Mass culture of California red scale and its golden chalcid parasites

Abstract

The golden chalcid, Aphytis chrysomphali (Mercet), has been parasitizing the California red scale, Aonidiella aurantii Mask., for more than fifty years in California citrus orchards. Planned use of this parasite, although seriously studied In 1942 and again in 1946, was not actually possible on a large scale until the completion of a culture method in the spring of 1950 at the Riverside Insectary of the Division of Biological Control. This method made possible the production in commercial quantities of the California golden chalcid as well as a species, Aphytis sp. “A,” brought from China in 1947. During this study it was found that the Aphytis female has two addictions that may militate against its general use in the control of red scale. Under certain conditions this parasite temporarily immunizes its host to its attack, and it may destroy the pupae of its own species as well as those of other red scale parasites. The use of inundative releases of the parasite for pest control depends largely on the populations released, not on their progeny. This type of control is similar to spraying and dusting in that a greater amount of lethal material is used than is actually effective, that repetition may be necessary, and that the effect is more or less immediate.