doesn’t seem to be a topic of concern, even among urban beekeeping organizations who probably should be concerned.

    Leaded soil in urban environments is not uncommon. If vegetables grown in leaded soil can’t be consumed safely, then what makes the pollen and nectar from flowers growing in leaded soil safe?

    • Phillip,

      On the contrary, I have several articles that I’ve found over the past year. Both nectar and pollen accumulate lead as well as other heavy metals and non-metals including selenium, from the soil. I haven’t written the post because I’ve been swamped with other projects, but I always feel guilty about it because I know you are waiting on an answer. But the short answer is yes, definitely.

  • No problem, Rusty. Although the news about the lead does kind of stink. I’ll have to get our honey tested for lead and other nasties before I give any more away.

    • No, Phillip, wait. It’s not bad as all that. I’m writing the post right now and will have it up today.

  • Hello,

    I am beekeeper a and used to buy bee pollen powder from China to my country Iraq for the last 3 year. Last order, I buy 6 ton packed each 1 kg in a sealed bag.

    The problem that I face this time is some bag I use, it destroy the hive with in few hour.

    Can any one help me? And if it is a bacterial or viral or chemical agent? And what to do? And how to know that?

    Please any information my help me.


    • If this is true, it is the most disturbing story I’ve heard in a while. There is no way I can diagnose the problem, but my opinion is that you need to dump all six tons right now. And dump it in a safe way–you don’t want to contaminate water, soil, or air with it. Treat it like hazardous waste.

  • Hey Rusty much appreciate the info you post. I let my bees clean the supers after spinning. I eliminate diseased hives but often the supers are loaded with new frames. Will these frames (honey no pollen) transfer disease to the cleaner bees?

    • Robert,

      The disease most often transferred in honey is American foulbrood. So if you don’t have that in your apiary, there won’t be a problem.