Acaricide, Fungicide and Drug Interactions in Honey Bees

[AmericasBeekeeper]

Chemical analysis shows that honey bees (Apis mellifera) and hive products contain many pesticides derived from various sources. The most abundant pesticides are acaricides applied by beekeepers to control Varroa destructor. Beekeepers also apply antimicrobial drugs to control bacterial and microsporidial diseases. Fungicides may enter the hive when applied to nearby flowering crops. Acaricides, antimicrobial drugs and fungicides are not highly toxic to bees alone, but in combination there is potential for heightened toxicity due to interactive effects. The effectiveness of tau-fluvalinate [9] and coumaphos [10] has waned as Varroa populations have developed resistance to these acaricides. There are also documented interactions between the sterol biosynthesis inhibiting (SBI) fungicides and pyrethroid insecticides in honey bees [20]–[22]. The different acaricides varied greatly in their propensity for interaction with other compounds. Tau-fluvalinate interacted with most other compounds tested, including all 5 acaricides, 8 of 9 fungicides or a fungicide combination, and 2 of 3 antimicrobial compounds. Thymol interacted with 3 of 5 acaricides, 2 of 5 fungicides and none of the 3 antimicrobials.
http://www.plosone.org/article/info%...l.pone.0054092

[Andrew Dewey]

Thank you for posting the link. I have read the abstract and will get to the full study later.

My immediate take away is that the "hard" mite treatments can have unintended consequences in the hive. Is that your conclusion as well?

I have been advised by my State Apiarist that mites in my area have developed resistance to the active ingredients in Apistan and Checkmite, so those products were crossed off my list of possible mite remedies long ago.

[Kieck]

Really neat and much needed study, I think. Unfortunately, anyone who doesn't read all the way through it might draw some skewed conclusions here.

First, the study was looking at interactions of chemicals. That is, the effects of acaricide 1 are known, and the effects of acaricide 2 are known, but the effects of acaricide 1 plus acaricide 2 may be different than just the effects of acaricide 1 and the effects of acaricide 2.

And, this paper concedes very early on that, "Chemical analysis of honey bees (Apis mellifera) and hive products show that most managed bee colonies in North America and Europe are repositories of a suite of chemical contaminants, including an assortment of insecticides, acaricides, herbicides and fungicides."

The researchers included thymol and oxalic acid in their protocol, too, which produced some interesting interactions with groups of chemicals in their tests.

The unintended consequences, I think, come from using more than one treatment and experiencing interactions between or among those chemicals, not simply from using one class or type of pesticide.

[deknow]

The unintended consequences, I think, come from using more than one treatment and experiencing interactions between or among those chemicals, not simply from using one class or type of pesticide.

1. I'm not aware that any of the treatments intended for use in the hive have any warning or label instructions against using them alongside other treatments...in short, these interactions between beekeeper treatments occur when being used properly, according to the label.

2. "Tau-fluvalinate interacted with most other compounds tested, including all 5 acaricides, 8 of 9 fungicides or a fungicide combination, and 2 of 3 antimicrobial compounds."

....the fungicides are not in the hive because the beekeeper put them there, or used them. Interactions with fungicides come from using one thing, and having environmental exposure to others.

3. There is no advise offered to beekeepers not to use mite treatments and antibiotics at the same time...again, these effects occur when all the treatments are being used properly.

deknow

[Kieck]

1. I'm not aware that any of the treatments intended for use in the hive have any warning or label instructions against using them alongside other treatments...in short, these interactions between beekeeper treatments occur when being used properly, according to the label. -deknow

Sure. That's why this study was much needed. Determining interactions of chemicals in cases like this is vital, I think.

However, not to bring too much argument into this thread, but no label exists in this country for oxalic acid in beehives. It isn't registered with the EPA as a pesticide, so far as I know.

....the fungicides are not in the hive because the beekeeper put them there, or used them. Interactions with fungicides come from using one thing, and having environmental exposure to others. -deknow

Without quoting the post in this thread, my comment about "unintended consequences" was in response to the comment about this study revealing that "hard" treatments have "unintended consequences" in hives. Those consequences, I think, come from unanticipated interactions with other chemicals in hives. Simply making a single application of a "hard" chemical may have some "unintended consequences." The interactions are not likely to occur unless other chemicals are present as well. That seems to me to be the purpose of the study, not a simple condemnation of "hard" chemicals.

Also, it deserves notice again that some of the chemicals in the study are not generally considered "hard" in previous threads here on Beesource. Those "soft" chemicals can also produce unintended consequences if/when they interact with other chemicals.

There is no advise offered to beekeepers not to use mite treatments and antibiotics at the same time...again, these effects occur when all the treatments are being used properly. -deknow

And perhaps from research like the work reported in this paper, such advice will be posted on labels in the future.

[AmericasBeekeeper]

Andrew, you are correct from this study of interactions and other studies of the diminishing effects of current treatments.
Kieck, the study is all about the cocktails in the hive that are lethal to bees, especially some viewed as "natural" or soft.
Chemical producers are not currently required to test likely lethal combinations. That is changing due to studies by Dr. Ellis ath the University of Florida.
Besides chemicals the beekeeper pours in the hive, foragers bring in, there are also residuals on used equipment and treatments to extend the life of the woodenware. For instance Copper Tox, copper napthalate, or whatever that green preservative sells as does not kill bees by itself, but when combined with chemicals in the study, there were consequences in Florida research at least.

[Kieck]

I think I already got that, AmericasBeekeeper. What seemed to be misleading in the first response was the emphasis on "hard." The study included both "hard" and "soft" chemicals and found potentially lethal interactions when using either "hard" or "soft" chemical treatments.

A more accurate summarized conclusion might be, "Mite treatments can interact to cause unintended consequences."

[Barry]

But surely this has been known for quite awhile now?