Discussion 245 



Nigrelli: Have they no capacity for food storage? 



Maurizio: They have proteins but no sugar. 



Wigglesworth: As I understand it, the queenless worker develops 

 ovaries but the winter bee does not. That would suggest that there 

 is a more subtle difference in addition to the direct nutritional effect. 



Maurizio: The queen substance is there in the overwintering 

 colony. 



Wigglesowrth : So there is a dual effect. 



Hinton : Do the workers develop ovaries whatever time of the year 

 you remove the queen? 



Maurizio: Yes. 



Kershaw: There is evidence in blood-sucking flies that they take 

 blood under hormonal influence, and that there is an antibiting 

 hormone (Lavoipierre, M. M. J. (1958). Nature (Lond.), 182, 1567). 

 This may be a similar phenomenon. 



Maurizio : We will probably ask Dr. Butler to do this experiment 

 with the queen substance. 



Bourliere: Have you made any determination of oxygen consump- 

 tion in winter bees as compared with summer bees? 



Maurizio: That was done by Corkins and Gilbert (Corkins, C. L. 

 and Gilbert, C. S. (1932). Bull. Wyo. agric. Exp. Sta., No. 187, 1). 

 They found that carbon dioxide output at a hive temperature of 

 4° was 52-62 per cent of the output at 16°. 



Sacher: Is the difference between summer bees and the over- 

 wintering bees in the colony determined directly by nutrition and 

 activity, or is there a change in the behaviour of the colony which is 

 caused by the environment and which in turn leads to these differ- 

 ences? 



Maurizio: The winter bees are inactive; there is no brood, they 

 cannot fly and they stay in the colony in a cluster. The only function 

 is to keep warm in the cluster. 



Sacher: Then the fact that it gets cold and they cluster in this 

 fashion and cease their brood rearing is what leads to this change in 

 survival. 



Maurizio: But the bees begin to brood in February in Switzerland. 

 It depends on the climatic conditions. 



Hinton: There must be some indirect effects here because there 

 are many long periods in the winter which are just as warm. 



Maurizio: In Northern Europe bees are unable to forage for 

 four or five months in winter, and the brood-interval is much longer 

 than in England and Central Europe. 



Rockstein: There may, however, very well be a light-dependent 

 factor, such as a diurnal or photoperiod effect. Thirty minutes 



