THE OLD
SOLUTION
“Resistant”
mites
increase
with each
generation
Due to:
(1)selection
pressure
(2)Suboptimal
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
1st 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
Monitoring
On brood
- worker
- drone
On bees
- ether roll
- powdered sugar
- 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
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 prepackaged) 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




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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
QC
Q
QC
Swarming Hive
Artificial swarm
Q
New Brood Box on old site
QC
QC
Swarming Hive – Moved to
one side
Artificial swarm
Queen on drawn comb
with only open brood
in new box
Q
New Brood Box on old site
Fill with foundation
QC
Original Hive – Moved to
one side leave one open
queen cell
Artificial swarm
Queen on drawn comb
Move over supers
with only open brood
in new box
Q
New Brood Box on old site
Fill with foundation
QC
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
Artificial swarm
After 5 weeks
Bait combs now sealed
Laying
Queen
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
Icing sugar
Powdered sugar
Measuring cup
(marked at ½ cup)
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.
Shaking
out the
mites
Mites (dark spots) in sugar
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
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 nonchemical 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