Reingestion of Feces and Excretion Rates of ZN^(65) in Popilius Disjunctus versus Cryptocercus Punctulatus

Oxygen consumption and Zn 6 5 excretion were measured at temperatures of 17°C and 27°C for two similar—sized species of wood—feeding insects, Cryptocercus punctulatus and Popilius disjunctus. In each species, rate of oxygen consumption was approximately doubled, and ZN 6 5 excretion was significantly accelerated at the higher temperature. In animals held at a given temperature, @m1 O 2 consumed/g live body weight was similar. However, radiozinc excretion was much more rapid in P. disjunctus than in C. punctulatus at each temperature. The species differences in Zn 6 5 excretion may reflect the extreme differences in feeding habits of these otherwise ecologically similar inhabitants of decaying logs. Excretion rate of the radionuclide Zn 6 5 seems to be a good index of metabolic activity and may be of promise in the study of trophic relationships.