IPM for Beekeepers: Managing Varroa Populations Landi Simone Essex County Beekeepers Society June 12, 2007
Review of IPM Principles • IPM means managing pest populations, not eradicating them. • Understand pest life cycle. • Monitoring is critical. • Know treatment thresholds. • Timing of treatments (when needed) is critical.
Varroa: Pest Identification • Small pin-head size 8-legged brown to reddish brown parasite sucks hemolymph from bees • Present in almost all U.S. colonies and in most countries LEFT UNTREATED, WILL CAUSE COLONY COLLAPSE WITHIN TWO YEARS.
Life Cycle of Varroa destructor • Adult female mite feeds on bees 5-13 days then enters brood cell 24 to 60 hours before capping. • Lays first egg 60 hours after capping, then every 30 hours thereafter • First mite to emerge is male. Subsequent mites are female, which mate with male and feed on pupa • Mature females emerge with bee; immatures and male remain in cell and die • Mites are transferred bee to bee in brood nest; prefer nurse bees for cell access
Effects of Varroa: Individual Bee • Workers • Life span reduced by 50% (especially bad for overwintering bees) • Food and wax glands damaged • Reduced disease resistance • Drones • Reduced sperm count • Less likely to mate successfully BAD QUEENS
Effects of Varroa: Colony Level • Pierced exoskeleton permits entry of multiple viruses normally present but dormant in the hive • PMS: Parasitic Mite Syndrome. Easily confused with foulbrood • Colony collapses under viral load, usually in late summer-fall
Seasonal Population Dynamics • Varroa is phoreticon adult bees in winter (ride + meal) • Breeds in brood come spring, esp. drone brood. • For every mite you see on a bee, there are two in the brood. • Populations peak in July and August
Monitoring Pest Levels: Powdered Sugar Roll • Add 400 bees (about 2 fingers) in a quart mason jar with hardware mesh screen on top • Add 1 Tbsp. powdered sugar & shake • Pour out sugar onto white paper • Count mites • Release bees
Monitoring Pest Levels: Sticky Boards • Easiest to use with a screened bottom board (SBB) but can be used without • Use commercial sticky board or use homemade tileboard or plastic smeared with petroleum jelly • Place below screen for 1 to 3 days • Count mites • Convert to equivalent 24 hour count
Determine Treatment Thresholds • At a minimum, sample from late July to mid-August: • 24-hour natural fall on sticky board: Take action if >50 mites • Powdered sugar roll: Take action if > 10 mites
Treatment Thresholds in Winter/Spring • Late Winter Sampling (early to mid-March) • 24 hour natural fall on sticky board: Take action if >2 mites • Spring Sampling (late March to mid-June) • 24 hour natural fall on sticky board: Take action if >10 mites • Powdered sugar roll: Take action if >3 mites
IF YOUR BEES NEED TREATMENT, GET IT ON BEFORE THE END OF AUGUST! Unless you’d rather have dead bees….
It bears repeating…. Don’t be a mutt! Treat your bees before August 31 or you won’t have bees next spring!
What about fall honey?? • How do I treat my hives and still get a fall crop? • How do I keep wax moths out of my supers in late summer and early fall without using chemicals?
One Beekeeper’s IPM Schedule • Start removing honey supers by August 15, one apiary at a time. • As you leave with the honey, slip sticky boards under hives’ screened bottom boards. • Extract honey. • Return 2 - 3 days later and count mites on sticky boards. • Determine which colonies need treatment.
IPM Schedule, cont’d. • Return extracted honey supers to original colonies, if possible, for bees to clean out for a few days. • When supers are dry, stack all dry supers on colonies not needing mite treatment. These hives will bring in a fall crop. • Treat colonies that need it. • Repeat for the next apiary. • In October, remove all supers for storage. Extract any fall honey the bees have collected.
Remove Varroa Treatments After the Specified Time Unless you want to lose more treatment options due to mite resistance….
Hard Chemical Treatment Options - “Smart Chemicals for Dumb Beekeepers” Dr. Medhat Nasr • Apistan (fluvalinate) • Pyrethroid • Low toxicity to beekeeper • Washighly effective (99%) in killing mites • Widespread resistance due to misuse. • Accumulates in beeswax. • Check-mite (coumaphos) • Organophosphate • High toxicity to beekeeper • Was highly effective (99%) in killing mites • Widespread resistance due to misuse. • Accumulates in honey and in beeswax. • May affect developing queens.
Hard Chemical Treatment Options, cont’d. • Amitraz • Amidine - affects nerve receptors • Relatively low toxicity to beekeeper; higher bee toxicity • Queens stop laying while in use. • Not licensed for use in the U.S. Not commercially available. • Some resistance reported in Europe. • Degrades quickly in honey and beeswax. • Fenpyroximate (Hivastan) *NEW* • Affects mitochondial electron transport • Toxicity to humans and bees similar to Amitraz. High toxicity to aquatic life. (Disposal issues.) • Accumulates in beeswax. • Not currently available under Section 18 in NJ, but NY has a Sec. 18. • The “hard” chemicals from least to most toxic: Apistan, Amitraz, Hivastan, Coumaphos
Fluvalinate Toxicity • NEWS FLASH!!! New research by Mary Ann Frasier at Penn State in 2008 indicates that Apistan (fluvalinate) is significantly more toxic to honey bees than previously thought. • PENN STATE RECOMMENDS AVOIDING APISTAN COMPLETELY.
Chemical Resistance • Mites which survive a chemical treatment due to a mutation live to parent subsequent generations, passing on the resistance gene. • Such mutations usually come with a down side - resistant mites do not reproduce as well as non-resistant mites if no chemical treatment is present. • Therefore, left untreated for a period, mite populations will often revert to a non-resistant state and chemical treatment will again become effective (though not at previous level.) • ROTATE TREATMENTS!
Testing for Resistance • Refer to USDA Beltsville Bee Research website: http://www.ars.usda.gov/Services/docs.htm?docid=7474 for detailed directions • Summary: • Staple a 3/8” x 1” piece of strip to be tested to a piece of index card and place in a wide mouth pint-size mason jar with screened lid cut to fit. • Collect 1/4 cup of bees from brood nest (not queen!) and add to jar. The hive must have >5 mites on an ether roll to do this test.
Testing for Resistance, cont’d. • Store jar at 86º F (30º C) for 6 hrs. • Invert jar 10 cm above a white piece of paper and hit base 3 times with your hand. • Count mites on paper. Call that # P. • Knock bees down, remove card with strip, add 1 cup of windshield washer fluid. Replace screen with solid lid. Shake 5 minutes. Replace screen & pour fluid onto filter cloth (e.g. nylon curtain fabric) held over a bucket. Add another cup of fluid, swirl and pour through again.
Testing for Resistance, cont’d. • Count the mites on the filter cloth. Call that number F. • The percentage of mites killed by the chemical tested is: P % Kill = X 100 (P + F) Note: If the total number of mites P + F is less than 5, The test is invalid. Pick another hive with more mites.
Hard Chemicals: Check-Mite • Plastic strips with chemical: Use one for every 5 frames of brood/bees (2 per deep brood box.) • 97-99+% efficacy if no resistance • Leave strips in 42 to 45 days, then REMOVE. • Honey supers must be off hives during treatment. Wait two weeks after treatment before supering. No temperature restrictions. • Neurotoxin. Wear chemical resistant nitrile gloves, NOT bee gloves. • Requires Pesticide Applicator License.
Hard Chemicals: Apistan • Plastic strips with chemical. Use one for every 5 frames of brood/bees (2 per deep brood box.) • 97 - 99%+ efficacy if no resistance • Temperatures should be at least 50º. • Leave in 42 to 56 days, then REMOVE. • Honey supers must be off hives during treatment. Wait two weeks after treatment before supering. • Wear latex gloves, not bee gloves.
Soft Chemical Treatment Options: “Dumb chemicals for Smart Beekeepers” Dr. Medhat Nasr • Thymol-Based: • Apilife Var • Apiguard • Organic Acids • Formic (Mite-Away II) • Oxalic • Trickling Method • Fogging • Sugars • Sucrocide • Powdered Sugar (“Dowda” Method)
Apilife Var • Essential oil-based treatment: thymol, eucalyptus, camphor, menthol in vermiculite ‘tablets’ or wafers. • Each package contains two wafers. Break a wafer into 4 pieces and put on top bars of brood nest. • Repeat treatment 3 to 4 times 7-10 days apart. • 60 - 95% efficacy. Average 75%. • Temperature dependent. Range should be 64º - 86º. Do not use above 90º. • No resistance reported. • Honey supers should be off during treatment and not put back on for 30 days following treatment. • Use disposable latex gloves. Eye hazard. Can burn skin.
Apiguard • 85 - 95% efficacy. • Honey supers must be removed but can be returned immediately following treatment. • Temperature range 60º-105º. • Leave open tray of gel on brood nest for 14 days (2 in a double deep). Repeat treatment once. • Also kills tracheal mites. • Eye damage/skin irritant. Manufacturer recommends wearing nitrile gloves.
Organic Acids • Formic Acid • Original U.S. formulation was a gel, Apicure, but packaging problems led to its being pulled from the market. • Now available as liquid-soaked pad, Mite-Away II. • Oxalic Acid • Trickling Method • Fogging (Not practical for most hobbyist/sideliners.) • Lactic Acid - used in Europe; not available in the U.S.A.
Formic Acid: Mite-Away II • Temperatures should be between 50º-80º. If temperatures exceed 82º in the first 7 days of treatment, pads should be removed. • 89 - 98% efficacy. • 21 day treatment. Honey supers may go on immediately after treatment but should not be harvested for 2 weeks. • Remove outer plastic bag but not inner. Use spacer rim and shims under pad. Apply pad hole-side down. • Inhalation and contact hazard. Stand upwind and use nitrile gloves. (Respirator requirement recently rescinded.)
Mite-Away II • Screened bottom boards should be closed during treatment. • Entrance reducers should be removed.
Oxalic Acid, Trickling Method • Not a stand-alone treatment. • Colony must be broodless (Late October - December.) • Bees should be reduced to 2 deeps, or equivalent. • Use acid-resistant gloves. • Knocks down mite population phoretic on wintering bees.
Oxalic Acid: Trickling Method, cont’d. • Make a 3.2% solution by adding 3 level tablespoons (34 gms) oxalic acid crystals (dip + sweep method of measuring) to 1 liter of 1:1 sugar syrup. (Make syrup by putting 5 pounds of sugar in a 1 gallon container. Fill with hot water & stir.) • Use a syringe to trickle about 5 ml. of acid solution in every space between frames occupied by bees. (Dr. Medhat Nasr’s rule of thumb was 50 ml total for strong colonies, 40 ml for weak, divided between the brood boxes.)
Sugar Treatments • Sucrocide • Safe for bees (open brood?) and beekeeper. • Inexpensive. • Labor intensive • “Dowda” Method • See May 2007 ABJ article by Randy Oliver. • Good, safe way to control Varroa populations during honey flow. Efficacy depends on frequency of application.
Sucrocide (Sucrose Octanoate esters) • Mix 1.5 Tablespoons per gallon • Spray each and every frame of bees, both sides. • Repeat at weekly intervals 3x to cover full 21 day brood cycle. • Very labor-intensive. • No restrictions on honey supers. • Temporary eye irritant.
Powdered Sugar Dusting • Use 1 cup sugar per deep. • Place frame with metal screen stretched over it over frames and shake sugar on screen. • Use bee brush to dust through screen. • Repeat for second deep. • Approx. 1/3 of phoretic mites will drop with each treatment. • Repeat as often as desired - weekly, bi-monthly or monthly. Must be used with screened bottom board. • No honey super restrictions.
Other Methods: Mineral Oil • Food Grade Mineral Oil (light viscosity: 70 FG. Available from STE Oil, Texas. www.steoil.com • Fogging (Pedro Rodriguez method) has been shown not to work. • Trickling on frames - mixed results. Some beekeepers report good control with very frequent use (R. Harvey) ; others have not found any benefit. No good scientific studies available.
Other Methods: Drone Trapping • Deliberately introducing and culling drone comb can be a highly effective method of Varroa control. • Can use commercial drone foundation or introduce an empty frame, which the bees will almost always draw out into drone comb. • Remove the comb when brood is capped and dispose of brood + mites.
Drone Culling • One drone brood frame per month can delay necessity for other treatments. • Two frames may be able to eliminate other treatments. • Drawbacks: • If you fail to remove in time, you’re breeding mites. Requires an organized beekeeper! • Long-term effects of reducing an already-depleted honey bee gene pool.
Follow-Up Monitoring • All “Dumb Chemical” treatments, mechanical & biological methods need “Smart Beekeepers” to follow-up by re-checking mite levels after treatment. Failure to do so can cost you your bees. • “Smart Beekeepers” use a variety of techniques in combination with one another. Find a system that works for you and use it.