312 



THE BIOCHEMISTRY OF B VITAMINS 



mental animals are kept, the larvae are reared in a 30° C incubator on 

 a whole wheat stock diet. Ten day-old larvae are then placed upon appro- 

 priate experimental diets, and growth measured by weekly weighing. In 

 this manner, the experimental results obtained accord beautifully with 

 those obtained in nutritional research with higher animals. 



Table 17. Quantitative B Vitamin Requirements of Several Insect Species 

 (ng/unit of diet) 



Species 

 Aedes aegypti 



Drosophila melanogaster 



Galleria mellonella 



Tribolium confusum 



Blatella germanica 



0.4 



xg/ml 



4.0 



Mg/gm 



1.0 



Mg/ml 

 0.05-0.10 



Mg/gm 



Folic 

 acid 



0.2 



Mg/gm 



Biotin 



0.05 



Mg/ml 



0.10 



Mg/gm 



2000.-4000. 



Mg/gm 



Qualitatively, the B vitamin requirements of insects appear to resemble 

 closely those of the vertebrates. A summary of much of the existing data 

 in this regard is given in Table 16. The limited amount of quantitative 

 data as yet available is insufficient to make valid comparisons, but is 

 summarized in Table 17. Consideration of these data in terms of their 

 relationship to insect vitamin composition 34, 35 shows that, as in higher 



* Growth Rate: Reciprocal of the period in days in which 50% of the insects were completely developed, 

 expressed as the percentage of the period required by a yeast fed control group. 



t Number surviving: The number of the original group of twenty insects that completed development. 

 % Index: Product of the growth rate and number surviving. 



animals, there is a rough correlation between the amounts of the various 

 vitamins required and the amounts found in the animal. The nicety of 

 response obtained in determining requirements is indicated by Figure 2, 

 which shows the growth of cockroach nymphs on various levels of 



