Bionomics of California Red Scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae), on Orange Fruits, Leaves, and Wood in California's San Joaquin Valley

Abstract

Development and reproduction of California red scale (CRS)were monitored on navel orange trees in a grove in California's San Joaquin Valley between 1976 and 1978. Three generations were completed each year with a possible fourth on fruits. The number of crawlers settling in each succeeding generation in a given year increased on fruit, decreased on wood, and remained comparatively stable on leaves. Fruits were the most advantageous settling site, followed by leaves or green twigs, and wood the poorest. In general, CRS on the more favorable substrates had comparatively faster maturation, higher percentage of juvenile survivorship, and greater reproductive rates. Reproductive life span was little influenced by substrate. Sex ratios favored males on leaf tops, females on fruits, and usually females on wood. A large proportion of juvenile CRS died during cold winters, but hot summer temperatures had little apparent effect on survival. The parasitoid Comperiella bifasciata Howard completed three or four generations annually with highest percentage of parasitism in CRS on fruits and lowest in CRS on wood.