POPULATION DYNAMICS OF THE WHITEBACKED PLANTHOPPER, SOGATELLA FURCIFERA (HEMIPTERA, DELPHACIDAE) WITH SPECIAL REFERENCE TO THE RELATIONSHIP BETWEEN ITS POPULATION GROWTH AND THE GROWTH STAGE OF RICE PLANTS

摘要

A population census was conducted to describe the effects of the growth stage of rice on the population dynamics of S. furcifera, in particular, on immigration, seasonal abundance, population growth rate, and wing-form expression. The number of immigrants was highest on rice plants 17 to 30 days after transplanting (DAT), which suggested that immigrants prefer to settle or remain more on rice plants at the tillering stage (approximately 20-30 DAT). Population growth rate from immigration to the Ist generation decreased with an increase in rice plant age. In contrast, population growth rate from the Ist to 2nd generation was not influenced by rice plant age and was negatively density-dependent. The percentage of macropters (flyers) was positively related to the growth stage of rice when rice was in the vegetative or early part of the reproductive stage, and reached 100% at about 10 days before heading (booting stage). Thereafter, most adult females molted into macropters regardless of population density. The roles of host plant age and crowding effect on the population dynamics of S. furcifera are discussed.