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

Adult female mite enters larval cell as it completes development.

She hides on side wall as pre-pupa spins cocoon Illustration series from Martin IN: Mites of Honey Bees Dadant & Sons, Inc 2001

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  Not waste with unnecessary treatments  Know if treatment is working  Detect reinfestation by drifting/robbing

On brood - worker - drone On bees - ether roll - powdered sugar - alcohol wash In colony Sticky board Open mesh floor

Monitoring

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 M onitoring can supply a number a “guesstimate” D etermine 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???

B alance of costs vs benefits

Threshold

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  3-7 plan for treatment within a month  8+ treat immediately

IPM Mite Control Triangle

Varroa Mites – cultural control

Apiary site location  Minimise drifting and robbing • consider bees natural behaviour in the wild Co-ordination with nearby beekeepers  Reduce risk of re-infestation

Varroa Mites – cultural control

Apiary site location  Minimise drifting and robbing Co-ordination with nearby beekeepers  Reduce risk of re-infestation Requeening with Resistant (tolerant) stock  Hygienic queen stock   SMR(suppressed mite reproduction) Russian stock

Varroa Mites – cultural control

Apiary site location  Minimise drifting and robbing Co-ordination with nearby beekeepers  Reduce risk of re-infestation Requeening with Resistant (tolerant) stock    Hygienic queen stock SMR(suppressed mite reproduction) Russian stock Experimental methods    Small-sized cell base Wide frame spacing 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 Non-toxic, can be used in active season 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    Significant resistance in most areas May harm drone sperm if used in spring May be harmful if bees forage crops treated with other pesticides  Should only be used if a resistance test has been carried out first Amitraz & Coumaphos – not approved

When should you control varroa?

Three Seasons of Varroa Control Winter  Oxalic acid Spring-summer  Bait combs, drone trapping, sugar, splits  Oxalic acid if broodless and not storing Autumn  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  Oxalic acid  Bait comb

Artificial swarm

Q QC QC

Swarming Hive

Artificial swarm

New Brood Box on old site

Q QC QC

Swarming Hive – Moved to one side

Artificial swarm

Queen on drawn comb with only

open

brood in new box

QC Q

New Brood Box on old site Fill with foundation Original Hive – Moved to one side leave one

open

queen cell

Artificial swarm

Queen on drawn comb with only

open

brood in new box

Move over supers QC Q

New Brood Box on old site Fill with foundation Original Hive – Moved to one side leave one

open

queen cell

Artificial swarm

After 1 week QC Q

old site

Swap to other side

Artificial swarm

After 2 weeks Virgin Queen Q

Remove and destroy frame of sealed brood with most of the varroa

Artificial swarm

After 3 weeks

virgin not yet laying, All worker brood emerged, Destroy any remaining drone brood

Virgin Queen Q

Transfer 2 frames of open brood To act as bait combs for varroa

Bait combs now sealed

Laying Queen

Artificial swarm

After 5 weeks Q

Remove and destroy bait combs with most of the varroa

Don’t wait until you see this!

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 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 = 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) Powdered sugar Icing sugar tablespoon tablespoon White [mite] counting dish Wide mouth quart Mason jar w/ modified lid (8 mesh screen) Colony to sample

for icing sugar sampling

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

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

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

Push powdered sugar through lid mesh Step 5 : Add 1-2 heaping tablespoons icing sugar to bees in the sample jar through modified screened lid

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.

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

Shaking out the mites

Mites (dark spots) in sugar

Optional reshake with additional sugar Add another ½ tablespoon of icing sugar and reshake for one minute.

Shake out sugar with mites until no more drop -- count total number of mites Return bees to their hive NOTE: Shaking in icing sugar does not harm the bees. They will clean off the sugar and return to normal duties after release.

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.

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   Treat when levels are 2-3 mites/sample 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 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.

For Additional Information

See website http://MAAREC.cas.psu.edu

Courtesy Univ of GA