AGE OF NURSE BEES AND BROOD REARINGe

f.,
nted from Journal of Apicultural Research 2(2) : 101-103 (1963) i
101
AGE OF NURSE BEES AND BROOD REARINGe
-—
MYKOLA H. HAYDAK
Dept. Entomology, Fisheries & FVildlife, University of Minnesota., Si. Paul 1,
Minnesota, U.S.A.
Manuscript received for publication 2nd lune
1963
SUMMARY
Nurse becs were forced to rear brood continuously, under field and laboratory conditions. The
weight and the length of life of the becs they reared decreased when the nurse bees were much older than
is normal (40-98 days instead of 5-16 days). Intestines of emerged becs reared by nurse becs 50 days old
and more were very fragile. In the control colonies these phenomena were flot observed.
INTRODUCTION
The question whether old bees (Apis mellifera) can still rear brood has a considerable
biological interest. However, only a few publications have dealt with this problem.
Kramer (1896), Peterka (1928), Haydak (1930) and Jordan (1963) by their experiments
answered this question affirmatively. Milojevic (1940) and Buchner (1953) also showed
that the reduced hypopharyngeal glands were restored to full activity when old bees
were forced to rear brood.
The present work was undertaken to find out how long worker bees can rear brood
if forced to do so, and to what an extent workers produced by the aging nurse bees differ
in their weight on emergence, and their length of life, from those produced by normal
colonies of becs under both field and laboratory conditions.
EXPERIMENTS
Field studies
Three very strong colonies of bees were selected in the apiary. The brood combs
from each colony, with the adhering bees but without the queen, were transferred to new
hives. The three daughter colonies thus formed were taken to a secluded location in
order to prevent any bees of unknown age entering the hives. The `mother' colonies with
the queens and enough room for egg laying were left on on the original sites and served
as controls.
Ten days after this operation, the combs with the brood were removed from the
experimental (daughter) colonies, empty combs substituted, and the queens from the
mother colonies then introduced. The brood combs removed were placed at the top
of the control colonies. As soon as the first sealed worker cells were noticed in the
experimental colonies the queens were again removed to the control colonies. Nine
days later the brood combs were again taken out, enough worker combs substituted,
and the queens reintroduced. These procedures were continued as long as the becs were
able to rear brood, or until the weather prevented continuation.
* Paper No, 5122 Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul 1,
Minnesota
102
The procedure of handling the control colonies was similar to that described for
the experimental colonies. The brood combs taken out from the experimental colonies
were placed at the top of these hives, thus maintaining a normal composition of the
worker force in the control colonies. No bees were allowed to emerge in the experimental
colonies, thus maintaining the original population of bees, which became progressively
older.
Laboratory studies
Simultaneously, four colonies consisting of about 800 g. freshly emerged bees
each were estabfished in cages in the laboratory. Fertile laying queens were introduced
to each of them, and the bees were given pollen candy (105 g. pollen 25 c.c. water
± 40 g. honey, mixed together), sugar solution and water ad libitum. Their management
was similar to that followed with the experimental colonies out of doors.
Every time the combs were removed from the field and laboratory colonies, several
of them were taken to the constant-temperature chamber (35°C.) and 50 freshly emerged
becs taken for dissection. The heads, abdomens without digestive tracts, and thoraces,
were separated, weighed and dried to constant weig,ht-in a drying oven at 102°C.
RESULTS
The numerical results are presented in Table 1. There was a general decrease in the
weig,ht of ail parts of becs in the experimental colonies, whereas those of the c,ontrols
remained practically unchanged. More marked decreases occurred under laboratory
conditions. The intestines of emerging becs produced by nurses of 50 days and more
were very fragile; almost every one broke and had to be pulled out of the abdomen with
forceps. Some broke as many as three times. In colonies vvith nurse bees 30 days old and
more, the larval food had a watery consistency and appeared to be flot as milky as normal.
TABLE
Date
Contrai colonies
26/27 July
9-11 Aug.
29 Aug.
16-19 Sept.
1. Weig,ht of emerging bees
Age of
nurse bees
in days
normal
normal
normal
normal
•.
..
..
..
Average dry weight per bee (mg.)
Head
Abdomen
Thorax
Whole bee
..
..
..
..
2-4
2.5
2.5
2.4
3.0
3.0
2.9
2.8
9.6
9.4
9-5
15-0
14-9
14-7
Experimental colonies
In the field
12-16 July
1-3 Aug.
16-18 Aug.
31 Aug.-6 Sept.
25-26 Sept.
normal
..
15-17 and more
31-35 and more
46-50 and more
71-73 and more
..
..
..
..
..
2-4
24
2.2
2.3
2-1
2-8
2-8
2.7
2-6
2.5
9•3
9.1
8.5
8-6
8-4
14.5
14.3
134
13-5
13.0
18 July-3 Aug.
5-17 Aug.
27 Aug.-13 Sept.
21-29 Sept.
8-18
27-34
47-55
69-74
..
..
..
..
2-3
2.2
2-0
2-0
2.9
2-6
2.4
2.5
9.2
8.4
7.7
7.5
144
13.2
12-1
12-0
In the laboratory
The food was flot assayed; very little of it was present in the cefis. However, observations
under a dissecting microscope showed that the hypopharyngeal glands of 70 % of the
103
nurse bees 79-83 days old were fully active. In only 13 % of these bees was the lumen of
the mandibular glands full of milky secretion; in the rest it was in the vacuolated stage
(see Haydak, 1957). In another set of experiments the bees continued to rear brood
until they were 138 clays old, though the number of sealed cells was rather small. Nevertheless, even at that time 18 % of the examined bees had fully active hypopharyngeal
glands; in 72 % the glands had started to degenerate, but only in 10% had they degenerated completely. On the other hand, only 10% of the dissected bees had active mandibular glands; 90% were in a vacuolated stage.
In order to find out what influence the age of the nurses has on the length of life
of the bees they rear, every time the combs with sealed brood were placed in the incubator, two groups of freshly emerged bees were placed in small cages and offered sugar
solution and water ad libitum. Their daily mortality was established (Table 2).
TABLE 2. Mortality of emerged becs
Date
Contrai
4 Aug.
25 Aug.
14 Sept.
3 Oct.
Total weight of
When ha!! the
ail emerging bees becs were dead
(days)
(g.)
Age of
nurse bees
in days
normal . .
normal ..
normal ..
normal ..
..
..
..
..
63
54
51
40
zo
14
16
18
35
31
35
33
70
63
42
36
39
13
15
13
9
12
35
25
26
27
24
Experimental
21-29 July
15 Aug.
5 Sept.
23 Sept.
12 Oct.
16
..
..
61
79
98
..
..
..
..
..
..
ao
..
When ail the
becs were dead
(days)
..
The length of life of bees dimini shed as the age of their nurses increased. This was
not so in the control colonies, where the longevity of emerged becs remained about the
same throughout the duration of the experiment.
It appears that nurse becs can rear brood for a considerable period of their lives;
the becs reared by old nurses are however of a lower weight, inferior in the strength
of their tissues, and shorter-lived.
REFERENCES
BUCHNER, R. (1953) Beeinflüssung der Grosse der Arbeitsbiene durch Raum- und Nahrungsmangel
wâhrend der Larvenzeit. Roux' Arch. EntwMech. 146 : 544-579
H. (1930) 0 d'élbé prâce ve ve'elstvu za abnormalnIch okolnosti Éeski Véeltue 64(5) : 166168 ; Division of labor in the bec colony under abnormal conditions. Wisc. Beekeep. 8(5) : 36-39
(1932)
— (1957) Changes with age in the appearance of soma internai organs of the honeybee. Bec World
38(8) : 197-207
JORDAN, R. (1963) Ueber die abermalige Entfaltung—Regeneration der Futtersaftdrüsen bei Flugbienen.
Bienenvater 84(1) : 3-9
KaAmaa, U. (1896) Sind alte d.h. Trachtbienen n'eh fâhig zu brüten ? Schweiz. Bienenztg 19 : 64-70
Mmonvic, B. D. (1940) A new interpretation of th?, slcial life of the hpney bec. Bec World 21(4) : 39-41
PETERICA, V. (1928) Krmeni plodu starSemi vêelami. Éeski Véelaf 62(11) : 312-313
HAYDAR, M.