New Means of Varroa Control: Liebig-Dispenser

Thursday 27 October 2022

In this week’s blog, we are returning to our review of new Varroa mite control products! Using up-to-date and new products can improve your ability to control pests and disease in your apiary.  This also supports an integrated pest management (IPM) approach, as one important aspect of IPM is to apply different forms of pest control. This includes employing a variety of different chemical treatments, rather than relying on a single product. In beekeeping, oxalic acid and formic acid are two popular treatment options. Last week we discussed the new Varrox EDDY vaporizer, used to dispense oxalic acid. Today, we will overview our experience in using the Liebig-Dispenser to apply formic acid to a Varroa-infested honey bee colony.

New Means of Varroa Control: Liebig-Dispenser

The Liebig-Dispenser is a new device from Andermatt BioVet which facilitates the release of formic acid. Formic acid is an organic acid treatment used against Varroa mites. It is a liquid which evaporates into the hive and kills phoretic and developing mites. The Liebig-Dispenser is a low-tech product that comes with clear instructions for use. Furthermore, there is an informative video on the Andermatt webpage. These instructions are critical because the application differs based on the weather, the type of hive being treated, and the concentration of formic acid being applied. 

Contents of the Liebig-Dispenser kit. There is a bottle with measurement lines, a cap for transport, and a special insert for slow release of formic acid. Once filled, this is placed over a paper-wick which sits on top of a plastic base. The bottle and base are reusable, but the paper-wick is single use. (ATTTA©2022)

To use the Liebig-Dispenser, formic acid is first placed in a small plastic bottle which is to be inverted over a paper-wick. Prior to inverting the bottle, the paper-wick must be adjusted to the proper size. The wick, itself, has printed guidance and perforated lines to help with sizing. The ability to adapt the dosage rate with these adjustments is one advantage of the Liebig-Dispenser over traditional pads. The applicator clearly indicates how to adjust the wick according to temperature, offering three potential ranges. This reenforces the importance of using the proper dosage in consideration of ambient temperature when using a formic acid treatment.  The ambient temperature is aligned with the style and size of the hive being used to determine how to adjust the wick. Warre hives, Langstroth, and Dadant style hives are just a few of the options laid out, making use of this applicator accessible to many styles of beekeeping. Even considering all of these options, the instructions are concise and easy to follow. The kit also accommodates the use of either 60% or 85% formic acid. The paper-wick is double sided, such that instructions for using 60% are on one side and 85% on the other. Having an adjustable paper-wick for the slow release of formic acid is an advantage of the Liebig-dispenser as this ensures that evaporation will occur as effectively as possible, given the condition of your specific colony. 

After safely filling the plastic bottle to the appropriate level, the bottle is inverted over the paper-wick for a slow release of formic acid into the hive. The apparatus is placed on the top bars of the uppermost chamber and remains within the hive until the bottle is empty and the paper is saturated, at which point treatment is complete. The special bottle makes measuring simple and enables a precise treatment, however a drawback is that it takes up space in the hive. To accommodate the height of the bottle, a rim or empty super must be placed on top of the brood chamber. After about a week, when the bottle is empty, the equipment should be removed from the hive. The uncertainty around when the bottle will be empty is a slight disadvantage to this kit, as well. For example, the instructions indicate a treatment range of 3-7 days, but if you return to remove the bottle and it is not empty you must delay removal and return again. Nonetheless, at this point in beekeeping, a follow-up trip to the hive for cleanup is unavoidable in formic acid treatments, as all products require manual removal. Depending on your mite-levels after this first treatment, a second treatment might be necessary with this product. Instructions for such a case are laid out on the paper-wick. For safety, wear proper personal protective wear including a face mask, eyewear, and chemical grade gloves.

Liebig-Dispenser filled with formic acid and placed on the top bars of a Langstroth hive. (ATTTA©2022)

Overall, our experience in using the Liebig-Dispenser was positive. It is low-tech and low-impact, as only the used paper-wick needs to be disposed of after an individual treatment. In terms of effort, the most significant disadvantage of using this product over other formic acid dispensers is the additional space and equipment needed to accommodate the size of the bottle. Outside of function, another obstacle in using this product is that the Liebig-Dispenser is not yet sold by beekeeping distributors in our region.   As such, there is additional effort and expense in obtaining it. If you are interested in trying this applicator, reach out to your local beekeeping supply store.

Thank you to Andermatt BioVet for allowing ATTTA to test these new products! They were pleasant to work with and facilitate simple Varroa mite treatment options for Maritime beekeepers. As per good IPM, remember to test your hives again after treatment!

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