Now the last honey must be harvested immediately. We refer you to the last info letter. However, please be absolutely sure that when honey combs are removed from the brood chambers of the production colonies, or even from the young colonies, sufficient honey reserves remain (at least two completely capped combs). In some cases, the colonies are very strong and absolutely need these reserves. If you take too much honey from the bees now, you risk that if immediate replacement feeding does not follow, the colonies will starve. Also make sure to complete the honey harvest in the early morning hours to avoid robbing.
Once the honey is harvested, chemical varroa control must be carried out: As you know, for successful beekeeping it is necessary that the varroa infestation be reduced as much as possible before the rearing of winter bees and reach an absolutely low level (=starting population) with the beginning of brood rearing in the following year. In terms of timing, we are now already in the second phase of varroa reduction. The first phase consisted of regular cutting out of drone brood during the season and removal of varroa mites from the production colonies through the creation of young colonies. Only now – after the last honey harvest – may chemical varroacides be used. Varroa control is completed with the winter treatment.
The motto applies: Whoever does not now skim off the first batch of existing mites must reckon with poorly developed winter bees. This significantly increases the danger of winter losses of entire colonies. It is also important to carry out treatment as simultaneously as possible across the area. This can protect against untreated colonies distributing their mites to previously treated neighboring apiaries. When colonies collapse due to varroosis, as is known, most mites are distributed beforehand via flying bees or through robbing to neighboring colonies. This objective of treatment as comprehensive as possible across the area is also pursued in some places through an official animal disease authority general order. 2 / 3 We definitely recommend carrying out early chemical control this year. Perhaps in this way the varroa pressure, regardless of the infestation of the individual apiary and individual colony, can be reduced overall across the area.
How can treatment be done now? The bee colonies are in brood, so in Lower Saxony essentially one varroacide is suitable – 60% formic acid (FA) ad us. Vet.. This FA can be obtained through the district veterinarian. 85% FA has not been approved to date. Only in some federal states can the veterinary authority approve the use of 85% FA for a limited time due to a treatment emergency. This does not apply to Lower Saxony. The use of 85% FA is, moreover, more suitable for the cold season when 60% FA loses its effectiveness. Lactic acid (15% ad us. Vet.) can also be used now. However, this does not reach the mites in capped brood and so the treatment must definitely be repeated. Thymol-containing products are apparently not sufficiently effective in this region. Oxalic acid cannot be sufficiently effective at this time of year since the bees cluster tightly together and the colonies must be brood-free. Its application is therefore not advisable at this time.
Treatment with 60% formic acid (FA) – Short-term treatment We basically recommend the application of FA via the sponge cloth as a short-term treatment. Certainly there are experienced beekeepers who work successfully with long-term evaporator systems. However, since 85% formic acid may not be used in Lower Saxony, only short-term treatment via sponge cloth remains.
- If possible, cooled 60% formic acid. 2 ml FA per bee-covered DNM/Zander frame
- Outside temperature: between 12 – 25 °C. If daytime temperatures exceed 25 °C, apply formic acid in the evening. The weather forecast should be noted, as treatment should not be carried out during thunderstorms, rain, or high humidity. These treatments are ineffective due to moisture-related dilution of the FA.
- Sponge cloth approximately 20 x 20 x 0.5 cm, apply the acid with a dosing instrument (measuring cup or syringe) only in the middle. To do this, place the sponge cloth beforehand on an acid-resistant base (e.g., plate or plastic bowl) outside the bee colony so that the FA does not drip into the bee colony.
- Before placing the sponge cloth, push back the bees with smoke puffs and remove any wax residue on the top bars with the hive tool,
- Then place the sponge cloth with the formic acid as close as possible to the bee cluster (at the top) and seal it with plastic film against the hive roof
- Any existing hive mesh floors must be covered, but the entrance must absolutely be completely open!
- With light varroa infestation, at least 1 application before feeding, followed by 2 further FA treatments after feeding.
- With heavy varroa infestation, 2 applications before and 2 applications after feeding. The time interval between two successive treatments should be approximately 3 to 5 days. In doing so, do not reuse the previously used sponge cloth. The already used sponge cloth has too much residual moisture for a follow-up treatment. Let the used sponge cloths dry thoroughly first.
- after each treatment (after approximately 24 hours) remove the sponge cloths from the colonies immediately, otherwise the bees will glue and gnaw them.
- Then begin winter feeding immediately.
Please also observe safety requirements when handling organic acids. Organic acids are caustic!
Further details can be found on our homepage at: http://www.laves.niedersachsen.de/live/live.php?navigation_id=20139&article_id=73963&_psmand=23
Dr. Otto Boecking BZB Guido Eich BZB Wulf-Ingo Lau
Lower Saxony State Office for Consumer Protection and Food Safety Institute for Apiculture Celle – Secretary Herzogin-Eleonore-Allee 5 D-29221 Celle 05141-90503-40 (Telephone) 05141-90503-44 (Fax) kathrin.halanke@laves.niedersachsen.de www.laves.niedersachsen.de