Abstract
To throw light upon the complex relations between the rice weevils, Calandra oryzae L. and C. sasakii TAKAHASHI, and among their geographical strains, the author compared some physiological and ecological characteristics of 10 strains of both species which were collected from different districts of the world. The strains used in the experiment are as follows : C. oryzae from Celebes (CB), Portugal (Po), Japan (JL), Siam (SH), and C. sasakii from Nepal (NE), Canada (CA), Australia (AU), Formosa (Fo), Argentine (Rz) and Japan (Js). On each species, differences in body size among strains are associated with those in some other characteristics, as tabulated in the following. The following sort of parallel variation is exhibited by C. sasakii : when the body size is small, the ratio of the adult longevity at high density to low density is large, the ratio of the rate of reproduction at high density to low density is large, and that at 33℃ to 30℃ is large. In C. olyzae these characteristics give reversal of the association with body size in C. sasakii. It is supposed that these strains represent two series of differentiation of respective species. Furthermore, the differentiation in C. sasakii from the larger sized strain to the smaller one seems to be directed towards the adaptation to the life in stored products.[table]
