ENDOCRINE EFFECTS IN PHASE DEVELOPMENT IN LOCUSTS 



Эндокринные влияния при развитии фаз саранчи 



G. В. STAAL 



(Laboratory of Entomology, Agricultural University, 

 W'^ageningen , Netherlands ) 



Some locust species зЬолу a highly pronounced phase polymorphism in the 

 field as луе11 as under laboratory conditions. Some phase characters, especially 

 concerning the pigmentation, may be produced fairly well under laboratory 

 conditions; biométrie extremes on the other hand are difficult to realize 

 in the laboratory (Gunn & Hunter Jones, 1952). 



The full range of pigmentation types in the larvae and adults of Locusts may 

 be obtained easily by varying several factors, such as rearing density, R. H. 

 and background colour, according to this scheme: 



The mode of action of these external stimuli ultimately leading to the dras- 

 tic phase changes which may occur during larval development, is only poorly 

 known. 



Weed Pfeiffer (1945) obtained a change in the blood colour from pale 

 into green following extra implantation of corpora allata in the grasshopper 

 Melano'plus. 



Joly P. & Joly L. (1953) obtained the same effect more, pronounced 

 in Locusfa. They observed a complete shift from the orange black gregarious 

 pattern to a green solitary colour type fohowing implantation of С A. in larvae, 

 not depending upon the external conditions which normally are responsible 

 for such changes. So the effect of surplus C. A. hormone is able to override 

 the gregarious high density stimulus completely, at least as far as pigmentation 

 is concerned. 



This is remarkable while under normal conditions the gregarious stimulus 

 overrides the other colour types. It may be supposed that either the production 

 of C. A. hormone in gregarious larvae is less than in solitary larvae, or that the 



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