the effect on the foraging behaviour of honeybees of the relative locations of the hive entrance and...
TRANSCRIPT
Applied Animal Ethology, 2 (1976) 141-154 141 o Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
THE EFFECT ON THE FORAGING BEHAVIOUR OF HONEYBEES OF THE RELATIVE LOCATIONS OF THE HIVE ENTRANCE AND BROOD COMBS
J. B. FREE and INGRID H. WILLIAMS
Rothamsted Experimental Station, Harpenden, Hertfordshire (Great Britain)
(Received February 5th, 1976)
ABSTRACT
Free, J.B. and Williams, I.H., 1976. The effect on the foraging behaviour of honeybees of the relative locations of the hive entrance and brood combs. Appl. Anim. Ethel., 2: 141-154.
Hives were provided with upper and lower entrances. When a hive entrance opened di- rectly on to the brood area of a colony, a greater proportion of bees using it collected pollen than when it opened on to an area of the hive with storage comb only, and the proportion of pollen gatherers could be diminished or increased by moving brood combs near to or far from the entrance. Relatively more bees left than entered by an entrance near the brood, particularly when the brood was adjacent to the lower entrance.
On return from foraging, bees tended to remain faithful to one entrance only, but the presence of a queen excluder obstructed the movement of foragers within the hive and, as a consequence, there was a greater tendency for the bees to change entrances in accordance with a change in the position of the brood.
By manipulating the size and shape of the hive entrance it was possible to direct re- turning foragers to the brood combs, and hence to increase their tendency to collect pollen and thus their pollinating efficiency. A series of ten experiments is described.
INTRODUCTION
Honeybees collecting pollen are more efficient pollinators of many crops than those collecting nectar only (Free, 1970, 1971) and especially of crops grown to produce hybrid seed (Free and Williams, 1973 a and b; Williams and Free, 1974), so that increasing the amount of pollen a colony collects also in- creases pollination. Whereas the amount of pollen honeybee colonies collect is probably dependent to some extent on the amount of pollen stores already present (Free and Williams, 1971), a major factor inducing honeybee foragers to collect pollen is the presence of larvae in their colony (Free, 1967; Jaycox, 1970 a and b), and the amount of pollen collected by a colony is positively correlated with the amount of brood it is rearing (Todd and Reed, 1970). Although the odour of the brood, and contact with bees that nurse the brood help stimulate a forager to collect pollen, actual contact with the brood itself is of prime importance (Free, 1967), and foragers prefer to deposit their pollen loads in cells previously used for brood rearing (Free and Williams, 1974).
142
We are now exploring the practical implication of these findings and are at- tempting to find methods of increasing the contact between forager and brood. The present study assesses the effects of the relative locations of the hive entrance and brood combs.
GENERALMETHOD
The hive used consisted of a tier of identical wooden chambers, each of which contained 11 frames for the combs. The chambers were enclosed by a roof on top and a floorboard below. One side of the floorboard was open to provide a hive entrance. An additional hive entrance was sometimes provided between two brood chambers by separating them with strips of wood, 20 mm wide along three sides leaving the fourth side open as the entrance (20 mm high and 450 mm long).
RESULTS
Experiment 1
The hive used in this preliminary experiment had four chambers arranged in a tier and two entrances. One entrance was in the usual position, just above the floorboard and below chamber 1. The other entrance was between chambers 3 and 4. A queen excluder (a sheet of zinc with slots through which the workers, but not the queen, could pass) separated chambers 2 and 3, so the queen was unable to leave the chambers with brood combs.
On June 20th all the combs containing brood were put in chambers 3 and 4, and chambers 1 and 2 contained only combs without brood. On June 26th, during three observation periods totals of 641 and 490 bees entered the upper and lower entrances, respectively, 49 and 33% of which had pollen loads (P < 0.001). During a single observation period on June 26th, 307 bees left and 213 entered (59% : 41%) the upper entrance, whereas 106 left and 194 entered (30% : 70%) the lower entrance (P < 0.001).
At 12.00 h on July 4th the positions of the chambers with and without brood combs were reversed so chambers 1 and 2 contained brood. On July 7th, during three observation periods, totals of 493 and 496 bees entered the upper and lower entrances respectively, but fewer of the former (29% : 53%) had pollen loads (P < 0.01).
Experiment 2
Two hives were used, each with four chambers and two entrances as in Ex- periment 1. On May 14th the combs of one hive, housing colony 176, were ar- ranged so that chambers 1 and 2 were without brood combs and chambers 3 and 4 contained brood combs. The other hive, housing colony 252, had brood combs in chambers 1 and 2, but no brood combs in chambers 3 and 4. In each hive a queen excluder separated chambers 2 and 3.
TABL
E I
Effe
ct
of l
ocat
ion
of e
ntra
nce
in r
elat
ion
to
broo
d on
the
pro
port
ion
of b
ees
colle
ctin
g po
llen.
R
esul
ts
for
the
entr
ance
ne
ares
t th
e br
ood
are
in i
tali
cs
--.
Col
ony
Dat
e En
tran
ce
that
w
as
Num
ber
of o
bser
vatio
n U
pper
en
tran
ce
Low
er
entr
ance
nu
mbe
r ne
ar
broo
d pe
riod
s /
252
1.6.
1973
7.
6.19
73
8.6.
1973
13
.6.1
973
176
1.6.
1973
7.
6.19
73
8.6.
1973
13
.6.1
973
.___
Lo
wer
Lo
wer
U
pper
U
pper
Upp
er
Upp
er
Low
er
Low
er
Tota
l nu
mbe
r of
Pe
rcen
tage
w
ith
Tota
l nu
mbe
r of
Pe
rcen
tage
w
ith
bees
ent
ered
po
llen
lo
ads
bees
ent
ered
po
llen
lo
ads
1 50
2 35
2
226
48
276
13
320
28
353
26
390
13
300
31
617
12
2 72
8 23
3
104
21
523
33
355
15
759
22
443
35
506
2 50
7 11
~.
__
144
On June 1st and 7th the bees with and withdut pollen loads that landed at the upper and lower entrances of each hive were counted during 5-min periods, observers watching either the lower or upper entrance of both hives simul- taneously. In the evening of June 7th, the positions of the chambers with and without brood combs in each hive were reversed and the observations repeated on June 8th and 13th. On June 7th, 8th and 13th the bees entering and leaving the hives during 5-min periods were also counted. The two entrances to each hive were watched simultaneously.
Pollen loads were present on a greater proportion of bees entering the lower than the upper entrance to colony 252, and the upper than the lower entrance to colony 176 (Table I): P < 0.05 and P < 0.001 for colony 176 on June 1st and 7th, respectively; P < 0.001 for colony 252 on both dates. Reversal of the chambers gave the opposite results (P < 0.001 for colonies 252 and 176 both on June 8th and 13th).
The proportion of bees that entered their colonies by the upper and lower entrances were similar (Table II). However, a greater proportion of bees left by the entrance adjacent to the brood (P <O.OOl, P < 0.001, P < 0.05, for colony 252 on June 7th, 8th and 13th, respectively; P < 0.001, for colony 176 on each day), particularly when the brood was near the lower entrance (i.e. colony 252 on June 7th, colony 176 on June 8th and 13th).
Experiment 3
On July 9th foragers entering colonies 176 and 252 with pollen loads were marked white and those without pollen loads were marked blue. The combs in the colonies were rearranged so that only the two lower chambers of colony 176 and the two upper chambers of colony 252 contained brood combs. In each colony a queen excluder was put between chambers 2 and 3.
The numbers of marked foragers (with and without pollen loads) were re- corded during a total of 15 5-min observation periods at each hive entrance
TABLE II
Effect of location of entranke in relation to brood on the proportion of bees entering and leaving it. Results for the entrance nearest the brood are in italics
Colony Date Entrance that was Number of observation Upper entrance number near brood periods
Number of bees Number of bees entered left _____.
252 7.6.1973 Lower 2 169 2 8.6.1973 Upper 2 158 216
13.6.1973 Upper 2 160 203
176 7.6.1973 Upper 2 127 152 8.6.1973 Lower 2 238 88
13.6.1973 Lower 2 256 14
145
between July 10th and 13th (Table III). Bees with pollen loads when marked, were more likely to be seen subsequently with pollen loads when using the entrance adjacent to the brood combs than when using the other entrance to their hive (P < 0.05 for combined results from colonies 176 and 252).Counts of unmarked foragers during four observation periods on July 13th (Table IV) confirmed that those that entered their hives near the brood combs also con- tained the greater proportion of pollen gatherers (P < 0.05 and P < 0.01 for colonies 176 and 252, respectively).
Experiment 4
In this experiment the behaviour of foragers from colonies with and without queen excluders was compared. On July 25th, foragers with and without pollen loads entering two colonies (246 and 252), each with four chambers and two entrances were marked white and blue, respectively. In the evening of July 25th all the brood combs of each colony were put in chambers 3 and 4. A queen ex- cluder separated chambers 2 and 3 (i.e. chambers with and without brood) in colony 252, but no queen excluder was used in colony 246.
During a total of 11 observation periods made between July 26th and August 8th, totals of 2 528 and 217 foragers (42 and 32% with pollen loads) entered the upper and lower entrances of colony 252, and 2 701 and 907 foragers (48 and 45% with pollen loads) entered the upper and lower entrances of colony 246. Hence, a larger proportion of foragers (P < 0.001) used the lower entrance in the colony without a queen excluder, and the proportion of bees with pollen loads was greater at the lower entrances of the colony without a queen excluder (P < 0.001).
In 11 other observation periods, the numbers entering and leaving each entrance were counted simultaneously. A total of 2 487 foragers entered and 2 042 left colony 252, 85 and 92% of them by the upper entrance. In com- parison, 2 945 foragers entered and 2 688 left colony 246 but relatively fevrer,
Lower entrance
Number of bees entered
178 247 138
126 115 236
Number of bees left
351 141 122
75 183 563
Percentage bees Percentage bees that left from that entered
Upper Lower Upper Lower - entrance entrance entrance entrance
1 99 49 51 61 39 39 61 62 38 54 46
67 33 50 50 32 68 67 33
2 98 52 48
TABL
E II
I
The
tend
ency
of
mar
ked
polle
n ga
ther
ers
to u
se h
ive
entr
ance
s ne
ar t
he b
rood
. R
esul
ts f
or t
he e
ntra
nce
of e
ach
hive
th
at w
as n
eare
st t
o th
e br
ood
are
in i
talic
s __
___-
, C
olon
y 17
6 C
olon
y 25
2 __
O
rigi
nal
beha
viou
r W
ith p
olle
n W
ithou
t po
llen
With
pol
len
With
out
polle
n lo
ads
load
s lo
ads
load
s En
tran
ce
subs
eque
ntly
ob
serv
ed a
t U
pper
Lo
wer
U
pper
Lo
wer
U
pper
Lo
wer
U
pper
Lo
wer
Num
ber
of b
ees
obse
rved
52
84
11
4 17
4 96
90
13
1 21
6 %
with
pol
len
load
s 15
29
5
5 52
38
10
6
TABL
E IV
Effe
ct
of l
ocat
ion
of e
ntra
nce
in r
elat
ion
to b
rood
in
the
pro
port
ion
of b
ees
colle
ctin
g po
llen
duri
ng f
our
obse
rvat
ion
peri
ods
on J
uly
13th
. R
esul
ts f
or t
he e
ntra
nce
near
est
the
broo
d ar
e in
ita
lics
Col
ony
num
ber
Upp
er e
ntra
nce
Low
er e
ntra
nce
Tota
l nu
mbe
r Be
es w
ith n
olle
n lo
ads
Tota
l nu
mbe
r Be
es w
ith n
olle
n lo
ads
bees
ent
ered
N
umbe
r Pe
rcen
tage
be
es e
nter
ed
Num
ber
Perc
enta
ge
~_
176
85
18
21
593
193
32
252
1 27
0 56
0 44
22
3 72
32
TABL
E V
Cons
tanc
y of
mar
ked
bees
to
uppe
r an
d lo
wer
ent
ranc
es
in c
olon
ies
with
and
with
out
a qu
een
exclu
der.
Bees
tha
t ke
pt c
onst
ant
to t
heir
entra
nce
are
in it
alic
s ._
__
__
__-.
.__
.~_
.~__
~_
. ~~
Orig
inal
beh
avio
ur
Entra
nce
at w
hich
su
bseq
uent
ly
obse
rved
Co
lony
25
2 (w
ith q
ueen
exc
lude
r) N
umbe
r of
bee
s ob
serv
ed
Colo
ny
246
(with
out
quee
n ex
clude
r) N
umbe
r of
bee
s ob
serv
ed
TABL
E VI
At
uppe
r en
tranc
e __
__
With
pol
len
With
out
polle
n lo
ads
load
s
Upp
er
Low
er
Upp
er
Low
er
.~~_
68
6 91
13
49
4 53
6
_~__
~.
At
low
er e
ntra
nce
With
pol
len
With
out
polle
n lo
ads
load
s
Upp
er
Low
er
Upp
er
Low
er
7 5
29
7
13
61
26
73
Cons
tanc
y of
mar
ked
bees
to
colle
ctin
g po
llen
in c
olon
ies
with
and
with
out
a qu
een
exclu
der
____
__
~_.
___~
___
___
~~ _
_ O
rigin
al b
ehav
iour
A
t up
per
entra
nce
At
low
er e
ntra
nce
With
pol
len
With
out
polle
n W
ith p
olle
n W
ithou
t po
llen
load
s lo
ads
load
s lo
ads
___.
__
~~ .~
~ ~_
~___
._
~
_ ~~
Co
lony
25
2 (w
ith q
ueen
exc
lude
r) N
umbe
r of
bee
s se
en
74
104
12
36
% w
ith p
olle
n lo
ads
74
30
33
6
Colo
ny 2
46
(with
out
quee
n ex
clude
r) N
umbe
r of
bee
s se
en
53
59
14
99
% w
ith p
olle
n lo
ads
77
42
73
12
~~~
---.
~ --
_ __
~ ~_
_ .___
-.
148
73 and 70% (P < 0.001 and P < 0.001, respectively) by the upper entrance. The marked bees were observed for ten observation periods at each entrance
between July 26th and August 8th. Most bees of both colonies that were marked at the upper entrance kept constant to it (Table V). However, more bees marked at the lower entrance to colony 246 (without the queen excluder) kept constant to their lower entrance than bees marked at the lower entrance of colony 252 (P < 0.01 and P < 0.001 for bees marked with and without pollen loads, respectively) most of which changed to the upper entrance.
There was no difference between colonies in the proportions of bees, origi- nally using the upper entrance, that collected pollen (Table VI), but bees origi- nally with pollen loads and using the lower entrances of colony 252 (with a queen excluder) were much less inclined to collect pollen than those using the lower entrance of colony 246 (P < 0.02). In 11 observation periods the marked bees leaving the upper and lower entrances of each colony were simultaneously counted. Only five of 135 (4%) marked bees that left colony 252 did so from the lower entrance, whereas, of 168 marked bees that left colony 246, a total of 71 (42%) did so by the lower entrance (54 of them had been marked at the lower entrance).
Experiment 5
The effect of queen excluders on the distribution of foragers throughout a hive was determined. Two hives were arranged so that the two upper chambers of each contained brood combs and the two lower chambers of each, below which was the only entrance, contained no brood. Colony 252 had a queen ex- cluder between chambers 2 and 3. Colony 246 had no queen excluder.
On August 9th foragers that returned to the hives were marked with differ- ent colours indicating whether or not they had pollen loads. On three occasions between August 10th and 20th while the colonies were foraging, the hives were examined and the positions of the marked foragers within them were recorded.
The two upper chambers of colony 252 (with a queen excluder) contained a total of only 17 (7%) of the 246 marked bees present, whereas the two upper chambers of colony 246 contained 75 (56%) of the 133 marked bees. The bees in the upper chambers contained a greater proportion of the original pollen gatherers than the bees in the lower chambers (71% : 51% for colony 252; 37% : 29% for colony 246).
Experiment 6
On July 9th the lower chamber of a hive was divided by a wooden partition into two equal parts, each with five combs. Separate entrances to the two parts were provided at opposite sides of the chamber. One entrance had a yellow alighting board, the other a blue one. A chamber containing combs without brood was situated immediately above the lower chamber. This was followed by a queen excluder and a chamber with brood combs and the queen.
TAB
LE
VII
Effe
ct o
f lo
cati
on
of e
ntra
nces
in
the
low
er c
ham
ber
in r
elat
ion
to t
he p
rese
nce
of b
rood
ne
arby
on
the
prop
orti
on
of b
ees
colle
ctin
g po
llen.
Res
ults
for
the
ent
ranc
e ne
ares
t to
the
bro
od a
re i
n ita
lics
Dat
e
July
12t
h Ju
ly 1
3th-
20th
Ju
ly 3
0th
Aug
ust
1st~
8th
Ent
ranc
e ne
ar
Blu
e en
tran
ce
to t
he b
rood
To
tal
num
ber
Bee
s w
ith
polle
n lo
ads
of b
ees
ente
red
Num
ber
Perc
enta
ge
_~
__
Nei
ther
63
4 11
3 18
Ye
llow
16
87
497
29
Nei
ther
42
4 96
23
B
lue
803
299
37
Yello
w
entr
ance
Tota
l nu
mbe
r B
ees
wit
h po
llen
load
s of
bee
s en
tere
d N
umbe
r Pe
rcen
tage
200
20
10
710
282
40
499
139
28
493
102
21
TAB
LE
VII
I
Effe
ct o
f th
e ty
pe o
f hi
ve e
ntra
nce
on t
he b
ehav
iour
of
bees
on
ente
ring
the
ir h
ives
._
__
-. Ty
pe o
f hi
ve
Num
ber
of o
bser
vati
ons
entr
ance
pe
r co
lony
____
...__
__
._~
Low
(50
X
12 m
m)
5 H
igh
(50
x 12
mm
) 5
Low
(5O
x 6m
m)
3 H
igh
(50
x 6
mm
) 3
____
-..
___
_~_.
. __
_~
__
Tota
l nu
mbe
r of
bee
s %
bee
s w
ith
polle
n -_
_.
____
____
W
alke
d al
ong
Wal
ked
up i
nsid
e W
alke
d al
ong
Wal
ked
up i
nsid
e of
flo
or
of f
ront
wal
l of
hiv
e flo
or
fron
t w
all
of h
ive
~.__
__.
__-_
_ 13
35
(42%
) 1
801
(58%
) 35
56
11
39
(42%
) 1
565
(58%
) 34
57
10
05
(60%
) 67
1 (4
0%)
40
59
353
(12%
) 1
764
(88%
) 30
65
_I
. ~.
~~
_..
~._.
__.
-. __
-. 2 (D
150
In the evening of July 12th the five combs from the yellow side of thelower chamber were exchanged for five brood combs from the top chamber. The be- haviour of foragers was recorded during nine observation periods between July 13th and 20th (Table VII). In the evening of July 20th the brood combs in the yellow side of the lower chamber were returned to the top chamber.
In the evening of July 30th the five combs in the blue side of the lower brood chamber were exchanged for five brood combs from the top chamber, and the behaviour of foragers was recorded during six observation periods between August 1st and 8th (Table VII). The proportion of foragers with pollen loads was greater at the yellow entrance from July 13th to 20th (P < 0.001) and at the blue entrance from August 1st to 8th (P < 0.001). Re- lative to the control observation periods on July 12th and 30th when there was no brood in the lower chamber, the proportion of foragers with pollen loads increased at the yellow entrance during July 13th-20th (P < 0.001) and at the blue entrance during August lst-8th (P < O.OOl), respectively.
Experiment 7
The floorboards of four hives were replaced with glass, and were otherwise identical with normal ones. By lying on his back under such a hive an observer was able to determine the route taken by bees when they entered the hive. Each hive was observed in turn for 5min periods. The hive entrances were either:
(a) A “low” central, 50 mm long and 12 mm high, whose base was level with the floorboard.
(b) A “high” central, 50 mm long and 12 mm high, whose base was 8 mm above the level of the floorboard and whose top was formed by the lower brood chamber.
(c) A “low” central, 50 mm long and 6 mm high, whose base was level with the floorboard.
(d) A “high” central, 50 mm long and 6 mm high, whose base was 14 mm above the level of the floorboard, and whose top was formed by the lower brood chamber.
After each observation on a colony, its hive entrance was changed and the colony not observed again until the next day.
On entering their hive the returned foragers either walked up the inside front wall of their hive and so on to the comb, or else walked along the floorboard until they could reach up to one of the combs. Because the floorboard sloped downward toward the entrance, the distance between the floorboard and the base of the frames increased toward the front of the hive. Thus a returning forager has difficulty in reaching the combs until it has moved some way from the entrance. The presence of clusters of bees on the bases of the frames re- duced the distance the bees must have reached to gain access to the combs. Whatever the type of restricted entrance, the bees that walked up the inside of the front wall of the hive included a greater proportion of pollen gatherers
151
(P < 0.001 for each comparison) than those that walked along the floorboard (Table VIII). A low entrance of 50 X 6 mm caused an increased proportion of bees to walk along the floorboard, and a high entrance of 50 X 6 mm caused an increased proportion of bees to walk up the front wall.
On half the occasions that colonies were watched, the combs were parallel to the entrance, and on the other half, they were at right angles to the entrance, but this made no apparent difference to the bees’ behaviour.
Experiment 8
Two colonies were each given a glass floorboard and the combs in their lower chambers were arranged so that they were at right angles to the hive entrance and those combs that contained brood were together at one side of the hive. One colony had six combs with brood and five combs without. The other colony had five combs with brood and six combs without. The combs were numbered on the bases of their frames, so they could easily be identified by an observer watching from beneath the glass floorboard. During ten observation periods on each colony the number of returned foragers that went to each comb was recorded. Totals of 503 and 195 bees went to combs with and with- out brood, respectively, and 38 and 17% of them had pollen loads. Hence, more bees, and a greater proportion with pollen loads (P< 0.001) went to the combs with brood.
Experiment 9
The combs in the lower chamber of each of three colonies (A, B and C) were arranged so that combs 5,6 and 7 contained young brood, and the other combs none. All combs were at right angles to the hive entrance. Observers beneath the glass floorboards selected, at random, individual foragers that walked along the hive floor and watched them continuously to find to which comb they went (Table IX). Each colony was observed for a 15-min period at a time. For the first two observation periods the entrance to each colony was unrestricted. For the second two observation periods the entrance was restricted to a central area of 50 X 20 mm. In the final two observation periods the same restricted entrance was used but it was prolonged as a “tunnel” into the hive with two pieces of wood (100 mm long) placed at right angles to the entrance and either side of it.
The proportion of bees that went to combs 5,6 and 7 was increased by: using the restricted entrance, without tunnel, instead of an unrestricted en- trance (all foragers P < 0.02, bees with pollen loads P < 0.05); using a restricted entrance with tunnel instead of an unrestricted entrance (all foragersP< 0.001, bees with pollen loads P < 0.001, bees without pollen loads P < 0.001); using a restricted entrance with tunnel instead of a restricted entrance without tunnel (all foragers, P < 0.001, bees with pollen loads P < 0.001, bees without pollen loads P < 0.01).
152
TABLE IX
Effect of type of hive entrance on the number of foragers that went to combs with and without brood. Results for combs with brood are in italics. All combs at right angles to entrance
5Pe of entrance
Colony Combs 1 to 4, Combs 5 to 7, without brood with brood
Unrestricted
Restricted
Restricted with tunnel
With Without With pollen pollen pollen loads loads loads
3 14 25 3 18 13 5 13 7
11 45 45
1 6 21 I 9 19 1 8 14 9 23 54
2 5 17 a 6 39 5 8 17 7 19 73
Without pollen loads _ 10 12 10 32
11 20 11 42
16 41 15 72
Combs 8 to 11. without brood _ With Without pollen pollen loads loads
12 6 3 4 0 1
15 11
8 8 2 5 0 1
10 14
1 3 0 3 2 1 3 7
Experiment 10
The combs in the three hives used were parallel to the hive entrance. As be- fore, observers determined to which combs returning foragers went (Table X). In the first two 15min observation periods on each colony only the third comb from the entrance contained brood. In the second two observation periods the situation was the same except that a strip of wood, 5 mm high, 12 mm wide, 450 mm long had been put on the floorboard directly beneath the third comb. In the third two observation periods the fourth comb also contained brood. In the last two observation periods only the second comb contained brood and the strip of wood was put directly beneath it. The use of strips of wood under combs 2 and 3 increased greatly the proportion of returned foragers that went to them (P < 0.001 for each comparison).
DISCUSSION AND CONCLUSIONS
Using two entrances, the lower adjacent to brood combs and the upper ad- jacent to storage combs should discourage the undesirable deposition of pollen loads in storage comb from which honey is to be extracted. The use of a queen excluder, which hampers the movement of bees through the hive, should re- inforce this tendency. To stimulate maximum pollen collection and pollination, however, it is important that the one or both entrances to a hive lead directly to nearby brood. Although a strong colony in summer usually has enough brood to ensure that all the combs in one chamber contain brood, a weak
TAB
LE
X
Att
empt
s to
ind
uce
fora
gers
to
go t
o pa
rtic
ular
com
bs
by p
laci
ng s
trip
s of
woo
d on
the
flo
or
bene
ath
them
. R
esui
ts f
or c
omb
wit
h st
rip
of w
ood
bene
ath
are
in i
talic
s. A
ll co
mbs
pa
ralle
l to
ent
ranc
e. a
, bee
s w
ith
polle
n lo
ads;
b,
bees
wit
hout
pol
len
load
s
Stri
p of
B
rood
C
olon
y N
umbe
r of
bee
s th
at w
ent
to c
omb
num
ber
1 2
3 6
woo
d pr
esen
t un
der
com
b nu
mbe
r
Non
e
in c
omb
num
ber
a b
a b
a b
4 5
a b
a b
a b
3 A
1
1 7
8 4
B
4 6
9 3
6 C
0
2 2
9 3
All
5 7
18
20
13
-__-
3 2 10
15
3
-
A
B C
All A
B C
All A
B C
All
0 1
1 2
8 3
5 6
5 2
14
13
1 1
7 3
7 16
6
7 13
7
29
32
3 an
d 4
0 2
1 1
0 0
1 3
3 5
0 0
1 2
4 7
1 3
0 5
0 1
1 9
7 20
4
I8
5 8
16
46
14 5 16
35 0 0 0 0
17 8 14
39 0 0 0 0
0 2
0 3
1 1
0 2
1 3
4 2
0 0
0 0
0 0
0 2
0 0
2 0
6 6
0 0
0 0
3 3
0 9
9 0
0 0
0 0
0 0
0 0
0 0
0 0
0 2 1 3 0 0 1 1 0 0 0 0 0 0 0 0
0 2 0 2 0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 2 0 0 0 0 0 0 0 0 0 0 0 0
154
colony, or one in spring that has not reached its brood rearing potential, often does not rear brood in combs near the hive entrance. In such circumstances the proportion of foragers visiting the brood area would be increased by directing them first along the floor of the hive, by using a shallow entrance flush with the floorboard, and then on to the brood combs by extending the entrance as a tunnel when the combs are at right angles to it and by using narrow strips of wood immediately under the brood combs when they are parallel to it. These strips would need to have channels through which bees could remove any debris that fell on the rear part of the floorboard. While in the brood area of a colony, foragers will also be in the vicinity of their queen whose presence, even without brood, stimulates workers to forage (Free and Preece, 1969; Free and Williams, 1972) and to deposit their pollen loads (Free and Williams, 1974). Hence, by using such minor and inexpensive adaptations the value of honeybee colonies as pollinators should be greatly increased.
REFERENCES
Free, J.B., 1967. Factors determining the collection of pollen by honeybee colonies. Anim. Behav., 15: 133-144.
Free, J.B., 1970. Insect Pollination of Crops. Academic Press, London, 544 pp. Free, J.B., 1971. Management of honeybee colonies for crop pollination. In: Rep. Rotham-
sted Exp. Stn for 1970, Part 2, pp. 184-198. Free, J.B. and Preece, D.A., 1969. The effect of the size of a honeybee colony on its foraging
activity. Insectes Sot., 16: 73-78. Free, J.B. and Williams, I.H., 1971. The effect of giving pollen and pollen supplement to
honeybee colonies on the amount of pollen collected. J. Apic. Res., 10: 87-90. Free, J.B. and Williams, LH, 1972. Hoarding by honeybees (Apis mellifera L). Anim. Behav.,
20: 327-334. Free, J.B. and Williams, I.H., 1973 a. The pollination of hybrid kale (Brassica oleraceae L).
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honeybee (Apis mellifera L) comb. J. Entomol. Ser. A, 49: 47-63. Jaycox, E.R., 1970 a. Honeybee queen behaviour and worker foraging behaviour. Ann.
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extracts of larvae. Ann. Entomol. Sot. Am., 63: 1689-1694. Todd, F.E and Reed, C.B., 1970. Brood measurement as a valid index to the value of
honeybees as pollinators. J. Econ. Entomol., 63: 148-149. Williams, I.H. and Free, J.B., 1974. The pollination of onion (Allium cepa L) to produce
hybrid seed. J. Appl. Ecol., 11: 409-418.