Population Dynamics of the California Red Scale, Aonidiella aurantii Maskell, and Its Parasitoid, Aphytis melinus (Howard), in Grapefruit Orchards in Turkey

Abstract

The purpose of this study was to define the population dynamics of the California red scale, Aonidiella aurantii Maskell (Heteroptera: Homoptera: Diaspididae), and its parasitoid, Aphytis melinus (Howard) (Hymenoptera: Aphelinidae), released to control the scale in grapefruit orchards in Turkey. Results revealed that A. aurantii exhibited 3 generations in the spring, summer, and autumn each year for 2004 and 2005. The highest population density of second-stage larvae occurred on leaves at densities of 18 and 46 individuals per 4 cm2 with the lowest density occurring on stems at levels of 7 and 8 individuals per cm2 in grapefruit in both years. Parasitoid populations increased in the summer and into autumn. Parasitation rate was increased by releasing A. melinus adults in the orchards. In 2004 and 2005, respectively, the highest parasitization rate occurred on infested leaves with 60.8% and 40.8%, followed by infested fruits at 25% and 54.5%, on infested shoots with 36.4% and 19.3%, and on infested stems with 8.33% and 15.4%. Second-stage and unmated females of red scale were most dense during the spring, summer and autumn each year, thus, appearing to be the best time for release of parasitoids. These results suggest that in releasing A. melinus in grapefruit orchards in Turkey, 50% of the parasitoids should be released in early spring, 25% in summer, and 25% in autumn.