INSECTS, ARACHNIDS AND REPTILES 



carotenoid in immature insects and a mixture of a- and p-carotenes in 

 mature insects. 



Recently Goodwin and Srisukh^^. 3 8 \i2ivt investigated both 

 Schistocerca gregaria and the African Migratory Locust, Locusta 

 migratoria migratoriodes R and F., and have identified the rose-coloured 

 carotenoid as astaxanthin and the yellow pigment as ^-carotene. 

 p-Carotene exists principally in the fatty tissues, haemolymph and 

 gonads, and astaxanthin in the integument only. In mature males 

 some [3-carotene finds its way into the cuticle {see p. 222). 



As the haemolymph of both Locusta and Schistocerca contains only 

 [^-carotene 600 and 3000 [xg. per 100 ml. respectively, but no astaxan- 

 thin, and as there is no astaxanthin in the locusts' food, it can only be 

 assumed that astaxanthin can be synthesized in the integument from 

 3-carotene ; for as previously stated there exists no confirmed case of 

 carotenoid synthesis de novo by animals. 



There is good evidence that in the wings of Schistocerca and Locusta 

 as well as of the red locust {Nomadacris septemfasciata) astaxanthin 

 occurs as a protein complex. ^ ^ 



In some regions of Africa, locusts are an important dietary consti- 

 tuent and as well as other nutrients can provide a fair amount of pro- 

 vitamin A (^-carotene). Goodwin ^^ has arrived at a mean figure of 

 10-15 [Jtg./g. (fresh wt.) for laboratory-reared insects. This value 

 (which is somewhat lower than the values quoted by Brodskis and 

 Rungs) ^ ° can easily be doubled in females containing fully developed 

 eggs. It is appropriate to notice here that Brodskis *i and Brodskis 

 and Rungs * ° claim that vitamin A per se exists in locusts ; Goodwin 

 and Srisukh, ^ ^ however, could not find vitamin A in either Locusta 

 or Schistocerca^ although they had available miich more sensitive 

 apparatus than had Brodskis and Rungs. Two further points which 

 make the absence of vitamin A most probable are {a) its absence from 

 all other insects examined, and {b) the fact that some insects, at least, 

 can exist on diets completely devoid of either carotenoids or vitamin 

 A, "• 1 2 amongst which is the orthopteran Blatella germanica. " 2. ■» » 

 If, however, the similarity between insects and Crustacea in producing 

 astaxanthin can be extended, it is possible that some insects may 

 produce vitamin A, because it has recently been shown to be present 

 in a number of Crustacea. * *. * & 



Chauvin*" has demonstrated the presence of carotenoids in the 

 oenocytes of Schistocerca^ and the orange-red pigment found by 

 Roonwal * ' at the base of the ovarioles is probably [3-carotene. Goodwin 

 and Srisukh^® have shown that [3-carotene is the only carotenoid in 

 the newly-hatched eggs of both Locusta and Schistocerca ; the p-carotene 



219 



