Rotarides Mihály (szerk.): A Magyar Természettudományi Múzeum évkönyve 33. (Budapest 1940)

Tóth, L.: The protein metabolism of the Aphids

THE PROTEIN METABOLISM OF THE APHIDS. By L. TÓTH (Budapest). It is known long ago, that Aphids, soaking vegetable liquids, are great wasters of food, and that their excrement contains large quantities of carbohydrate, so that this becomes a favourite nourishment of ants. This extensive waste of carbohydrate is explained by BüSGEN and, lately, by RAVVITSCHER, in the following way. The food of the Aphids contains very much carbohydrate but only a small quantity of protein. This disproportion is equalized by the animal by taking very much food, most carefully retaining and digesting the protein, while discharging the carbohydrate surplus in its excrement. Thus, the animal so to say densities its protein-nourishment. This witty explanation seems to be so evident, that the scientific literature accepted it, without having exact proofs as support. It can only be accepted, however, if the fact is proved, that the excrement contains essentially smaller protein percentage, as the nourishment, taken up. The literary informations are, in this respect, very scanty: RAUNER (1894) states, that the dried excretum of the Aphids contains 3.5 % protein and 93 % carbohydrate. On the other side, 90 % of the nourishment of the Aphids, the liquids or juices of the sieve tubes consist, according to KOSTYTSCHEW (1931), different sugars, while the protein contents are vanishingly little, so, that even in the Gourd family — where it is of an exceptionally high figure — it is only 5 %. Protein Carbohydrate Excrement RAUNER (1894) 3.5 % 93 % Nourishment KOSTYTSCHEW (1931) 1—2—(5) % 90 % Comparing these data with each other, it becomes evident, that the protein contents of the nourishment of Aphids is not greater than that of their excrement: that is to say, one cannot speak of a densifying of the protein food. Now the next question is: how great is the protein need of the animal? Unfortunately we have not even approximate data in this respect. In order to receive some approximate result, I have undertaken examinations and measurements regarding metabolism fol-