Population biology of the broad-horned flour beetle,Gnathocerus cornutus (F.) II. Crowding effects of larvae on their survival and development

Summary Crowding effects of larvae on survival and development were examined for the broad-horned flour beetle,Gnathocerus cornutus (F.). The larvae matured about 3 weeks after hatching regardless of their densities, but pupation was severely hindered by crowding. There existed an upper limit for the number of the pupae produced and its mechanism was studied by a statistical analysis of the distribution patterns of pupal cells and the experiment in which glass tubes were artificially supplied in addition as pupation site. These studies show thatG. cornutus larvae have a habit to construct cells for pupation and this habit leads to a contest competition for pupation site at high densities. The significance of the contest competition for population regulation was discussed comparing the results onTribolium confusum Jacqueline duVal.