Presentation on theme: "THE OLD SOLUTION “Resistant” mites increase with each generation Due to: (1)selection pressure (2)Sub- optimal exposure."— Presentation transcript:
THE OLD SOLUTION “Resistant” mites increase with each generation Due to: (1)selection pressure (2)Sub- optimal exposure
Varroa mite – a pest or vector? Damage to the colony is the result of virus transmission; we should not wait until we can see mites on bees or damaged bees before we act.
Varroa Control All colonies are infested with varroa Our aim is to keep level of infestation low Monitoring levels of varroa is essential Must use principles of IPM Must not rely on only one control method
IPM in Practice MONITORING Mite levels fluctuate within & between seasons. We must carefully sample ( monitor) and then use best estimates to determine risk level – if risk elevated we control! We MUST -Understand bee/mite life cycle -be able to identify mite & predict infestation level
Illustration series from Martin IN: Mites of Honey Bees Dadant & Sons, Inc 2001 Adult female mite enters larval cell as it completes development. She hides on side wall as pre-pupa spins cocoon
In 60 hours she lays 1 st egg (male). After 24 hours she lays female egg one every 24 hours
Her son (male) develops feeding on pupa & mates w/ sister as she matures
When adult bee emerges 1.3 adult female mites are mature – if eggs on drone 3X are mature
After 4-11 days from emerging, the mite will enter a cell 1-2 days before sealing On average, 1.3 new adult mites will survive from worker cells, but 3-4 will survive from drone cells
Monitoring Mite Levels Essential to know mite levels So as to treat at appropriate time So as to treat at appropriate time Not waste with unnecessary treatments Not waste with unnecessary treatments Know if treatment is working Know if treatment is working Detect reinfestation by drifting/robbing Detect reinfestation by drifting/robbing
Monitoring On brood - worker - worker - drone - drone On bees - ether roll - ether roll - powdered sugar - powdered sugar - alcohol wash - alcohol wash In colony - Sticky board - Open mesh floor
Threshold An acceptable level of pests [mites] – determine necessity of further controls A number to use to evaluate mite control efficacy efforts Allows estimation of risk if no pesticide chemical is integrated into the control The basis for IPM – a decision process utilizing modern pest control practices
IPM THRESHOLD Monitoring can supply a number - a “guesstimate” Determine an appropriate risk level - one mite vs 100 vs 1000? The level at which treatment is needed will depend on the level, and type, of virus infection in the colony USA Assumption: 3000 mites in fall represents a minimally acceptable conservative risk??? Balance of costs vs benefits
Quick Guide to Action Needed Monitor natural mite drop at regular intervals during the active season 24 hour mite drop during active season 0-2 no action needed 0-2 no action needed 3-7 plan for treatment within a month 3-7 plan for treatment within a month 8+ treat immediately 8+ treat immediately
Varroa Mites – cultural control Apiary site location Minimise drifting and robbing Minimise drifting and robbing consider bees natural behaviour in the wildconsider bees natural behaviour in the wild Co-ordination with nearby beekeepers Reduce risk of re-infestation Reduce risk of re-infestation
Varroa Mites – cultural control Apiary site location Minimise drifting and robbing Minimise drifting and robbing Co-ordination with nearby beekeepers Reduce risk of re-infestation Reduce risk of re-infestation Requeening with Resistant (tolerant) stock Hygienic queen stock Hygienic queen stock SMR(suppressed mite reproduction) SMR(suppressed mite reproduction) Russian stock Russian stock
Varroa Mites – cultural control Apiary site location Minimise drifting and robbing Minimise drifting and robbing Co-ordination with nearby beekeepers Reduce risk of re-infestation Reduce risk of re-infestation Requeening with Resistant (tolerant) stock Hygienic queen stock Hygienic queen stock SMR(suppressed mite reproduction) SMR(suppressed mite reproduction) Russian stock Russian stock Experimental methods Small-sized cell base Small-sized cell base Wide frame spacing Wide frame spacing Top-bar hives Top-bar hives
Varroa Mites – physical control Screened bottom boards (all year round) Drone brood trapping Icing sugar dusting Swarm manipulation
Screened bottom board Left on all year will reduce mite levels
Drone Brood Trapping Will halt the build up if drone brood is removed regularly Very effective if bait comb used in broodless colony
Icing sugar dusting Use proper icing sugar Use proper icing sugar Non-toxic, can be used in active season Non-toxic, can be used in active season Low efficiency, but repeated weekly can be beneficial Low efficiency, but repeated weekly can be beneficial Remember – it does not kill the mites, so they need to be trapped on a screened floor (bee-proof)
Varroa Mites – biological control No identified control agent so far Best choice seems to be a virus or fungus
Varroa Mites - Chemical Control Pesticides – natural/synthetic need to be approved (registered) for legal use Natural doesn’t mean less toxic DUMB chemicals (less toxic, not pre- packaged) need SMART beekeepers
Chemical Control - Organic Essential Oils Thymol (apiguard) – use in autumn Other essential oils – insufficient evidence
Chemical Control - Organic Essential Oils Thymol (apiguard) – use in autumn Other essential oils – insufficient evidence Organic Acids !caution-caustic Oxalic acid – use when brood free, usually winter Formic acid – with dispensers can be used in autumn (MiteAway II may be available soon) Lactic acid – out of favour as difficult to apply
Chemical Control -Pesticides Apistan or Bayvarol Synthetic pyrethroids Synthetic pyrethroids Significant resistance in most areas Significant resistance in most areas May harm drone sperm if used in spring May harm drone sperm if used in spring May be harmful if bees forage crops treated with other pesticides May be harmful if bees forage crops treated with other pesticides Should only be used if a resistance test has been carried out first Should only be used if a resistance test has been carried out first Amitraz & Coumaphos – not approved
Three Seasons of Varroa Control Winter Oxalic acid Oxalic acidSpring-summer Bait combs, drone trapping, sugar, splits Bait combs, drone trapping, sugar, splits Oxalic acid if broodless and not storing Oxalic acid if broodless and not storingAutumn Thymol, formic acid, sugar Thymol, formic acid, sugar
Swarms When preparing to swarm, egg laying is reduced, so more varroa are outside the cells The new swarm has no brood, so is suitable for varroa control: Sugaring Sugaring Oxalic acid Oxalic acid Bait comb Bait comb
Powdered Sugar Sampling to monitor Varroa mite populations in Honey Bee colonies Powdered Sugar Sampling to monitor Varroa mite populations in Honey Bee colonies
3 Basic ways to Monitor Mites 1. On Brood Impale capped drone pupae with capping scratcher and count number of cells infested = % brood infested = % brood infested Count # brood infested not total mite count
3 Basic ways to Monitor Mites 2. Natural mite drop Sticky Board Mites dropped over three days captured on sticky/vaseline-coated board = average mite drop/day 2 mites
3 Basic ways to Monitor Mites 3. Mites on adult bees Sugar roll Shake mites off nurse bees using icing sugar Shake mites off nurse bees using icing sugar = mites/sample (~300 bees)
Sugar shake method Collecting a sample of adult bees (1/2 cup or approximately 300) from the brood area and then vigorously shaking the sample with icing sugar (for 1 minute) causes the majority of mites (>90%) to dislodge from their hosts. We can then shake out the mites onto a light coloured collecting dish and count the mites.
Sampling Equipment Measuring cup (marked at ½ cup) Wide mouth quart Mason jar w/ modified lid (8 mesh screen) White [mite] counting dish Powdered sugar tablespoon Colony to sample for icing sugar sampling Icing sugar tablespoon
Obtaining Bee Sample Step 1: Open colony to brood cluster – Select 1 or more frames w/ open brood & nurse bees - look to be certain queen is not on frame Frame of open brood with some capped drone cells
Obtaining Bee Sample 2 Step 2: Shake bees from 1-3 brood frames into 5 gallon bucket or plastic wash basin – we prefer if bees are collected from 3 different frames but risk of queen injury is greater
Obtaining Bee Sample 3 Step 3: Scoop up a ½ cup sample of bees (~300 adults) from bucket – if you shake bucket, bees will clump together for ease of obtaining bee sample ½ cup scoop from cardboard box
Obtaining Bee Sample 4 Modified lid (screen mesh replaces solid top) Step 4: Transfer ½ cup bees to wide mouth mason jar and screw on lid with modified 8 mesh screening
Add powdered sugar Step 5: Add 1-2 heaping tablespoons icing sugar to bees in the sample jar through modified screened lid Push powdered sugar through lid mesh
Powder sugaring the bee sample Step 6: Shake the sample vigorously for 1-2 minutes to distribute the powdered sugar over the bees – if bees not covered add more sugar. Keep jar vertical when shaking.
Shaking out the mites Step 7: Invert jar over a white dish and vigorously shake mites and sugar from jar – shake until no mites or powder sugar comes out Mites (dark spots) in sugar
Optional reshake with additional sugar Shake out sugar with mites until no more drop -- count total number of mites Shake out sugar with mites until no more drop -- count total number of mites Return bees to their hive Return bees to their hive NOTE: Shaking in icing sugar does not harm the bees. NOTE: Shaking in icing sugar does not harm the bees. They will clean off the sugar and return to normal duties after release. Add another ½ tablespoon of icing sugar and reshake for one minute.
Calculate Number of mites/bee Step 8: You can estimate ~300 in 1/2 cup and release sugar coated back into their hive. OR To get a more accurate count (and see if more mites are present) kill the bees w/ alcohol or soap to wash then Strain sample to count number of bees -- divide number of mites by # bees = # mites/bees NOTE: Shaking in powdered sugar does not harm the bees. They will clean off the powdered sugar and return to normal duties after release. NOTE: Shaking in powdered sugar does not harm the bees. They will clean off the powdered sugar and return to normal duties after release.
The sugar shake number of shaken mites is a “guesstimate” of the level of mites in the bee colony. It can be used to make a decision on further treatment needs &/or to assess past treatment effectiveness. It will enable you to monitor the development of mites over the season and from one season to the next.
Deciding on what action needs to be taken Step 9: When was sample taken? Before supering – April/May Before supering – April/May Treat when levels are 2-3 mites/sample Mid flow (optional) –June/July Mid flow (optional) –June/July Remove crop and treat when 10 or more mites/sample Post honey flow before final autumn brood rearing – Aug/Sept Post honey flow before final autumn brood rearing – Aug/Sept Treat when levels are 10-12 mites/sample These thresholds assume normal size colonies with brood
Application of Results Summary It is recommended that a minimum of 2 samples be taken each year. Spring sampling (April to mid- June) will help establish the colony condition before/during the active season. If 2-3 or mites are in sample colony/apiary you should perform a non- chemical IPM treatment to reduce mite buildup. At a minimum, an autumn [no later than mid-August] assessment should be made of each colony/apiary. If more than 10-12 mites are shaken. further (usually chemical) treatment is needed to help ensure over winter survival. If more than 10-12 mites are shaken. further (usually chemical) treatment is needed to help ensure over winter survival.
For Additional Information See website http://MAAREC.cas.psu.edu Courtesy Univ of GA