Horizontal and Vertical Dispersal of California Red Scale, Aonidiella Aurantii (Mask.), (Homoptera: Diaspididae) in the Field.

Abstract

Field experiments with sticky traps in South Australia demonstrated that crawlers and males of Aonidiella aurantii (Mask.) were carried up to 312 m by the wind from a scale-infested lemon orchard. Generally, the numbers of scales trapped decreased with increasing height from ground level to 2.7 m, but the distribution of trap numbers at ground level or close to the vegetation was not consistent. Trap numbers decreased rapidly with increasing distance from the source to 19.5 m, then more slowly from 19.5 to 312 m. A linear regression of the logarithms of the trap catches against the square root of distance was shown to describe satisfactorily the density-distance relation for crawlers, males and mature females for distances up to 19.5 m. The use of potted lemon trees as traps demonstrated that crawlers carried by the wind are able to establish themselves on a suitable food-plant following dispersal.