New Varroa Control Chemicals

Pat Butler, Boulder County Beekeepers Association - March 9, 2004

2 chemical controls for Varroa destructor were recently approved by the EPA for use in CO

1. Api-Life Var ("essential" oils: thymol, eucalyptus, menthol & camphor)
   1. Fumigant - gradually released into hive via tablets
   2. Used in Europe for several years
   3. Canadian study (2001) compared Api-Life Var (ALV) to a pure thymol product and Apistan (fluvalinate) [mites there are not yet resistant to it] (American Bee Journal, June 2003, p. 489-493) [2 ALV tablets left in hive 6 weeks]
      1. Found comparable levels of varroa control
      2. though other research shows efficacy may be somewhat lower
      3. ALV safety to bees was comparable to that of Apistan
   4. Recently approved by EPA for use in CO via Section 18 (emergency) registration
      1. Available from Brushy Mountain Bee Farm (800-233-7929) [20 tablets to treat ~6 hives = $34]
      2. Requires:
         1. EPA Private Pesticide Applicator license (book and test available by calling Dick Loesch at EPA: 303-312-7283 or 800-227-8917 x 7283)
         2. CO Dept of Agriculture permit (available via phone by calling Ms. Curtis Phillips, 303-239-4144)
            1. CO Dept of Ag requires keeping records of pesticide use
   5. Use - READ LABEL!
      1. Wear waterproof gloves and eye protection (goggles or safety glasses)
      2. Apply only when average daily temperatures fall between 59 and 69 degrees F and when daytime temperatures do not exceed 90 F
         -- in Boulder Cty, this would be mid to late May into June and most of September
      3. Each application involves 1 tablet broken into pieces placed at each hive body corner (enclose tablet pieces in 8 mesh/inch wire screen)
      4. Replace tablet after 7-10 days twice (3 tablets total) and remove last tablet after 12 days [3 treatments should increase overall effectiveness]
      5. Remove tablet at least 30 days before harvesting
      6. DonŐt use during honey flow
      7. Can apply treatment no more than twice/year
   
   
2. Sucrocide (sucrose octanoate, sugar ester, i.e. fatty acid attached to sugar molecule, derived from plant leaves; approved food additive [emulsifier and stabilizer])
   1. Mode of effect: affects mite cuticle and/or respiration
   2. Used to control other ag. Pests like aphids, psyllids, spider mites
   3. WA State Univ. study (1999 -2001) of sucrose octanoate (SO) toxicity to bees and mites (American Bee Journal, December 2003, pgs 982-985)
      1. Found no bee toxicity at recommend treatment concentration (0.25%)
      2. 24 hr mite mortality averaged 68% (vs. 12% in control colonies)
   4. recently approved by EPA for full registration
      1. available from Dadant (877-432-3268) [1 pt treats ~ 29 hives = $20]
   5. Use:
      1. Wear eye protection while mixing and spraying
      2. Dilute 3 TBS Sucrocide in 2 gal. water and spray each side of all frames to cover bees and mites, approximately 2-3 passes of 1-2 seconds each (approx. 1 liter/20 frames of 1.5 oz total liquid/frame)
         1. must contact varroa directly to affect them
         2. to affect varroa in pupal cells, should apply 2d and 3rd application every 7-10 days
         3. bees will appear wet but will recover
      3. Does not accumulate in honey or wax and can be used during supering
      4. Can use this several times during season, as needed
      5. Sprayer must be calibrated carefully to avoid overtreatment (see Am. Bee Journal article for details)
      6. Researchers suggest avoiding treatment during very high or low temperatures
   
   
3. Economic Thresholds - a key feature of Integrated Pest Management (IPM)
   1. Before treating, be sure varroa meet or exceed economically damaging levels
   2. Can monitor varroa via sticky boards or sugar or ether roll techniques
   3. Thresholds vary by US region (i.e., higher in warmer climates)
      1. None developed exclusively for CO
      2. WA St. U. researchers threshold for treatment using (a) ether roll or (b) 48-hr natural mite fall: in April (a) 3 (b) 24, in August (a) 14 (b) 46, in October (a) 4 [no sticky board numbers for fall]
      3. Dr. Marion Ellis, U of Nebraska threshold for treatment using sugar roll: 36 in fall (unclear how this would translate to sticky-board natural mite fall) [sugar roll instructions: http://ianrpubs.unl.edu/insects/g1430htm]
      4. It would be useful to have CO-specific research to estimate thresholds
   
   
4. Overall comparison of ALV and SO
   1. Both offer alternative controls to Apistan and Check-Mite (coumaphos)
      1. ALV may have comparable effectiveness
      2. SO is probably less effective but can be used multiple times
   2. Both are somewhat more time-consuming than Apistan and Check-Mite
      1. ALV requires 3 tablets (in 3 applications) over the course of a month
      2. SO takes more time/application and also requires 3 applications over 20 day period
   3. ALV can be used only in fall, as a practical matter
   4. ALV requires EPA license and CO Dept of Ag. Permit and some record-keeping
   5. ALV can help to control tracheal mites
   6. ALV costs somewhat more ($5/hive vs. ~ $2/hive for S.O.)