THE EFFECT OF POPULATION DENSITY DURING NYMPHAL AND ADULT STAGES ON THE FECUNDITY AND OTHER REPRODUCTIVE PERFORMANCES

抄録

Experiments were carried out to assess the effects of nymphal and adult densities on the fecundity and other reproductive performances of the adults. A high nymphal population density adversely affects the fecundity and the duration of the life span of the adults by giving rise to adults of lighter weight. By contrast, the deleterious effects of the population density of the adults were induced directly by the mutual interference among the adults, which resulted in the shortening of the life span and decrease in fecundity. It was revealed that the physiological conditions of the females, e.g. reproductivity, is determined not only by the population density during the nymphal and adult stages, but also by the nature of the parent eggs : whether the eggs were deposited in the early or late period during the ovipositional period. The percentage reductions in the daily ovipositional rate due to five times increase in densities of nymphs and adults were 15 per cent and 43 per cent, respectively. Therefore, the effect of the population density of the adult on the fecundity was greater than that of nymphal density.