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Does kin recognition in honey bees, Apis mellifera L., influence the workers' chances of becoming egg layers?
Anim. Behav., 1991, 42, 867-870
Does kin recognition in honey bees, Apis meilifera L., influence the workers ~ chances of becoming egg layers? JAN VAN DER BLOM & ARIE-JAAK VERKADE Laboratory o f Comparative Physiology, University of Utrecht, P.O. 80086, 3508 TB Utrecht, The Netherlands
(Received 29 November 1990; initial acceptance 20 February 1991; final acceptance 25 March 1991; MS. number: sc-618)
Various studies have shown that, under a variety of circumstances, worker honey bees behave differently towards nestmates of their own patrilines (full sisters) than towards nestmates of other patrilines (half sisters). However, the significance of this is still disputed (e.g. Carlin 1989; Carlin & Frumhoff 1990; Grafen 1990). Workers may enhance their fitness in two different ways. First, they may discriminate between closely or less closely related larvae when rearing new queens or drones. Page & Erickson (1984), Noonan (1986) and Visscher (1986) found a positive discrimination in favour of related brood in queen rearing when workers were given the opportunity to choose from eggs. These biases in favour of close kin were small, varying from 1-2 to 1-6:1 (averaged over many experimental colonies). However, Woyciechowski (1990) could not confirm this in similar experiments. No discrimination has been found where young larvae (in royal jelly) were introduced, not even when the workers were offered a choice between brood of different races (Breed et al. 1984; Visscher 1986). Furthermore, no nepotistic discrimination occurred in cases of emergency queen rearing (Breed et al. 1984; Page & Erickson 1986). Page et al. (1989) claimed to have found nepotism in queen rearing among subfamilies within colonies, but their experimental design and their statistical analysis have been severely criticized by Carlin & Frumhoff (1990) and Oldroyd et al. (1990). Altogether, the evidence for kin discrimination in the rearing of queens is not very strong. As far as we know, there are no reports of nepotistic discrimination of drone larvae. The second way by which individual bees could increase their fitness is by becoming egg layers in the absence of the queen. This can be achieved only by a small percentage of the workers who depend on interactions with other workers in the colony: they have to receive important proteins from 0003 3472/91/110867+04 $03.00/0
other workers and may be attacked (and killed or damaged) by other workers (Sakagami 1954; Velthuis 1985; van der Blom, in press). In colonies with a mixture ofpatrilines, workers should receive more support or experience less competition from full sisters than from less related workers if kin recognition cues play a role. Several papers suggest that this is indeed the case (Evers & Seeley 1986; Frumhoff & Schneider 1987). Thus, for an individual worker, the chances of becoming an egg layer should depend on the composition of the colony. This has hardly ever been investigated directly. Page & Erickson (1988) found indications that drones produced by workers do not originate primarily from the numerically dominant subfamilies. However, they could not tell exactly how many drones had been produced by each of the two subfamilies, and their results may have been influenced by unknown factors linked to the genetic marker (the cordovan locus) they used to distinguish between the patrilines (the bees with the cordovan locus always dominated drone production). The purpose of our experiment was to study the development of egg layers in orphaned colonies in two situations: one where a group of workers finds itself among a large majority of (half-) sisters and the other where workers are surrounded only by a minority of relatives. We used the size of the ovaries as a measure of reproductive potential. If nepotistic discrimination during interactions between adult workers is ultimately important, we predict that workers from the first group would have better developed ovaries than workers from the latter group. To avoid possible artefacts related to introduction of marker phenotypes (Carlin & Frumhoff 1990) and to the use of a very small number of patrilines (Hogendoorn & Velthuis 1988), we used indistinguishable bees of the same race, Apis m. mellifera, and a natural number of patrilines.
9 1991 The Association for the Study of Animal Behaviour 867
868
Animal Behaviour, 42, 5
Queenless colonies of about 2000 workers, without brood, were taken from queenright 'mother colonies' (i.e. colonies with a queen) and installed in six-frame beehives. Half of these mother colonies were bought from a beekeeper living about 100 km away. The bees from the imported colonies were completely unrelated to the ones from our own apiary. Six pairs of unrelated queenless colonies were formed in 1989. The first three pairs were installed on 17 May, the next three pairs on 20 June. Frames of closed brood from each of the queenright 'mother colonies' were placed in an incubator at 33~ Newly eclosed bees were paint-marked according to their origin. A hundred bees of both the colony of origin and of the non-related 'partner colony' were introduced at the same time into each queenless beehive, 2 days after the queenless colonies were installed (19 May and 22 June). Thus, the bees introduced from the colonies of origin found about 2100 relatives among the bees in the hive, whereas the bees introduced from another colony had only about 100 relatives. When a significant number of worker eggs were found in the colonies (2 June and 14 July), the bees were collected and put into a freezer at -20~ The size of the ovaries of all marked individuals that were recovered was determined. For simplicity, we divided the bees into two groups, the bees with small ovaries (Velthuis 1970: stage A-D) and the bees whose ovaries contained developed eggs (E-H). Since age-related factors are very important in the development of laying workers, unmarked workers (of unknown age) could not provide control data on development of the ovaries. We therefore present data only on the workers that were marked. (Since many authors have studied behaviour of paint-marked bees in observation hives and there are no reports that the paint itself influences the bees in interactions, we assume that the paint does not have any influence on our results.) It should be noted that if we find any differences between the development of related or unrelated workers in the hive, we will not be able to conclude that this is completely due to kin recognition. This experiment does not preclude possible forms of inter-colony nest-mate recognition. However, if there are no differences, we can conclude that kin recognition does not seem to influence development of the ovaries. Table I shows the distribution of the workers recovered by the end of the experiment according to
the development of their ovaries. First, we compare the number of recovered workers, without taking into account the development of the ovaries. A Wilcoxon signed-rank test showed that, per experimental hive, there was no systematic difference between the number of recovered workers that were related or unrelated to the majority of the bees in the hive (in Table I comparing 36 with 41, 45 with 47, etc.: Ts=23, N = 12, P>0.05). If we compare the number of workers surviving from one colony of origin that were introduced into colonies with related or unrelated workers (i.e. 36 with 47, 41 with 45, etc.), we do not find any significant difference either (Ts=33.5, N = I 2 , P>0.05). We do not know what happened to the workers that were not recovered. Some may have shifted to other colonies and some will have lost their paint mark. These factors, however, do not seem to depend on the relative degree of relatedness to the bees in the hive, since we found no differences in survival. Three variables may influence the development of ovaries: (l) being related or not to the majority of the bees in the hive; (2) genetically or phenotypically acquired characters related to the origin of the bees; (3) physical conditions in the hive in which the experiment took place. It will never be possible to rule out the second and third factors. It is known that there may be big differences in the reproductive potential between bees of different colonies, based on their genetic and physiological background. By comparing bees from different origins, this cannot be standardized. Furthermore, we know that the situation in the experimental hive (e.g. the amount of food present, the presence of brood, etc.) is of major influence for the actual development of laying workers (this effect was minimized by standardizing the experimental set-up as much as possible). The effects of each of these three variables upon the ovary size were analysed with a logistic regression test (Engelman 1985; Freeman 1987). In this test, the possible (independent) sources of variation were separated to find out which one(s) may explain the observed differences in development of the ovaries ( = the dependent variable). The results are: being related or not to the majority of the bees: ~2=0.877, df= 1, P=0.349; origin of the bees: Z2=16.79, d f = l l , P=0.114; hive in which the experiment took place: ;(2=25.45, df= 11, P = 0-008. This means that the development of the ovaries is influenced primarily by the different situations in the experimental hives and not by the physical or
Short Communications
869
Table I. The development of the ovaries of workers introduced into related or non-related queenless colonies
Total no. recovered Experimental hive
Colony of origin
Related
1 1
1 2
36
2 2
2 1
45
3 3 4 4
3 4 4 3
44
5 5 6 6
5 6 6 5
72
7 7 8 8
7 8 8 7
19
9 9 10 10
9 10 10 9
18
11 11 12 12
11 12 12 11
31
Total
Related Unrelated
Ovaries small
Unrelated
Related
Unrelated
Ovaries large Related
27
41
9
33 42
47 26
10 32
18 30
39
33
20
11
0
0
23
12
20
11 2
18 15
19
2 4
19 22
28
0 9
27 21
34
1 2
27 269
genetic differences connected with the origin o f the bees. These factors were n o t specifically examined. W h e t h e r the introduced bees are strangers or relatives does not have a significant effect o n ovarian development. In o u r experiment we f o u n d n o differences in either the rate of survival, or the n u m b e r of bees t h a t developed into laying workers w h e n comparing the bees that were or were n o t s u r r o u n d e d by a majority of related workers. Therefore, we can conclude t h a t so far there is n o evidence t h a t nepotistic discrimination in interactions of w o r k e r h o n e y bees leads to different chances o f r e p r o d u c i n g in n a t u r a l situations. W e t h a n k H a y o Velthuis, J a n v a n Hooff, K a t j a H o g e n d o o r n and Steven K o l m e s for their suggestions d u r i n g the research a n d their c o m m e n t s o n the m a n u s c r i p t a n d D r J. A. J. F a b e r for helping with the statistical analysis. Miss S. M. M a c N a b
0 6
16
355
9 11
14
351
6 6
8
23
2 8
8
19
23 4
64
20
10
29 6
14
8
3 37
52
Unrelated
7 82
276
79
is t h a n k e d for giving linguistic advice. D r M. Woyciechowski a n d a second ( a n o n y m o u s ) referee gave valuable c o m m e n t s o n the manuscript. The investigations were s u p p o r t e d by the F o u n d a t i o n for Biological Research (BION).
REFERENCES
van der Blom, J. In press. Social regulation of egg-laying by queenless honeybee workers (Apis mellifera L.). Behav. Ecol. Sociobiol. Breed, M. D., Velthuis, H. H. W. & Robinson, G. E. 1984. Do worker honeybees discriminate between unrelated and related larval phenotypes? Ann. entomol. Soc. Am., 77, 737 739. Carlin, N. F. 1989. Discrimination between and within colonies of social insects: two null hypotheses. Neth. J. Zool., 39, 86-100. Carlin, N. F. & Frumhoff, P. C. 1990. Nepotism in the honeybee. Nature, Lond., 346, 70(%707.
870
Animal Behaviour, 42, 5
Engelman, L. 1985. Stepwise-logistic regression. In: BMDP Statistical Software (Ed. by W. J. Dixon), pp. 330-344. University of California Press. Evers, C. A. & Seeley, T. D. 1986. Kin discrimination and aggression in honey bee colonies with laying workers. Anim. Behav., 34, 924-925. Freeman, D. H. 1987. AppliedCategoricalDataAnalaysis. New York: Marcel Dekker. Frumhoff, P. C. & Schneider, S. 1987. The social consequences of honey bee polyandry: the effects of kinship on worker interactions within colonies. Anim. Behav., 35, 255-262. Grafen, A. 1990. Do animals really recognize kin? Anim. Behav., 39, 42 54. Hogendoorn, K. & Velthuis, H. H. W. 1988. Influence of multiple mating on kin recognition by worker honeybees. Naturwissenschaften, 75, 412-413. Noonan, K. C. 1986. Recognition of queen larvae by worker honeybees (Apis mellifera). Ethology, 73, 295-306. Oldroyd, B. P., Rinderer, T. E. & Buco, S. M. 1990. Nepotism in the honeybee. Nature, Lond., 346, 707-708. Page, R. E., Jr & Erickson, E. H. 1984. Selective rearing of queens by worker honeybees: kin or nestmate recognition. Ann. entomol. Soc. Am., 77, 578 580.
Page, R. E., Jr & Erickson, E. H., Jr. 1986. Kin recognition during emergency queen rearing by worker honeybees (Hymenoptera: Apidae). Ann. entomol. Soc. Am. 79, 460-467. Page, R. E., Jr & Erickson, E. H., Jr. 1988. Reproduction by worker honeybees (Apis mellifera L.). Behav. Ecol. Sociobiol., 23, 117-126. Page, R. E., Robinson, G. E. & Fondrk, M. K. 1989. Genetic specialists, kin recognition and nepotism in honeybee colonies. Nature, Lond., 338, 576-579. Sakagami, S. F. 1954. Occurrence of an aggressive behaviour in queenless hives, with considerations on the social organisation of honeybee. Insectes soc., 1, 331 343. Velthuis, H. H. W. 1970. Ovarian development in Apis mellifera worker bees. Ent. exp. appl. 13, 377-394. Velthuis, H. H. W. 1985. The honeybee queen and the social organisation of her colony. Fortschr. Zool., 31, 343-357. Visseher, P. K. 1986. Kinship discrimination in queen rearing by honeybees (Apis mellifera). Behav. Ecol. Soeiobiol., 18, 453-460. Woyciechowski, M. 1990. Do honeybee, Apis mellifera L., workers favour sibling eggs and larvae in queen rearing? Anim. Behav., 39, 1220 1222.
Does kin recognition in honey bees, Apis meilifera L., influence the workers ~ chances of becoming egg layers? JAN VAN DER BLOM & ARIE-JAAK VERKADE Laboratory o f Comparative Physiology, University of Utrecht, P.O. 80086, 3508 TB Utrecht, The Netherlands
(Received 29 November 1990; initial acceptance 20 February 1991; final acceptance 25 March 1991; MS. number: sc-618)
Various studies have shown that, under a variety of circumstances, worker honey bees behave differently towards nestmates of their own patrilines (full sisters) than towards nestmates of other patrilines (half sisters). However, the significance of this is still disputed (e.g. Carlin 1989; Carlin & Frumhoff 1990; Grafen 1990). Workers may enhance their fitness in two different ways. First, they may discriminate between closely or less closely related larvae when rearing new queens or drones. Page & Erickson (1984), Noonan (1986) and Visscher (1986) found a positive discrimination in favour of related brood in queen rearing when workers were given the opportunity to choose from eggs. These biases in favour of close kin were small, varying from 1-2 to 1-6:1 (averaged over many experimental colonies). However, Woyciechowski (1990) could not confirm this in similar experiments. No discrimination has been found where young larvae (in royal jelly) were introduced, not even when the workers were offered a choice between brood of different races (Breed et al. 1984; Visscher 1986). Furthermore, no nepotistic discrimination occurred in cases of emergency queen rearing (Breed et al. 1984; Page & Erickson 1986). Page et al. (1989) claimed to have found nepotism in queen rearing among subfamilies within colonies, but their experimental design and their statistical analysis have been severely criticized by Carlin & Frumhoff (1990) and Oldroyd et al. (1990). Altogether, the evidence for kin discrimination in the rearing of queens is not very strong. As far as we know, there are no reports of nepotistic discrimination of drone larvae. The second way by which individual bees could increase their fitness is by becoming egg layers in the absence of the queen. This can be achieved only by a small percentage of the workers who depend on interactions with other workers in the colony: they have to receive important proteins from 0003 3472/91/110867+04 $03.00/0
other workers and may be attacked (and killed or damaged) by other workers (Sakagami 1954; Velthuis 1985; van der Blom, in press). In colonies with a mixture ofpatrilines, workers should receive more support or experience less competition from full sisters than from less related workers if kin recognition cues play a role. Several papers suggest that this is indeed the case (Evers & Seeley 1986; Frumhoff & Schneider 1987). Thus, for an individual worker, the chances of becoming an egg layer should depend on the composition of the colony. This has hardly ever been investigated directly. Page & Erickson (1988) found indications that drones produced by workers do not originate primarily from the numerically dominant subfamilies. However, they could not tell exactly how many drones had been produced by each of the two subfamilies, and their results may have been influenced by unknown factors linked to the genetic marker (the cordovan locus) they used to distinguish between the patrilines (the bees with the cordovan locus always dominated drone production). The purpose of our experiment was to study the development of egg layers in orphaned colonies in two situations: one where a group of workers finds itself among a large majority of (half-) sisters and the other where workers are surrounded only by a minority of relatives. We used the size of the ovaries as a measure of reproductive potential. If nepotistic discrimination during interactions between adult workers is ultimately important, we predict that workers from the first group would have better developed ovaries than workers from the latter group. To avoid possible artefacts related to introduction of marker phenotypes (Carlin & Frumhoff 1990) and to the use of a very small number of patrilines (Hogendoorn & Velthuis 1988), we used indistinguishable bees of the same race, Apis m. mellifera, and a natural number of patrilines.
9 1991 The Association for the Study of Animal Behaviour 867
868
Animal Behaviour, 42, 5
Queenless colonies of about 2000 workers, without brood, were taken from queenright 'mother colonies' (i.e. colonies with a queen) and installed in six-frame beehives. Half of these mother colonies were bought from a beekeeper living about 100 km away. The bees from the imported colonies were completely unrelated to the ones from our own apiary. Six pairs of unrelated queenless colonies were formed in 1989. The first three pairs were installed on 17 May, the next three pairs on 20 June. Frames of closed brood from each of the queenright 'mother colonies' were placed in an incubator at 33~ Newly eclosed bees were paint-marked according to their origin. A hundred bees of both the colony of origin and of the non-related 'partner colony' were introduced at the same time into each queenless beehive, 2 days after the queenless colonies were installed (19 May and 22 June). Thus, the bees introduced from the colonies of origin found about 2100 relatives among the bees in the hive, whereas the bees introduced from another colony had only about 100 relatives. When a significant number of worker eggs were found in the colonies (2 June and 14 July), the bees were collected and put into a freezer at -20~ The size of the ovaries of all marked individuals that were recovered was determined. For simplicity, we divided the bees into two groups, the bees with small ovaries (Velthuis 1970: stage A-D) and the bees whose ovaries contained developed eggs (E-H). Since age-related factors are very important in the development of laying workers, unmarked workers (of unknown age) could not provide control data on development of the ovaries. We therefore present data only on the workers that were marked. (Since many authors have studied behaviour of paint-marked bees in observation hives and there are no reports that the paint itself influences the bees in interactions, we assume that the paint does not have any influence on our results.) It should be noted that if we find any differences between the development of related or unrelated workers in the hive, we will not be able to conclude that this is completely due to kin recognition. This experiment does not preclude possible forms of inter-colony nest-mate recognition. However, if there are no differences, we can conclude that kin recognition does not seem to influence development of the ovaries. Table I shows the distribution of the workers recovered by the end of the experiment according to
the development of their ovaries. First, we compare the number of recovered workers, without taking into account the development of the ovaries. A Wilcoxon signed-rank test showed that, per experimental hive, there was no systematic difference between the number of recovered workers that were related or unrelated to the majority of the bees in the hive (in Table I comparing 36 with 41, 45 with 47, etc.: Ts=23, N = 12, P>0.05). If we compare the number of workers surviving from one colony of origin that were introduced into colonies with related or unrelated workers (i.e. 36 with 47, 41 with 45, etc.), we do not find any significant difference either (Ts=33.5, N = I 2 , P>0.05). We do not know what happened to the workers that were not recovered. Some may have shifted to other colonies and some will have lost their paint mark. These factors, however, do not seem to depend on the relative degree of relatedness to the bees in the hive, since we found no differences in survival. Three variables may influence the development of ovaries: (l) being related or not to the majority of the bees in the hive; (2) genetically or phenotypically acquired characters related to the origin of the bees; (3) physical conditions in the hive in which the experiment took place. It will never be possible to rule out the second and third factors. It is known that there may be big differences in the reproductive potential between bees of different colonies, based on their genetic and physiological background. By comparing bees from different origins, this cannot be standardized. Furthermore, we know that the situation in the experimental hive (e.g. the amount of food present, the presence of brood, etc.) is of major influence for the actual development of laying workers (this effect was minimized by standardizing the experimental set-up as much as possible). The effects of each of these three variables upon the ovary size were analysed with a logistic regression test (Engelman 1985; Freeman 1987). In this test, the possible (independent) sources of variation were separated to find out which one(s) may explain the observed differences in development of the ovaries ( = the dependent variable). The results are: being related or not to the majority of the bees: ~2=0.877, df= 1, P=0.349; origin of the bees: Z2=16.79, d f = l l , P=0.114; hive in which the experiment took place: ;(2=25.45, df= 11, P = 0-008. This means that the development of the ovaries is influenced primarily by the different situations in the experimental hives and not by the physical or
Short Communications
869
Table I. The development of the ovaries of workers introduced into related or non-related queenless colonies
Total no. recovered Experimental hive
Colony of origin
Related
1 1
1 2
36
2 2
2 1
45
3 3 4 4
3 4 4 3
44
5 5 6 6
5 6 6 5
72
7 7 8 8
7 8 8 7
19
9 9 10 10
9 10 10 9
18
11 11 12 12
11 12 12 11
31
Total
Related Unrelated
Ovaries small
Unrelated
Related
Unrelated
Ovaries large Related
27
41
9
33 42
47 26
10 32
18 30
39
33
20
11
0
0
23
12
20
11 2
18 15
19
2 4
19 22
28
0 9
27 21
34
1 2
27 269
genetic differences connected with the origin o f the bees. These factors were n o t specifically examined. W h e t h e r the introduced bees are strangers or relatives does not have a significant effect o n ovarian development. In o u r experiment we f o u n d n o differences in either the rate of survival, or the n u m b e r of bees t h a t developed into laying workers w h e n comparing the bees that were or were n o t s u r r o u n d e d by a majority of related workers. Therefore, we can conclude t h a t so far there is n o evidence t h a t nepotistic discrimination in interactions of w o r k e r h o n e y bees leads to different chances o f r e p r o d u c i n g in n a t u r a l situations. W e t h a n k H a y o Velthuis, J a n v a n Hooff, K a t j a H o g e n d o o r n and Steven K o l m e s for their suggestions d u r i n g the research a n d their c o m m e n t s o n the m a n u s c r i p t a n d D r J. A. J. F a b e r for helping with the statistical analysis. Miss S. M. M a c N a b
0 6
16
355
9 11
14
351
6 6
8
23
2 8
8
19
23 4
64
20
10
29 6
14
8
3 37
52
Unrelated
7 82
276
79
is t h a n k e d for giving linguistic advice. D r M. Woyciechowski a n d a second ( a n o n y m o u s ) referee gave valuable c o m m e n t s o n the manuscript. The investigations were s u p p o r t e d by the F o u n d a t i o n for Biological Research (BION).
REFERENCES
van der Blom, J. In press. Social regulation of egg-laying by queenless honeybee workers (Apis mellifera L.). Behav. Ecol. Sociobiol. Breed, M. D., Velthuis, H. H. W. & Robinson, G. E. 1984. Do worker honeybees discriminate between unrelated and related larval phenotypes? Ann. entomol. Soc. Am., 77, 737 739. Carlin, N. F. 1989. Discrimination between and within colonies of social insects: two null hypotheses. Neth. J. Zool., 39, 86-100. Carlin, N. F. & Frumhoff, P. C. 1990. Nepotism in the honeybee. Nature, Lond., 346, 70(%707.
870
Animal Behaviour, 42, 5
Engelman, L. 1985. Stepwise-logistic regression. In: BMDP Statistical Software (Ed. by W. J. Dixon), pp. 330-344. University of California Press. Evers, C. A. & Seeley, T. D. 1986. Kin discrimination and aggression in honey bee colonies with laying workers. Anim. Behav., 34, 924-925. Freeman, D. H. 1987. AppliedCategoricalDataAnalaysis. New York: Marcel Dekker. Frumhoff, P. C. & Schneider, S. 1987. The social consequences of honey bee polyandry: the effects of kinship on worker interactions within colonies. Anim. Behav., 35, 255-262. Grafen, A. 1990. Do animals really recognize kin? Anim. Behav., 39, 42 54. Hogendoorn, K. & Velthuis, H. H. W. 1988. Influence of multiple mating on kin recognition by worker honeybees. Naturwissenschaften, 75, 412-413. Noonan, K. C. 1986. Recognition of queen larvae by worker honeybees (Apis mellifera). Ethology, 73, 295-306. Oldroyd, B. P., Rinderer, T. E. & Buco, S. M. 1990. Nepotism in the honeybee. Nature, Lond., 346, 707-708. Page, R. E., Jr & Erickson, E. H. 1984. Selective rearing of queens by worker honeybees: kin or nestmate recognition. Ann. entomol. Soc. Am., 77, 578 580.
Page, R. E., Jr & Erickson, E. H., Jr. 1986. Kin recognition during emergency queen rearing by worker honeybees (Hymenoptera: Apidae). Ann. entomol. Soc. Am. 79, 460-467. Page, R. E., Jr & Erickson, E. H., Jr. 1988. Reproduction by worker honeybees (Apis mellifera L.). Behav. Ecol. Sociobiol., 23, 117-126. Page, R. E., Robinson, G. E. & Fondrk, M. K. 1989. Genetic specialists, kin recognition and nepotism in honeybee colonies. Nature, Lond., 338, 576-579. Sakagami, S. F. 1954. Occurrence of an aggressive behaviour in queenless hives, with considerations on the social organisation of honeybee. Insectes soc., 1, 331 343. Velthuis, H. H. W. 1970. Ovarian development in Apis mellifera worker bees. Ent. exp. appl. 13, 377-394. Velthuis, H. H. W. 1985. The honeybee queen and the social organisation of her colony. Fortschr. Zool., 31, 343-357. Visseher, P. K. 1986. Kinship discrimination in queen rearing by honeybees (Apis mellifera). Behav. Ecol. Soeiobiol., 18, 453-460. Woyciechowski, M. 1990. Do honeybee, Apis mellifera L., workers favour sibling eggs and larvae in queen rearing? Anim. Behav., 39, 1220 1222.