Abstract
To elucidate the metabolic fate of nutrients ingested at different larval ages, several radioactive compounds were injected into female larvae from the 4th instar to larval maturation and radioactivity incorporated into cocoon shells and matured eggs was determined. As for cocoon shells, 14C-glycine and 14C-glucose were markedly incorporated when injected during the last half of the 5th instar. The incorporation of 14C-leucine, 14C-tyrosine, 3H-uridine and β-14C-sitosterol remained at a low level throughout feeding periods. While these isotopes were incorporated into the matured eggs at different degrees depending upon the larval development. The changing profiles in incorporation were roughly grouped into the following two types; (1) a relatively high incorporation at the early phase of the 5th instar, which was observed in the case of 14C-glucose, 14C-glycine, 14C-leucine and 14C-tyrosine, (2) a continuous increase in incorporation of 35S-methionine, 3H-uridine and β-14C-sitosterol according to larval growth.
