THE INFLUENCE OF LARVAL POPULATION DENSITY ON THE WEIGHT AND THE EMERGING PERCENTAGE OF DROSOPHILA MELANOGASTER

抄録

The larval duration, the emerging percentage, and the weight of Drosophila melanogaster, emerged from the "live yeast medium" or A-medium containing few live yeast and those from the "dead yeast medium." or B-medium containing sufficient dead yeast were compared. (1) The larval duration was not elongated so much when the larval density increased. There was no apparent difference in the larval duration between the A- and B-medium. (2) The emerging percentage began to decrease in the A-medium when the larval density exceeded 20 larvae per vial, then it decreased to near 0 per cent at high larval density. In the B-medium, the emerging percentage did not decrease remarkably at high larval density. (3) The weight of flies began to decrease when the density exceeded 10 larvae per vial, then it kept a nearly constant value at densities higher than 30 larvae per vial in the A-medium. In the case of B-medium the weight did not decrease when the density increased. (4) The action of the shortage of food first takes its effects upon the individual level that is the decrease of the fly's weight, then it appears on the population level that is the decrease of the emerging percentage. (5) The total weight of flies was at the maximum at the density of 20 larvae per vial in the A-medium. In the case of B-medium the total weight of flies increased with advancing densities.