FREE AMINO ACIDS IN INSECTS 127 
The essential amino acids 
Nearly all information on the essential amino acids in insects came from studies on 
insects reared on chemically defined medium. The ten amino acids (arginine, histidine, 
lysine, tryptophane, phenylalanine, methionine, threonine, leucine, isoleucine, valine), 
which were shown to be necessary for growth of the rat!®8, 1%, have been proved to 
be essential also for Tribolium confusum}®, 73,7, Chilo simplex, Apis mellifica®, 
Trogoderma granarium™?, Calliphora erythrocephala® and Pseudosarcophaga affinis! 
(see Table IT). 
TABE ET 
ESSENTIAL AMINO ACIDS OF INSECTS 
(For references see text) 







3S Ss = S 2 5 = = 
Amino acids = 8 & 3 aS aS 2 = € 0 8 : 
ws = & & & 5 = : Qs S = 
Arginine + aL a aL ae ait alls sie at ts 
Histidine + a au ie aM ae aie ate zit he 
Isoleucine + le ae ae alls aE zit si iis ie 
Leucine af alg + “i + =e = af = 4 
Lysine cen Gea ay Ait ec eae ae Arsen OAR ter 
Methionine ae alt. aL ale aie ay ait a6 
Phenylalanine + ak alle ait a ae aie sri Be 
Threonine ait ae aie he ue sie aid 4. a 
Tryptophane st at + AP + 45 +F ate m 4p 
Valine = 4 4F si 4 + a + #F 
Alanine afte 
Cystine ae (25) ae 
Glycine 4. 4 
Proline a * 
Serine 4% 

* Proline and serine appear to be essential only for Blatella males®®. 
RUDKIN AND ScHuLtTz!*® stated, in an abstract form, that Drosophila needs the 
same ten essential amino acids for development as higher animals. In an elaborated 
study on the amino acid requirements of this insect Htnton, NOYES AND ELtis% 
pointed out that arginine, isoleucine and glycine are of primary importance. Glycine 
has especially a growth-promoting effect on Drosophila larvae. According to LAFON'™™” 
cystine plays a particular role in metamorphosis. 
Ten amino acids also have been determined to be essential for the blowfly Phormia 
regina, but, instead of methionine, proline appears to be indispensable? °°. However, 
methionine has a strong growth-stimulating effect. 
For the cockroach Blatella germanica it seems that fewer amino acids are necessary 
House! reported that only valine, tryptophane, arginine, histidine and most probably 
cystine were essential. Similarly HILCHEY®*, who worked on the same species, observed 
References p. 132/135 
