Population Dynamics of the Tea Scale, Fiorinia theae (Homoptera: Diaspididae), with Biology and Life Tables

Abstract

The tea scale, Fiorinia theae Green, is a serious pest of camellias and hollies in the United States and many other parts of the world. In 1976, an attempt was made to introduce its natural enemies from India into Florida. As a consequence, an aphelinid, Aphytis theae (Cameron), was released at several locations in Gainesville. Though flourishing during spring, summer, and fall, it failed to survive the winters of north-central Florida, despite repeated colonizations during 1978 and 1979. Data taken from September 1977 to August 1978 were used to construct a life table and survivorship curve of tea scale. During that period, the population trend index was 0.98, indicating a slight decline in the tea scale population. Analysis of the life table revealed that the most important mortality factor was dispersion loss of crawlers. The second most important factor was action of natural enemies on nymphs. A measure of the degree to which the trend of corresponding points on the K curve and those of the K curves conform is proposed as an objective method of identifying and quantifying key factors.