THE B VITAMIN REQUIREMENTS OF ANIMALS AND PLANTS 311 



To an extent exceeding that in the vertebrates, insect B vitamin re- 

 quirements vary with the phases of the animal's life. Larval requirements 

 are much higher (and B vitamin content apparently lower) than in the 

 adult, and the requirements for successful pupation, exuviation, and 

 reproduction may be even more extreme. Thus Aedes aegypti larvae from 

 bacteriologically sterile eggs complete metamorphosis on a sterile diet 



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AGE OF NYMPHS (DAYS) 



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Figure 2. Growth of cockroach nymphs on various levels of choline. 



only when it contains adequate amounts of biotin, 18 and the creation of 

 abnormally high B vitamin levels in serum causes premature shedding 

 of the old skin of Tristoma infestans larvae. 19 The high level of panto- 

 thenic acid in the royal jelly of the bee is also suggestive in this regard. 20 

 While a relatively large number of insects has been studied, the number 

 is actually small in view of the great variety of known species. This 

 variety provides the broadest possible latitude for experimental work, as 

 previously stated, and with relatively few difficulties. Illustrative of this 

 fact are the studies of Sarma et al. with the rice moth larva (Corey ra 

 cephalonica St.), which have demonstrated in a variety of ways to be 

 discussed later the similarity that exists between vertebrate and arthropod 

 vitamin metabolism. In a manner similar to that in which higher experi- 



