Economic
Thresholds
&
IPM
Strategy
Dewey M. Caron
University of Delaware
IPM – Integrated Pest
Management
I=INTEGRATED – ideally use of more than pesticide
chemical control
P=PEST – mites sure but applicable to any of the 3 P’s
M=MANAGEMENT – as you mange the bee population
you manage the P’s
“Several techniques are employed
simultaneously to solve
specific pest problems”
Alternative BMP’s Best Management Practices
names: Alternative Treatments (non-pesticide)
IPM
IPM is a decision-making process for
control of PESTS
PEST = pathogens, parasites, predators of
honey bees, their colonies &/or products
Bee Mites have changed the face of
beekeeping – no longer bee-havers
We are management specialists!
Four Fundamental
Strategies for Pest
Management
Do nothing
Reduce numbers of pest
Reduce susceptibility of the host
Use combinations of the last two
Goals to Focus on
When Developing a
Pest Management Plan
Reduce pest status
Conserve environmental quality
Accept tolerable pest densities
Improve net profits
Timing…NOT calendar treatments
Implementation of Pest
Management Strategies
Pest identification
Pest population assessment
Economic evaluation*
Timing of controls
* Is economic damage possible/imminent?
How to Achieve These
Goals
Efficient sampling methods
Valid decision guidelines
Integrating a number of effective
tactics for an overall plan of
attack
Acceptance of higher mite levels
IPM in Practice
MONITORING
Mite levels fluctuate within &
between seasons. We must carefully
sample (=scout or 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 ID mite & predict #
Varroa mite – a pest or vector?
K-Wing or Wingless bees of value?
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
SOLUTION?
Control Collapse w/ Pesticides
“Resistant”
mites increase
with each
generation
Due to:
(1)selection
pressure
(2)Sub-optimal
exposure
Economic Threshold
80
Avoid exceeding economic
injury level
70
EIL
60
Apply controls
50
ET
40
Average
density
30
20
10
0
Time
Mite Numbers
Increase seasonally
Mite Numbers
High mite yr
Low
mite
yr
Vary between colonies & years
Monitoring
On brood
- worker
- drone
On bees
- ether roll
- powdered sugar
- alcohol wash
In colony
- Sticky board
IPM THRESHOLD
Monitoring can supply a number
- a “guesstimate”
One or more numbers can be obtained
- use number(s) to evaluate mite population
- one mite in sample = X mites in colony
(1=50 in U.S. -- 1=100 Europe)
Determine an appropriate risk level
- one mite vs 100 vs 1000?
Assumption: 3000 mites in fall represents a
minimally acceptable conservative risk???
Balance of costs vs benefits
Valadation of mite sample [bars] to actual numbers [background]
Not perfect but good correlation
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
Threshold
Spring/summer (April or May or Mid-June)



Sticky boards – over 5-10
Adult bees – over 3-4
Brood – over 5%
Exceeding threshold means additional control may be useful
Pre-fall (mid-August, Sept too late!)



Sticky boards – over 50-60 means additional control
Adult bees – over 10-12
Brood – over 5-10%
Exceeding threshold means additional (chemical)
control needed
IPM Mite Control Triangle
Varroa Mites – cultural control
Apiary site location
Comb culling
Small-sized cell base
Requeening w/ Resistant
(tolerant) stock



Hygienic queen stock
SMR (surpressed mite resistance)
Russian stock
From Martin: In Mites
of the Honey Bee
Varroa Mites – physical control
Screened bottom boards (season long)
Drone brood trapping (1X to 8X)
Heat (104-110◦F for 4 hrs)
Varroa Mites – physical control
Screened bottom board
Varroa Mites – biological control
No identified control agent so far
Best choice seems to be a virus or
fungus
Varroa Mites – Chemical control
Miticides - Apistan®; Checkmite+®; Amitraz®
Formic acid - Apicure®; Mite-Away II®
Other acids (acetic; oxalic)
Essential oils


Thymol Api Life VAR® [thymol + others]; ApiGuard®
Others -thyme, citronella, clove, camphor, eucalyptol
Semiochemcials – Nasanov gland pheromones
+ others
Mineral/vegetable oil (FGMO), esters

Grease patties; oil machines, Sucrocide ®
Drying agents

Diatomaceous earth, talc, powdered sugar
Varroa Mites - Chemical Control
Pesticides – natural/synthetic need to be
approved (registered) for legal use
Emergency registration (i.e. Checkmite+)
means emergency – temporary answer
Natural doesn’t mean less toxic
DUMB chemicals (less toxic, not prepackaged) need SMART beekeepers