b. Absence of foliclel formation and yolk supply in the о varioles, or even 

 ovisorption in case incomplete ova were already present (de Wilde c. s., 

 1959). 



c. A low level of metabolism (Table 1). 



d. Small size of the corpora allata (de Wilde & Stegwee, 1958). 



Oxygen consumption by adult female Leptinotarsa. All measurements were made 

 on single insects, 33 days after their emergence from the soil (after de Wilde & Steg- 

 wee, 1958). 



. 10 h. photop 



allatectomy (oo) 

 •20 h. photop. 



Effects of allatectomy and re-implantation of corpora allata 



In these experiments, use was made of "long day" beetles only. Allatectomy 

 was performed at the day folloлving emergence, using the "neck membrane" 

 technique. 



To this effect the head was bent downwards by means of a clamp of special 

 design. As a rule both the cc. allata and cc. cardiaca were removed, but the 

 effect was chequed by re- 

 implanting cc. allata only. 26 



a. Effect on behaviour. 



In both male and fe- 

 male beetles, the effect 

 of allatectomy on beha- 

 viour is strikingly similar 

 to that of "short day", 

 as is demonstrated in 

 fig. 1. The change from 

 feeding into burrowing 

 responses merely occurs 

 wdth a somewhat greater 

 delay. 



Reimplantation of ac- 

 tive corpora allata, which 

 was performed in 25 fe- 

 male beetles, of which 18 

 survived for 4 weeks or 



allatectomy (?9) 

 20 h. photop 



2 6 10 U 18 22 



days after emergence 



Fig. 1. Behavioiu" of beetles subjected to a 10 h. photo- 

 period as compared with the effect of allatectomy on 

 betlees grown up mider a 18 h. photoperiod. Each curve 

 shows the number of beetles above soil. The decreasing 

 number is only due to diapause as only surviving beetles 

 are included. 



227 



