current and future management strategies for varroa … · current and future management strategies...
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Overview of Honey Bee
Research Projects at OSU
Honey Bee Nutrition
Nosema ceranae
Effects of Pesticides
Applied studies on Varroa control
Resting Worker Bees
How many of you lost significant number of
colonies past winter?
What factor or factors do you think was/were
responsible for your colonies' demise?
How many of you monitor Varroa levels in
your colonies?
How many of you use Varroa mite treatments?
How many of you think Varroa mite is a
problem or responsible for your colony loss?
Varroa mite life cycle
(DM Caron)
First egg after 70
hours and
subsequent eggs
at 30 hour
intervals
Female
Male
PMS (parasitic mite syndrome)
Virus transmission: DWV,
IAPV, KBV, CBPV, BQCV
Before arrival of Varroa, viruses
were considered a minor problem.
Varroa is responsible for direct
injection of virus particles.
PMS
Varroa History of Varroa mite
Why Varroa is a greater menace of European
honey bee but not for the Asian honey bee?
Host-parasite relationship
Natural selection is a long process to get the
resistance or tolerance
In Apis cerana, Varroa is unable to reproduce
in worker brood
Bee Informed Partnership
Survey 2012-13
Beekeepers who reported using
treatment for Varroa lost 26% fewer
colonies than those that did not use a
mite treatment.
Reasons for Colony Losses
2010 Queen failure (30%)
Mites (24%)
Starvation (17%)
CCD (13%)
2011 Queen failure (29%)
Starvation (21%)
Mites (16%)
CCD (12%)
Time
First week of July Last week of July
Pe
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Madras, OR Sampling Results: Varroa mite levels
Varroa IPM In Honey Bee Colonies
IPM
Periodic monitoring of mite levels
Combination of various
available control methods
both chemical and non-
chemical.
Varroa mite economic threshold levels
ET is not universal
ET depends on: geographic location, level of
colony resistance to Varroa etc.
ET range of 20-80 mites/day (sticky board data) is
suggested in the existing literature
ET in terms of percentages (Alcohol wash):
Spring / summer: > 1%
Fall: > 3% Late fall / winter: > 10%
Honey bee and Varroa mite population dynamics
Scientificbeekeeping.com
Of course don’t get the mite loads to this level !!
Varroa mite treatments should not be
calendar based but based on realistic
mite population levels.
Early brood rearing means early mite
control strategies to be implemented.
Treatments
Synthetics
(Organophosphates, Synthetic pyrethroids)
Organic chemicals
Amitraz (Apivar) Contact miticide
2 strips per brood chamber
Degrades relatively faster (3-4
weeks)
Some important considerations when
using Apivar Results can be variable depending on factors
such as: Dose and placement of strips.
Appears to decrease mite populations gradually.
Using in spring may be the best option.
Risk of resistance development....resistance
development can be delayed following removal
directions and rotating with other available
options.
Apiguard
Thymol
(slow release gel)
Temperature dependent
(60-100º F)
Also active against tracheal
mites
Treatment % age decrease in brood
(uncapped + capped)
Mite mortality
50 gm on top with spacer 18 77
50 gm in middle with spacer 26 86
50 gm on top without spacer 26 73
50 gm in middle without
spacer
39 80
25 gm on top with spacer 26 75
25 gm in middle with spacer 22 84
25 gm on top without spacer 26 71
25 gm in middle without
spacer
37 82
No Queen loss observed in any of the experimental hives
Mite-Away Quick
Strips (MAQS)
HopGuard
MAQS and Hopguard
Mite-Away Quick Strips (MAQS)
Formic acid (46.7%)
Recommended dose: 2 strips per treatment
Treatment period: 7 days
Temperature range: 50-92ºF
Colony size: colony cluster covering a minimum of 6
brood frames
Excessive temperatures (>95ºF can cause excessive
brood mortality and absconding)
Kills male and female mites in capped cells
(advantage: mite reproduction is restricted)
(is there a problem in pupal development?)
Treatments
MAQS Apiguard Hopguard Control
Infe
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eve
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tme
nt
(perc
en
tag
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f m
ites)
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Efficacy of MAQS, Apiguard and Hopguard
Oxalic Acid
3% Oxalic acid sprayed
3-4 ml per comb side
killed 98% mites.
Ideal when colonies are
broodless (Nov or Dec).
Not registered for use in
The U.S.A.
Cultural Methods
(Non chemical treatments)
Drone comb traps
Screened bottom board
Powdered sugar dusting
Other strategies to reduce mite
reproduction
Small cell foundation
-may be we will increase additional cycle of
brood providing mites more opportunity to
breed
-also may be putting selective pressure on
mites to develop faster (reduce life cycle)
Creating intermittent brood less periods
Biological Control
Predatory Mite: Stratiolaelaps scimitus
Stratiolaelaps scimitus is a soil dwelling
predatory mite
Currently used for controlling Fungus gnats and thrips.
10 Treatment Colonies
10 Control Colonies
Control Colony Predatory Mite Treatment Colony
Mite with no damage
Mites with damaged
appendages
Future Strategies for Varroa Control
RNAi (interference)
Gene knockdown or gene silencing and stop
protein expression (done by synthesizing a double-
stranded RNA).
DNA…….mRNA…….rRNA (directs the translation of
mRNA in to proteins).
dsRNA impairs translation of viral proteins-reduces
viral replication.
May be a therapeutic alternative in the future.
Questions???