OXUVAR ® Natural winter treatment April 2007

2 Contents 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

3 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

4 Active substance : oxalic acid Discovered in 1769 in Common wood sorrel Nature identical substance Present in many plants as rhubarb, spinach, tea, cocoa, etc. Natural component of honey Source :

5 Oxalic acid in honey Honey typeNatural concentration of oxalic acid (mg/kg honey) Heath Honey from honeydew (oak) Thyme42-83 Polyfloral honey14-50 Lavender11-46 Rosemary15-23 (Nozal et al. 2003)

6 Use of oxalic acid Bleaching agent Mordant (coloration of textiles) Wood restoration Removal of rust stains Varroacide

7 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

8 Varroacide Used since the second part of the eighties in the Eastern Europe Highly acidic (pH < 1) : toxic for Varroa Accepted for biological control according to EU-regulation no. 1804/1999

9 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

10 OXUVAR ® 10

11 OXUVAR ® Water-sucrose (1:1) with oxalic acid dihydrate (3.5% m/V) Efficacy exceeding 95% (as shown in numerous scientific trials) Solution freshly made! → no toxic degradation products for bees (HMF)! Controlled quality Advantageous price 11

12 Formation of HMF Formation of HMF (Hydromethylfurfural) in a watery solution of oxalic acid with sucrose : (Bogdanov et al. 2001) mg HMF/kg solution Room temperature in darkness Room temperature at daylight weeks

13 Warning Oxalic acid solution is dangerous! Harmful in contact with skin and if swallowed Wear chemical resistant gloves and safety glasses!

14 Preparation of OXUVAR ® At first put on the glasses and the gloves! Warm up the oxalic acid solution in a hand-hot water bath Open the bag of sucrose with scissors Open the can

15 Preparation of OXUVAR ® Transfer all the sucrose powder into the plastic bottle Screw the lid on tightly and shake the bottle very well to dissolve all the sucrose Apply hand-warm

16 Application of OXUVAR ® In November-December Colonies broodless (ca. 3 weeks after the first frost) Air temperature > 3° C Determine where the winter cluster is situated through examination of the sticky board Trickle the oxalic acid solution in the occupied aisles For two storey hives, lift the second deep and trickle on the first deep

17 Dosage of OXUVAR ® Draw on with syringe : 30 ml weak 40 ml for the middle colonies 50 ml strong → 5-6 ml per aisle 17 A mixture is enough to treat 10 to 15 colonies (500 ml). Mite fall will continue for at least three weeks!

18 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

19 Trials in Switzerland Efficacy [%] (Charrière et al. 2002) n=7n=8 n=6 n=10

20 1.Oxalic acid 2.Varroacide 3.Preparation and application of OXUVAR ® 4.Trials in Switzerland 5.Incidence on bees and residues?

21 Incidences on bees Oxalic acid is well tolerated by bees : The next spring the treated colonies will be as strong as non treated colonies!

22 Incidences on bees (Charrière et al. 2004) Development of colonies after different treatments (OA= Oxalic acid) (Switzerland) Bee losses No. of Bees ControlSpraying OATrickling OAPerizin ®

23 Residues No increase of oxalic acid content after a single treatment (Bogdanov et al. 2002) Oxalic acid content of honey varies naturally between 1 mg/kg et 800 mg/kg Honey of treated colonies showed a content from 5 to 289 mg/kg -> remains in the natural variability! (EMEA 2003) Wax does not absorb oxalic acid

24 Summary OXUVAR ® is : Allowed in organic beekeeping Effective Easy to use Harmless for bees Optimal for all hive’s products

25 Literature Bogdanov S., Kilchenmann V., Charrière J.-D., Imdorf A. (2001), Storage of Oxalic Acid Sucrose Solution, Swiss Institute for Bee research, Agroscope Liebefeld Posieux, Bern, ( ) Bogdanov S., Charrière J-D., Imdorf A., Kilchenmann V., Fluri P. (2002), Determination of residues in honey after treatments with formic and oxalic acid under field conditions, ( ) Charrière J.-D., Imdorf A. (2002), Oxalic acid treatment by trickling against Varroa destructor : recommendations for use in central Europe and under temperate climate conditions, Bee world 83 (2): ( ) Charrière J.-D, Imdorf A., Kuhn R. (2004), Bienenverträglichkeit der verschiedenen Winterbehandlungsmethoden gegen Varroa, Agroscope Liebefeld Posieux, schweizerisches Zentrum für Bienenforschung, Bern, ( ) EMEA (2003): The European Agency for the Evaluation of Medicinal Products Veterinary Medicine and Inspections, Oxalic acid, summary report, London, ( ) Nanetti A., Stradi G. (1997), Oxalsäure-Zuckerlösung zur Varroabekämpfung, allg. Dt Imkerzeitung 11, 9-11 Nozal M. J., Bernal J. L., Gomez L.A., Higes M., Meana A. (2003), Determination of oxalic acid and other organic acids in honey and in some anatomic structures of bees, Apidologie 34, , ( )

Thank you for your attention!