HORMONES, SELECTIVE FEEDING AND REPRODUCTION 

 IN CALLIPHORA 



Гормоны, избирательное ли гапие н размножение у каллпфоры 



J. STRANGWAYS-DIXON 



(Department of Zoology, Cambridge, England) 



It is ПОЛУ generally accepted that the median neurosecretory cells (m. n. c.) 

 and the corpus allatum (c. a.) influence insect reproduction. After removal 

 of the с a., eggs will develop up to the yolk deposition stage but no further 

 (Wigglesworth, 1936, Pfeiffer, 1939, E. Thomsen, 1942), but removal 

 of the m. n. с prevents eggs from reaching even this stage (E. Thomsen, 1948, 

 1952). 



The purpose of the investigations to be described was to discover to what 

 extent and in Avhat way diet might influence and be influenced by reproduction. 



When isolated females are alloAved to select from protein*) or carbohydrate 

 solutions contained in identical capillary tubes, protein is ingested in large 

 quantities during the phase preceding yolk formation, but decreases during 

 yolk formation. Carbohydrate ingestion, on the other hand, is low initially 

 but increases during yolk formation. At yolk formation the cycle begins again. 



FUes ingesting carbohydrate but no protein are unable toreproduce (Fraen- 

 kel, 1940). The carbohydrate consumption of these "sugar flies" remains 

 at a constantly 1олу level equivalent to that shown by reproducing females 

 during the pre-yolk phase. 



Castration has no effect upon the first selective feeding сз^с1е, but, presum- 

 ably because the ingested food is not utilised for yolk formation, the cycle 

 is not repeated. Carbohydrate consumption remains high and protein ingest- 

 ion low. 



Extirpation of the c. a. from either normal or ovariectomised females 

 results in carbohydrate ingestion remaining low. Protein is ingested normally. 



The с a. therefore appears to be responsible for carbohydrate ingestion 

 cycles. This theory is enhanced by the fact that the с a. fluctuates cyclically 

 in reproducing females, is constantly large in ovariectomised females and is 

 constantly small in sugar fHes. 



E. Thomsen (1940) was the first to show that the с a. of ovariectomised 

 females became hypertrophied. She suggested that this might indicate a 

 reciprocal influence of the ovaries upon the с a. Scharrer (1948) suggested 



*) The term protein, for convenience, is used throughout this papc^r as a shortened form of 

 ,,])rotein-containing mixture consisting of Marmite (an extract of yeast) dissolved in milk." 



137 



