CAROTENOIDS 



content amounts to about 100 fJ-g./egg. Unesterified astaxanthin occurs 

 in locusts' eyes. ^ ^ 



The genetic control of carotenoids metabolism has been noted in a 

 number of insects, e.g., Bombyx mori, Sphodromantis bioculata, and 

 Colias philodice, and Goodwin ^ ' has recently observed what is possibly 

 a manifestation of this in Locusta migratoria. Four very dark blue 

 immature adult female Locusta, progeny of normal gregarious parents, 

 were examined. The body fat of these specimens was completely white 

 and contained no carotenoids, whereas the integument contained a 

 much higher concentration of astaxanthin than normal. This pigment 

 was probably attached to a protein to form a complex which gave the 

 integument its deep blue colour, for the amounts of the other (non- 

 carotenoid) pigments presents were not different from normal. 



0-06 



fi- Carotene 

 concentracion 



Mature 

 adj/cs 



Stage of development 



Fig. 28. — ^The carotenoid distribution in developing locust (from Goodwin, T. W 

 {1949) Biochem. J., 45, 472). 



Goodwin^* has traced the changes which are identical in both 

 gregarious and solitary phases of both species, in carotenoid distribu- 

 tion during the development of the insects. Figure 28, which can be 

 considered typical, indicate how the metabolism of the two carotenoids 

 differs. After the third stage the concentration of astaxanthin begins to 

 decrease until in mature adults it is extremely small. The carotene 

 concentration on the other hand increases as soon as the locust begins 



220 



