Density-related mortality of the flour beetle,Tribolium confusum duval

Life tables were constructed to assess the relative importance of some factors causing mortality of Tribolium confusum and to gauge their response to increasing population density. Observations focussed on three population densities (100, 400 and 800 individual/8 g medium) from the egg to the adult stage. The medium was not renewed in order to maximize predatory interactions. Generation mortality at densities 100, 400 and 800 was 42%, 50% and 74% respectively, i. e. density-dependent. Mortality in the first 10 days was also density-dependent reaching a maximum of 27% at density 800: predation by small larvae on eggs seemed the principal causative factor. The overall pattern of larval mortality was density-independent. Data on the mortality of pupae and callows were ultimately consistent with an inversely density-dependent pattern. Apparently, only mortality occurring within the first 10 days was capable of population regulation.