Inbreeding effects of queen and workers on colony traits in the honey bee

Full text

Original
article
Inbreeding
effects
of
queen
and
workers
on
colony
traits
in
the
honey
bee
K.
Bienefeld,
F.
Reinhardt
F.
Pirchner
Lehrstuhl
für
Tierzucht
der
Technischen
Universität
München,
8050
Freising-Weihenstephan,
FRG
(received
24
October
1988,
accepted
3
July
1989)
Summary —
Inbreeding
coefficients
of
queens
and
workers
of
5581
controlled
mated
colonies
were
estimated.
During
a
period
of
over
30
years
inbreeding
increased
by
0.15%
in
queens
and
0.06%
in
workers
per
year.
The
highest
inbreeding
coefficients
were
44%
in
individual
queens
and
45%
in
in-
dividual
worker
groups,
respectively.
Using
partial
regression,
the
importance
and
consequences
of
inbreeding
on
colony
traits
were
ascertained.
Inbreeding
seems
to
affect
the
two
castes
differently.
Colony
performance
with
regard
to
honey
and
wax
is
significantly
depressed
(-6%
and
-8%,
res-
pectively,
per
1 %
inbreeding)
by
the
inbreeding
of
the
workers.
In
our
material,
inbreeding
of
queens
did
not
affect
colony
efficiency
except
when
workers
were
also
inbred.
Workers
can
compensate
for
inbreeding
depression
of
queens,
but
the
reverse
is
not
true.
Inbreeding
of
workers
leads
to
calmer
and
less
aggressive
colony
behaviour,
whereas
inbreeding
of
queens
has
the
opposite
effect.
Swarming
tendency
increased
with
increased
inbreeding
of
workers.
In
contrast,
queens
with
moder-
ate
inbreeding
have
colonies
with
the
highest
swarming
tendency.
Honey
production,
calmness
dur-
ing
examination
and
swarming
tendency
show
significant
interactions
between
the
inbreeding
level
of
queens
and
workers.
Apis
mellifera—
inbreeding
-
honey
production
-
aggressiveness
-
swarming
tendency
INTRODUCTION
Inbreeding
is
a
powerful
tool
for
creating
genetic
diversity
but
it
depresses
performance,
particularly
in
components
of
reproductive
fitness
including
fertility,
viability
and
production
traits
(Dickerson,
1973).
In
the
honeybee
inbreeding
de-
pression
was
found
both
in
workers
(Bruckner,
1975,
1980;
Khischa,
1976;
Kepena,
1976)
and
in
queens
(Hoopin-
garner
and
Farrar,
1959;
Khischa,
1976;
Moritz,
1982)
for
various
traits.
This
ex-
plains
the
poorer
efficiency
(Plass,
1953;
Cale
and
Gowen,
1956;
Khischa,
1976)
and
altered
colony
behaviour
(Plass,
1953).
However,
these
experiments
give
no
information
about
the
relative
importance
of
inbreeding
in
queen
and
workers
to
colony
traits,
which
are
assumed
to
be
af-
fected
by
both
castes
simultaneously
(Chevalet
and
Cornuet,
1982).
In
the
present
study
a
method
is
described
for
computing
the
inbreeding
coefficients
(F)
in
large
sets
of
colonies
with
respect
to
characteristics
in
reproduction,
under
controlled
mating
conditions.
Computing
Ffor
queens
and
workers
of
each
colony

and
relating
them
to
recorded
colony
traits
permits
the
separation
of
inbreeding
ef-
fects
of
the
two
castes.
MATERIALS
AND
METHODS
The
study
is
based
on
data
collected
from
ap-
proved
beekeepers
organized
in
two
bee
breed-
ing
societies
in
Lower
Saxony
(F.R.G.)
and
a
bee
breeding
society
in
Hamburg
(F.R.G.).
In
addition
to
the
results
from
&dquo;stud-books&dquo;
from
beekeepers
(n=96),
the
Research
Institutes
for
Bee
Breeding
in
Celle
(Lower
Saxony,
F.R.G.),
Kirchhain
(Hessia,
F.R.G.)
and
Lunz
(Austria)
provided
data
from
their
testing
stations.
The
performance
tests
by
beekeepers
and
the
Bee
Research
Institutes
were
carried
out
in
the
same
manner
without
essential
modifications
during
the
period
analysed.
The
honey
yield
was
taken
as
weight
difference
of
combs
before
and
after
extracting
honey
plus
an
estimate
of
honey
left
in
the
broodnest.
Wax
production
was
estimated
by
the
number
of
honey
and/or
drone
combs
times
a
factor
between
0.06
and
0.07
(depending
on
comb
size).
Aggressiveness
(de-
fensive
behaviour -
from
very
gentle
to
vicious),
calmness
during
examination
(running
of
the
bees
during
examination),
spring
development
(time
when
the
super
had
to
be
given
to
the
col-
ony)
and
swarming
tendency
(occurrence
of
swarming
symptoms
and
reaction
of
the
colony
to
means
of
preventing
swarming)
were
scored
subjectively.
The
scoring
system
ranged
from
4
(very
good)
to
1
(very
bad).
Intermediate
marks
(for
example,
2.5)
were
possible
(Table
I).
For
details
of
the
performance
test
the
read-
er
is
referred
to
the
paper
by
Ruttner
(1972).
The
organisation
of
the
breeding
scheme
has
been
described
by
Tiesler
(1988).
Only
colonies
(n
=
5581)
from
controlled
matings
or
artificial
in-
semination
were
used
in
the
analyses.
The
mat-
ing
stations
are
located
on
islands
along
the
North
German
coast.
All
are
sufficiently
far
away
from
the
mainland
and
from
each
other
to
main-
tain
complete
isolation
from
unwanted
drones.
At
these
&dquo;island
mating
stations&dquo;
an
average
of
6
(varying
from
4
to
10)
colonies
with
sister
queens
(queens
descended
from
one
dam,
who
were
also
mated
at
an
island
mating
station)
provided
the
breeding
drones.
Genetic
relationship
within
and
between
colonies
without
Inbreeding
The
genetic
relationship
(a)
between
two
individ-
uals
can
be
calculated
as
follows
(Maldoot,
1948).
where
<D
=
probability
of
identity
of
matemal
genes
in
2
animals;
!’
=
probability
of
identity
of
paternal
genes
in
2
animals.
Two
randomly
chosen
females
(queens
or
workers;
because
of
the
large
number
of
work-
ers
per
colony
the
genetic
relationship
between
2
worker
offspring
groups
of
different
colonies
is

equivalent
to
the
genetic
relationship
between
2
randomly
chosen
individual
workers
from
these
2
colonies)
from
1
colony
have
the
same
dam
(<1>
=
0.5)
but
because
of
the
multiple
mating
of
their
dam,
possibly
different
paternal
descent.
Therefore
at
the
island
mating
stations
three
val-
ues
for
<1>’
are
possible.
The
probability
(P
i)
of
the
three
possibilities
depends
on
the
number
of
drones
per
queen
(D )
and
the
number
of
drone-
producing
queens
(S)
at
the
island
mating
sta-
tions.
Possibility
1:
Descent
from
the
same
drone
(= same
gamete)
Possibility
2:
Descent
from
different
drones
of
the
same
drones-producing
queen
(=
different
gametes
of
the
same
sire,
Polhemus
et
al.,
1950)
Possibility
3:
Descent
from
different
drones,
which
come
from
different
but
related
(a[s])
drone-producing
queens
The
average
probability
of
identity
of
pater-
nal
genes
((D’)
gives
The
genetic
relationship
between
the
drone-
producing
queens
is
on
average
the
same
as
the
relationship
to
be
estimated.
<1>’ can
be
expressed
as
follows
I I
I
Which
reduces,
after
some
rearrangements,
to
In
order
to
compute
the
average
genetic
rela-
tionship
between
two
females
from
different
col-
onies
but
identical
paternal
descent
(a
*
),
possi-
bility
1
(same
drone)
has
to
be
excluded,
because
drones
only
mate
once.
Therefore
11>’
results
as
follows
Like
(7)
eq.
(9)
included
only
the
variables
D
and
S
so
(9)
can
also
be
expressed
as
a
func-
tion
of
these
variables.
Substitution
of
D
=
8
(Laidlaw,
1974;
Woyke,
1985)
and
S
=
6
(notes
from
the
bee
breeding
societies
in
Lower
Saxony)
in
eqs.
(9)
and
(10)
gives
Computation
of
the
coefficients
of
in-
breeding (t7
Heijden
et
al.
(1977)
and
Dempfle
(1987)
de-
rived
efficient
methods
to
compute
the
numera-
tor
relationship
matrix
(NRM)
for
large
sets
of
animals
For
our
purposes
only
the
diagonal
elements
1
+
Fi
(Henderson,
1976)
of
the
NRM
have
to
be
cal-
culated.
Fi
is
the
coefficient
of
inbreeding
of
ani-
mal
i
(queen
or
an
&dquo;average
worker&dquo;).
The
com-
puting
technique
has
been
fully
described
by
Bienefeld
(1968a).
M
is
a
triangular
matrix
con-
taining
only
unity
in
the
diagonal
and,
in
the
case
of
animal
i
(row i),
in
the
off
diagonals.
Animal j
and
k
are
the
par-
ents
of
L
The
elements
of
the
diagonal
matrix
D
are
the
theoretical
variances
of
the deviation
of
the
breeding
values
of
the
individuals
from
the
true
full
sib
means.
These
depend
on
the
infor-
mation
available:

where
Fs
and
FD
are
the
coefficients
of
inbreed-
ing
of
the
parents,
which
have
to
be
calculated
(and stored) first.
This
method
does
not
fit
the
characteristics
of
reproduction
of
the
honey
bee,
because
the
paternal
descent
cannot
be
ascribed
to
a
single
diploid
sire,
but
only
to
a
mixture
of
gametes
from
related
sires
(sister
queens).
That
means
that
the
theoretical
covariance
(a)
between
re-
lated
individuals
is
changed
compared
to
nor-
mal
diploids.
Considering
eqs. (11)
and
(12),
the
following
values
can
be
derived.
Considering
these
deviations
in
the
corre-
sponding
off-diagonal
elements
in
D
correct
computation
of
the
coefficient
of
inbreeding
in
the
honey
bee
is
possible.
However,
the
accura-
cy
of
the
computation
of
the
genetic
relationship
and
the
coefficient
of
inbreeding
depends
on
the
agreement
between
assumptions
(D=8
and
S=6
respectively)
and
reality.
But
variation
of
these
variables
in
a
realistic
range
(S
from
4
to
9
and
D from
5
to
11)
does
not
result
in
any
serious
deviation
from
the
standard
situation
(Bienefeld,
1988a).
The
method
is
also
suitable
for
large
sets
of
colonies,
but the
dimension
of
the
matrices
is
twice
the
number
of
colonies
because
the
in-
breeding
coefficient
of
the
queen
and
the
&dquo;aver-
age
worker&dquo;
of
each
colony
has
to
be
computed.
Inbreeding
effects
The
statistical
model
used
to
quantify
the
in-
breeding
effects
of
queen
and
workers
was
Model
I
xjk = u + % + B j + b2 FQ + bN F* + qjk
where
Yj
k
=
colony
trait
of
the
k
th
colony
with
coefficient
of
inbreeding
(FO)
of
the
queen
and
coefficient
of
inbreeding
(Fw)
of
workers,
meas-
ured
in
the
i
th
year
by
the
j
th
beekeeper;
u
=
population
mean;
Yi
=
effect
of
the
i
th
year
(i
=
1-35);
Bj
=
effect
of
the /&dquo;
beekeeper
(j
=
1-96);
W
=
coefficient
of
inbreeding
of
the
queen
(0%-
44%)
of
the
k
th
colony;
Fw
=
coefficient
of
in-
breeding
of
the
workers
(0%-45%)
of
the
k
th
colony;
b2
=
partial
coefficient
of
regression
of
the
colony
trait
on
the
level
of
inbreeding
of
the
queen;
bN
=
partial
coefficient
of
regression
of
the
colony
trait
on
the
level
of
inbreeding
of
the
workers;
e,jk
=
random
residual
error.
By
applyng
the
following
model,
interactions
between
the
inbreeding
level
of
queen
and
workers
within
colonies
can
be
isolated
Model
11
ejmlk
where
Y
jmlk
=
colony
trait
of
the
k
th
colony
with
a
combination
of
inbreeding
level
m
of
the

queen
and
level
I of
workers,
measured
in
the
ith
year
by the I
h
beekeeper;
F,
Bj
=
as
in
model
I;
FLQ
m
=
effect
of
the
M
th
inbreeding
level
of
the
queen
(m
= 1-5);
FLWi
=
effect
of
the
lth
inbreed-
ing
level
of
the
workers
(!=1-5):
FL
qw
ml
=
effect
of
the
interaction
between
the
level
of
inbreed-
ing
of
the
queen
(m)
and
worker
(I
9;jmlk
=
ran-
dom
residual
error.
The
inbreeding
levels
were
divided
as
fol-
lows :
Some
beekeepers
run
the
performance
test-
ing
at
different
locations
within
a
year.
The
indi-
vidual locations
within
a
year
and
a
beekeeper
were
neglected
because
colonies
sharing
the
same
location
also
had
similar
levels
of
inbreed-
ing.
By
including
the
specific
location
in
the
mod-
el
part
of
the
inbreeding,
effects
are
confounded
with
location
effects,
causing
an
underestimate
of
the
inbreeding
effects.
The
results
with
and
without
considering
the
location
are
quite
simi-
lar,
differing
only
in
the
level
of
significance
(Bi-
enefeld, 1988a).
The
subjectively
judged
behaviour
and
devel-
opment
traits
were
not
normally
distributed.
For
that
reason
calculation
for
these
variables
was
done
with
e!va&dquo;abiej
transformed
values.
RESULTS
Figure
1
presents
the
development
of
aver-
age
inbreeding
in
both
castes.
The
yearly
increase
of
an
average
of
0.15%
in
queens
and
of
0.06%
in
workers
is
not
linear,
but
is
characterized
by
ups
and
downs
of
the
lev-
el
of
inbreeding.
The
level,
never
exceed-
ing
5%,
is
relatively
low.
The
highest
indi-
vidual
inbreeding
coefficient
was
44%
in
queens
and
45%
in
workers.
All
colony
traits
recorded
in
Table
II
are
significantly
influenced
by
the
year
and
by
the
beekeeper.
Honey
and
wax
production
of
a
colony
is
significantly
reduced
by
in-
breeding
of
the
worker
(140
g
honey/
percent
inbreeding,
7
g
wax/percent
in-
breeding),
whereas
the
inbreeding
of
the
queen
does
not
influence
these
colony
traits
(Table
II).
Inbred
workers
are
significantly
less
agressive
and
show
more
calmness
during
examination.
Inbreeding
of
the
queen
has
a
significant
effect
on
calmness
during
ex-
amination,
but
in
the
opposite
direction.
Spring
development
is
not
significantly
in-
fluenced
by
inbreeding
of
the
two
castes.
Swarming
tendency
increases
(a
nega-
tive
sign
indicates
a
poorer
classification,
i.e.
greater
swarming
tendency)
significant-
ly
in
workers
as
a
result
of
inbreeding
(Ta-
ble
11).
Honey
production,
calmness
during
ex-
amination
and
swarming
tendency
show
significant
interactions
between
the
in-
breeding
levels
of
queen
and
workers
(Ta-
ble
III).
By
considering
this
interaction
in
the
model,
the
inbreeding
effect
of
queens

on
honey
production
and
swarming
ten-
dency
also
becomes
significant.
As
shown
in
Fig.
2
for
honey
production,
the
impact
of
inbreeding
of
queens
is
most
conspicu-
ous
when
the
workers
of
a
colony
are
also
highly
inbred.
The
LSQ-means
(Figs.
3
and
4)
of
the
other
colony
traits
show
no
clear
tendency.
For
calmness
during
ex-
amination,
the
means
indicate
(as
in
Table
II)
opposite
inbreeding
effects
of
queen
and
workers.
For
swarming
tendency,
a
medium
in-
breeding
level
of
the
queen
is
poorest,
whereas
the
swarming
tendency
in
work-
ers
increases
more
or
less
with
increasing
inbreeding
level.

DISCUSSION
Both
the
development
of
inbreeding,
as
given
in
Fig.
1,
and
the
relatively
low
level
of
inbreeding
are
typical
for
an
&dquo;open
pop-
ulation&dquo;.
In
addition
to
imports
of
foreign
queens,
the
beekeepers
tried
to
limit
in-
breeding
depression
by
&dquo;intra-family
selec-
tion&dquo;
and
by
occasionally
sending
virgin
queens
to
island
mating
stations
with
non-
related
(with
respect
to
the
young
queens)
drone-producing
queens
(Bienefeld,
1988b).
The
justifications
for
these
breeding
strategies
are
shown
in
Table
II
and
Fig.
2.
Inbred
colonies
produce
less
honey
and
wax,
but
it
is
important
to
note
that
this
loss
of
efficiency
is
mainly
caused
by
in-
breeding
of
the
workers.
This
influences
the
colony
performance
in
two
ways.
First
by
less
efficient
(Bruckner,
1975,
1980)
and
morphologically
handicapped
workers
(Khischa,
1976;
Roberts,
1961);
secondly
by
the
mode
of
sex
determination.
The
higher
the
level
of
inbreeding
the
higher
the
probability
of
homozygosity
at
the
sex
locus,
which
causes
brood
losses
(Woyke,
1963).
Similar
to
our
results,
Plass
(1953)
found
that
colonies
in
which
inbred
queens
headed
non-inbred
workers
were
compar-
able
to
normal
colonies
with
respect
to
brood
rearing.
Inbreeding
depression
was
only
observed
in
the
reverse
situation
(in-
bred
workers,
non-inbred
queens).
Surprisingly,
the
inbreeding
of
queens
does
not
affect
honey
performance.
Khis-
cha
(1976)
reported
fewer
and
lighter
ovar-
ioles
in
inbred
queens,
which
may
reduce
their
laying
capacity.
Cale
and
Gowen
(1956)
observed
poorer
honey
production
of
colonies
with
inbred,
but
freely
mated,
queens
(so
workers
were
heterozygotes).
But
contrary
to
our
situation,
Cale
and
Gowen
tested
very
highly
inbred
queens
(F
=
55%-66%)
under
about
5
times
more
favourable
honey
flow
conditions.
Under
this
situation
the
laying
capacity
of

queens
can
be
a
limiting
factor.
Under
un-
stable
honeyflow
conditions
and
a
moder-
ate
inbreeding
level
of
queens,
non-inbred
workers
can
compensate
inbreeding
de-
pression
of
their
dam,
but
queens
cannot
compensate
inbreeding
of
their
workers.
Inbreeding
of
queens
only
leads
to
a
re-
duction
of
performance
if
the
workers
of
their
colony
are
also
inbred
(Fig.
2).
Plass
(1953)
reported
decreasing
ag-
gressiveness
in
inbred
colonies.
We
found
this
tendency
(lower
aggressiveness,
more
calmness
during
examinations)
only
due
to
inbreeding
of
workers.
The
effect
of
in-
breeding
in
queens
was
the
reverse.
Mo-
ritz
(1986)
observed
a
depression
in
physi-
ological
and
metabolic
reactions
in
inbred
workers.
Collins
et aL
(1987)
reported,
by
comparing
European
and
Africanized
geo-
graphical
types
of
honey
bees,
genetic
dif-
ferences
with
respect
to
defensive
behavi-
our.
They
speculated
that
the
different
behaviour
is
caused
by
a
greater
respon-
siveness
to
alarm
pheromones.
If
the
threshold
of
response
to
the
alarm
phero-
mones
is
determined
genetically,
this
threshold
may
be
sensitive
to
inbreeding.
Queen
pheromones
are
known
to
stabi-
lize
behaviour
in
honey
bee
colonies
(Vel-
thuis,
1977;
Crewe,
1982).
Hoffmann
(1961)
found
queenless
colonies
more
restless
and
aggressive.
It
is
likely
that,
in
addition
to
morphological
defects
(Hoopin-
garner
and
Farrar,
1959;
Khischa,
1976),
the
pheromone
output
of
inbred
queens
is
reduced,
causing
a
more
irritable
behavi-
our
of
their
workers.
Plass
(1953)
reported
a
lower
swarming
tendency
but
a
considerably
higher
fre-
quency
of
supersedure
in
his
highly
inbred
colonies.
Contrary
to
this
findings,
we
found
an
increasing
swarming
tendency
due
to
inbreeding
of
workers.
Considering
the
interaction
between
inbreeding
level
of
queen
and
workers
in
the
evaluation
(Ta-
ble
II),
also
a
significiant
queen
effect
was
found.
It
has
to
be
stressed
that
the
individ-
ual
columns
in
Figs.
2,
3
and
4
are
based
on
different
numbers
of
observations,
which
may
give
the
impression
of
dissimi-
larities
between
the
general
tendency
pre-
sented
in
Table
II
and
the
graphical
pres-
entation
of
special
combinations
of
(particularly
in
the
case
of
high)
inbreeding
level
of
queen
and
workers.
This
applies
especially
to
the
trait
&dquo;swarming
tendency&dquo;
(Fig.
4)
computed
from
a
reduced
data
set
only
(Table
I).
However,
Fig.
4
indicates
that
the
rela-
tionship
between
the
level
of
inbreeding
and
swarming
tendency
is
not
linear,
since
the
highest
swarming
tendency
(lowest
LSQ-means)
occurs
at
medium
(6.25%&mdash;
12.5%)
inbreeding
of
queens.
Simpson
(1958)
suggested
that
swarming
as
well
as
supersedure
is
caused
by
a
queen
sub-
stance
deficiency.
Allen
(1965)
found
weather
and
age
of
the
queen
influenced
the
production
of
queen
cells
and
some
ev-
idence
that
older
queens
were
more
likely
to
be
replaced
than
younger
ones.
If
the
assumption
of
a
relationship
be-
tween
inbreeding
of
queens
and
their
pher-
omone
production
is
correct,
the
differenc-
es
between
our
results
and
the
findings
of
Plass
(1953)
are
reconcilable.
Highly
in-
bred
queens
(assumed
to
have
very
low
pheromone
production&mdash;like
old
queens)
may
entail
supersedure,
while
a
medium
level
of
inbreeding
(only
reduced
phero-
mone
production)
may
promote
swarming
of
the
colony.
Supersedure,
discernible
by
extensive
number
of
queen
cells
(Allen,
1965),
is
considered
as
a
sign
of
little
swarming
tendency
(Zander
and
B6ttcher,
1979).
This
may
explain
the
more
favoura-
ble
swarming
tendency
of
colonies
with
highly
inbred
queens
and
the
concomitant
failure
of
the
partial
regression
of
swarm-
ing
tendency
of
the
colony
on
queen’s
in-
breeding
to
reach
significance
(Table
II).

The
increased
swarming
tendency
of
inbred
workers
is
unexpected,
because
of
the
reduced
vitality
(Bruckner,
1975)
and
(due
to
the
mode
of
sex
determination)
smaller
colony
size.
Insufficient
hive
space
has
usually
been
assumed
to
be
a
further
cause
of
swarming
(Simpson
and
Riedel,
1963).
Not
only
did
the
absolute
colony
size
affect
swarming
behaviour,
but
also
worker
concentration
per
unit
(Free,
1968).
Free
(1968)
found
a
dense
worker
concen-
tration
on
the
broodnest
in
small
colonies
and,
possibly
as a
consequence
of
this,
a
tendency
to
swarm.
Résumé &mdash;
Effets
de
la
consanguinité
des
reines
et
des
ouvrières
sur
les
ca-
ractéristiques
de
la
colonie
d’abeilles.
On
a
adapté
au
cas
particulier
de
l’abeille
une
méthode
développée
par
Heijden
et
aL
(1977)
et
Dempfle
(1987)
pour
calculer
les
coefficients
de
consanguinité
dans
de
grandes
populations.
La
consanguinité
des
reines
et
des
ouvrières
de
5581
colo-
nies,
issues
d’accouplement
contrôlé,
a
été
ainsi
calculée.
Sur
plus
de
30
ans
la
consanguinité
des
reines
a
augmenté
de
0,15%
et
celle
des
ouvrières
de
0,06%
par
an
(Fig. 1
Le
coefficient
individuel
de
consanguinité
le
plus
élevé
a
été
de
44%
chez
les
reines
et
de
45%
chez
les
ou-
vrières.
En
appliquant
la
régression
par-
tielle
des
caractéristiques
de
la
colonie
sur
la
consanguinité
de
la
reine
et
des
ou-
vrières
d’une
colonie,
on
a
pu
quantifier
les
conséquences
de
la
consanguinité
sur
ces
caractéristiques
pour
les
deux
castes
sé-
parément.
La
production
miel
et
de
cire
est
at-
teinte
en
premier
lieu
par
la
consanguinité
des
ouvrières,
de
6
et
8%
respectivement
par
1%
de
consanguinité.
Ces
caractéris-
tiques
de
la
colonie
ne
sont
touchées
par
la
consanguinité
de
la
reine
que
si
les
ouv-
rières
sont
elles-mêmes
fortement
consan-
guines.
Les
ouvrières
sont
capables
de
compenser
la
dépression
consanguine
des
reines,
mais
l’inverse
n’est
pas
vrai
(Fig.
1
La
consanguinté
des
ouvrières
rend
la
colonie
plus
calme
et
moins
agres-
sive,
alors
que
la
consanguinité
des
reines
a
l’effet
inverse.
La
consanguinité
des
reines
ou
des
ouvrières
n’exerce
aucune
action
sur
le
développement
de
la
colonie
au
printemps
(Tableau
11).
La
tendance
à
l’essaimage
d’une
colo-
nie
croît
avec
la
consanguinité
des
ou-
vrières.
Elle
est
par
contre
maximale
avec
des
reines
ayant
une
consanguinité
moy-
enne.
La
modification
du
comportement
de
la
colonie
pourrait
être
due
à
une
diminu-
tion
de
la
production
de
phéromones
par
la
reine,
à
une
vitalité
réduite
et
à
une
modification
de
la
sensibilité
des
ouvrières
aux
phéromones.
Des
interactions
signifi-
catives
entre
le
niveau
de
consanguinité
des
reines
et
celui
des
ouvrières
au
sein
d’une
colonie
ont
été
montrées
pour
la
pro-
duction
de
miel,
pour
l’agressivité
durant
l’ouverture
des
ruches
et
pour
la
tendance
à
l’essaimage.
Zusammenfassung &mdash;
Einfluss
der
In-
zucht
von
Königinnen
und
Arbeitsbie-
nen
auf
die
Volkseigenschaften
bei
der
Honigbiene.
Eine
von
Heijden
et
al.
(1977)
und
Dempfle
(1987)
entwickelte
Methode
zur
Berechnung
von
Inzuchtkoef-
fizienten
in
gro&szlig;en
Populationen
wurde
den
reproduktionsbiologischen
Besonder-
heiten
der
Honigbiene
angepa&szlig;t.
Die
In-
zucht
der
Königinnen
und
der
&dquo;Durchsch-
nittsarbeiterinnen&dquo;
von
5
581
kontrolliert
gepaarten
Völkern
konnte
mit
Hilfe
dieser
Methode
berechnet
werden.
Bei
den
Königinnen
errechnete
sich
eine
Inzucht-
steigerung
von
0,15%
und
bei
den
Arbeite-
rinnen
von
0,06%
pro
Jahr
(Abb.
1
Der

höchste
Inzuchtkoeffizient
war
bei
einzel-
nen
Königinnen
44%
und
bei
einzelnen
Ar-
beiterinnengruppen
45%.
Durch
Anwen-
dung
der
partiellen
Regression
der
Volkseigenschaften
auf
die
Inzucht
von
Königin
und
Arbeiterinnen
eines
Volkes
konnten
die
Konsequenzen
der
Inzucht
auf
diese
Volkseigenschaften
für
beide
Kasten
getrennt
quantifiziert
werden.
Der
Honig-
und
Wachsertrag
ist
in
er-
ster
Linie
durch
die
Inzucht
der
Arbeiterin-
nen
um
6%
bzw.
8%
je
Prozent
Inzucht
beeinträchtigt.
Eine
Beeinflussung
dieser
Volkseigenschaften
durch
die
Inzucht
der
Königin
zeigt
sich
erst,
wenn
die
Arbeite-
rinnen
dieses
Volkes
selbst
stark
in-
gezüchtet
sind.
lnzuchtdepression
der
Königin
ist
bei
den
Produktionseigenschaf-
ten
normalerweise
durch
heterozygote
Ar-
beiterinnen
kompensierbar.
Nicht
in-
gezüchtete
Königinnen
sind
dagegen
nicht
in
der
Lage,
Inzuchttolgen
der
Arbeiterin-
nen
auszugleichen
(Abb.
1)
Die
Inzucht
der
Arbeiterinnen
wirkt
sich
auf
die
Aggres-
sivität
und
den
Wabensitz
eines
Volkes
positiv
aus,
während
ingezüchtete
Königinnen
die
gegenteilige
Auswirkung
auf
die
Volksreaktion
haben.
Bezüglich
der
Frühjahrsentwicklung
eines
Volkes konnte
keine
Beeinträchtigung
durch
die
Inzucht
beider
Kasten
nachgewiesen
werden
(Tab.
11).
Die
Schwarmneigung
eines
Volkes
steigt
mit
steigender
Inzucht
der
Arbeiterin-
nen.
Bei
Königinnen
zeigt
sich
bei
mittle-
rem
Inzuchtniveau
die
ausgeprägteste
Schwarmneigung.
Als
Ursachen
des
veränderten
Volksverhaltens
wurde
eine
Beeinträchtigung
der
Pheromonproduktion
der
Königin,
reduzierte
Vitalität
und
veränderte
Pheromonsensibilität
der
Arbei-
terinnen
diskutiert.
Interaktionen
zwischen
dem
Inzuchtniveau
von
Königin
und
Arbei-
terinnen
innerhalb
eines
Volkes
wurden
für
den
Honigertrag,
den
Wabensitz und
für
die
Schwarmneigung
festgestellt.
ACKNOWLEDGMENTS
We
wish
to
thank
F.
Tiesler
(Landesverband
für
Bienenzucht
Hannover
and
Weser-Ems),
Pro-
fessor
Dr.
J.H.
Dustmann
and
Miss
E.
Englert
(Niedersächisches
Landesinstitut
für
Bienen-
zucht
in
Celle,
F.R.G.),
Dr
V.
Maul
(Landesan-
stalt
für
Leistungsprüfungen
in
der
Tierzucht&mdash;
Abteilung
für
Bienenzucht&mdash;Kirchhain,
F.R.G.),
Dr.
H.
Pechhacker
(Höhere
Bundeslehr-
und
Versuschsanstalt
für
Wein-
und
Obstbau
mit
In-
stitut
für
Bienenkunde
in
Linz,
Austria)
and
all
beekeepers
for
providing
the
data.
Financial
support
was
provided
by
the
Deutsche
Fors-
chungsgemeinschaft,
Grant
No.
Pi
90-42.
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