Institute of Northern Ireland Beekeepers Using Formic & Oxalic Acids for treatment of Varroa & Tracheal & Honey bee parasitic mites Michael Young Institute of Northern Ireland Beekeepers

Occurs naturally in plants Oxalic acid in nature Occurs naturally in plants Carrots contain 500 mg/kg Broccoli contains 900 mg/kg Rhubarb leaves Occurs naturally in insects.

Oxalic acid in honey Natural constituent of honey Values range between 8 and 300 mg/kg in honey Moist vegetables contain much more OA than honey Low risk of residues in honey. Bernardini and Gardi 2001

Oxalic acid use in Europe Recently registered (2005) and extensively used in Europe Maximum residue limits established Dec. 2004 at 50 millequivalents of free acids If used according to European recommendations, there is no risk of problems with honey. Rademacher and Imdorf 2004

Methods of application Oxalic acid is applied by spraying, trickling or evaporating Trickling is the preferred application in Europe Effectiveness greater than 90% Mechanism of acaricidal action has not been investigated in detail. Rademacher and Imdorf 2004

Trickle method Trickling a solution of water-sugar-oxalic acid is a promising method to keep Varroa levels down. 100 parts water and 100 parts sugar by weight 75 g Oxalic-1 liter water- 1 kg sugar will make 1,66 liter solution that is enough for 50 hives. This mixed up solution will keep for a few weeks only and should be used at once. Use 20 to 35 ml solution for each hive depending on the size of the treated colony. Trickling a solution of water-sugar-oxalic acid is a promising method to keep Varroa levels down. It has to be done late in the season when there is no brood in the hive. A large syringe makes it easy to control the volume given to each hive. It is much faster, safer, and cheaper than using a vaporiser. Use only Oxalic-2-hydrate (C2H2O2*2H2O), not the waterfree Oxalic. Mix 7,5 parts Oxalic to 100 parts water and 100 parts sugar by weight 75 g Oxalic-1 liter water- 1 kg sugar will make 1,66 liter solution that is enough for 50 hives. This mixed up solution will keep for a few weeks only and should be used at once. Use 20 to 35 ml solution for each hive depending on the size of the treated colony.

Easy Access                                                   On a 2 box hive the solution is distributed according to the amount of bees in each box. The top box normally holds more bees and is given 70% of the solution The bottom box is given 30% of the total solution.

(5-6ml between each frame) The solution is distributed evenly in the gap between the top bars, so it will drip down and reach as many bees as possible. (5-6ml between each frame) Time per hive 1,5 min.

Spray Method Not necessary to remove individual frames Spray top and bottom cluster Quick and effective.

Vaporizers Russian Gas Battery 12volt Each hive receives uncontrolled amount of oxalic acid. Oxalic acid contains approx 50% water that mean the first few colonies get only steam and the following colonies high concentrated acid. Two grams acid per hive is the right amount to kill Varroa mites. It is not possible to control the dosage with this Vaporizer, an over dosage oxalic acid will shorten the live of  honeybees dramatically. Vaporizer JB 200 Electric  for 12volt car battery connection. The JB 200 is ideal for commercial beekeepers. Several Vaporizers can be connected together on a battery to treat more than one hive at the time. Vaporizer JB 600   easy to use from the entrance of the beehive. No heat in the hives and no problems with hives from Styrofoam. Easy portability - only requires propane torch.

Efficiency from the Oxalic Acid evaporation in a different dosage Test result Without treatment water Oxalic Acid evaporation (g/Beehive   0,5g       1,0g    2,0g     3,0g 5,0g Lowest effect 0,0% 1,3% 51,7% 93,2% 91,7% 98,1% 99,0% Average effect 1,2% 4,8% 82,8% 96,0% 97,2% 99,2% Highest effect 2,7% 11,5% 99,6% 99,7% 99,8% Beehives per test 6   8   12   10   13   11   5

European Guidelines Make a solution by dissolving 35g OA in 1 liter of lukewarm solution sugar water (1:1 solution) Recommended dose is 5-6 ml per occupied frame space Treat in Autumn or early winter Most effective in broodles colonies Treat when temperature. Is 32-55°F Wear glves and safety goggles

The physical properties of oxalic acid may be of interest in this connection. The stuff one buys is usually oxalic acid dihydrate, which is a crystal which has two water molecules attached to each oxalic acid molecule. The CRC Handbook of Chemistry and Physics gives the following properties for oxalic acid dihydrate: On heating: 1) The water of hydration leaves at 101.5 degrees C. The water boils off leaving anhydrous oxalic acid crystals. 2) At 157 degrees C the oxalic acid starts to sublime (goes directly from solid to gas) 3) At 189 degrees C the oxalic acid which has not yet sublimed decomposes to formic acid and carbon monoxide.

Treatment Considerations Mix fresh Store unused material in refridgerator Safety equipment Trickle Acid resistant gloves Goggles Spray or fumigation As above as well as Acid rated respiratory cartridge

Results Spray treatment reduces varroa infestation by 92% when compared to untreated (mean) Trickle treatment reduced varroa infestation by 87% Effectiveness of spray and trickle treatments are not significantly different

No Oxalic Acid resistant possible. It works by destroying the mite's suction ability, stopping it from feeding from the bee. Effectively, the mite starves to death.  

Essential advantages over the actual usually fighting methods are: no delays in the honey, beeswax and propolis very good bee compatibility  high degree of effectiveness , up to 99% in brood free colonies no early ageing of the bees (important to population of the bees in spring) outside any time of honey-collection usable very user kind for the beekeeper.

Caution:  Oxalic acid in its crystalline form is poisonous and should be handled carefully. It should not be allowed to contact the skin and it is essential that the dust is not inhaled Weigh and mix outdoors, preferably in a light breeze to take any dust away from you. In the solution given above it is safe to handle with rubber gloves.  Oxalic acid is not dangerous if precautions are taken. Wear rubber gloves and be careful not to let the acid touch your skin or eyes. Wear old clothes, use protective mask, and glasses.

Annual Bee meeting York Oxalic Acid can only be used by requiring a prescription from the vet It can only be used as a hive cleanser All beekeepers have to keep records of all medicines used as a treatment for bees If not! It carries a two year jail sentence

Thank You! Credits Dr Marion Ellis Nebraska University