Helping Florida Queen Producers to Select for Mite-resistant Stock by Using Genetic Marker Assisted Selection.

Commodities

Practices

Varroa are currently responsible for greater losses of
colonies than are any other biological threat, requiring
commercial beekeepers to spend a substantial amount of time
treating colonies with chemicals.  Integrated pest
management (IPM) is key to sustainable operations by reducing the
labor associated with treating colonies, miticide costs, and loss
of bees. Addressing these issues will result in increased profits
and sustainability.  A fundamental tenant of IPM is to use
genetically resistant stock to improve productivity.  This
project focuses on the genetic aspect of IPM.

Some Florida queen producers actively select their own stock for
local adaptation, overall hygiene, vigor and mite resistance. We
plan to include these producers in this study.  We will
determine overall Varroa populations in approximately
500 colonies by performing standard alcohol washes on 300 worker
bees, then collecting nurse bees for SNPs analysis, and finally
rating vigor and defensiveness.  The best 30 colonies with
the lowest Varroa populations will be marked and set
aside, then await the results of the SNPs assay; based these
results further testing using MBB and PKB assay will occur. 

This will aid Florida queen bee producers who, as a result of our
scientific genetic data, can make more effective breeding
decisions based on empirical information, rather than visual
perception and instinct.  As part of this process, the
producers will be part of the field analysis and data collection.
Thus they will be able to perform the screening tests themselves
by the end of the study.

We plan to sample at least 500 colonies in operations managed by
three different queen producers in Florida.  After
discussing stock selection methods with queen producers, we will
inspect their colonies and assign them a unique number. First, we
will assay these colonies for Varroa populations using a
standard alcohol wash.  The alcohol wash is generally
accepted scientific method for accurately measuring the level of
infestation by collecting 300 bees, placing them in a jar of
alcohol, shaking them for 60 seconds, decanting off the liquid
and counting the total number of mites that were washed off of
the bees.  Secondly, for genetic SNPs sampling, we will
collect very young nurse bees, place them in tubes of
ethanol.  Then the samples will be sent to Harpur lab at
Purdue. Lastly, based on this raw field data, we can immediately
identify which are the best colonies that will be tested for MBB
and PKB.

MBB is defined by a honey bee biting one or more legs off a
Varroa.An assay has been developed by Dr. Greg Hunt at
Purdue University (Hunt & Andino ABJ 2011) for
accurately measuring the proportion of chewed mites in a colony.
This will yield measurable results, and a potential tool for
breeding selections. The method has two major components,
collection of mites and evaluation of chewed legs. The collection
of mites in the field by beekeepers is simple.
(1) An oiled board is inserted over the
bottom board (floor) of the hive. (2) The
board is allowed to remain in the hive for 24-48 hours.
(3) The mite boards are removed from the
hives, and brought to safe processing area/lab.  The second
component is evaluation. (4) Sift through
the contents and collect the dark mature mites.
(5) Glue/set the mites "legs up" on a glass
microscope slide/petri dish and count the total number of
Varroa (6) View each mite on the
slide under a low power microscope/15×-handlense and count how
many mites have chewed/missing legs.
(7) Calculate the MBB, as a percentage,
example: 12 chewed mites/36 total mites = 33% of mites having
chewed legs. The collection method is simple for beekeepers to
perform in field with minimal training and tools. The evaluation
component, steps 4-7, requires more skill and is labor
intensive/time consuming. Fortunately, this can be done later,
when beekeepers have more time.

Students at the University of Florida will be involved in
counting the chewed mites, and some of the field work. 
Statistical analysis of the results will be performed and
presented in the final report.

Pin-killed Brood assay is performed by using an entomological pin
and piecing capped brood.  A section of brood frame is
marked so 50 cells are pieced, killing the pupae, the worker bees
will remove the dead pupae.  After 5-6 hours the frames are
measured for the percentage removed.  This is safer than the
freeze killed methods which require the handling of dangerous
liquid nitrogen.  These results are a proxy for VSH hygienic
behavior.