THE CONTROL OF NEZARA-VIRIDULA L WITH INTRODUCED EGG PARASITOIDS IN AUSTRALIA - A REVIEW OF A LANDMARK EXAMPLE OF CLASSICAL BIOLOGICAL-CONTROL

The history of Nezara viridula egg parasitoid introductions into Australia is critically reviewed. Using largely unpublished file material information is presented on the source of parasitoids, specific identification of parasitoids, numbers of parasitoids reared and released, and effects in the field. At least four species of egg parasitoids, in three genera, have been introduced and liberated into Australia since biological control efforts were first begun in 1933. There are records of 11 introductions involving Trissolcus basalis (Wollaston) (Egypt 1933; West Indies 1952-53; South Africa 1980; Brazil 1980; U.S.A. 1979-81), Trissolcus mitsukurii (Ashmead) (Japan 1962), Ooencyrtus submetallicus (Howard) (West Indies 1952-53), and Telenomus chloropus (Thomson) (Japan 1962; Japan via U.S.A. 1980). Doubt is cast on the specific status of introductions from Italy (1956) and Pakistan (1961), which are recorded in the literature as T. basalis. Evidence is presented that there is currently not enough information available to determine the specific classifications of these importations. Three programs in which Australian field populations of Trissolcus were bred and released elsewhere in Australia are also recorded. Post-release evaluation of introduced N. viridula egg parasitoids in Australia is reviewed. It is proposed that there is only circumstantial evidence to support the claim that N. viridula is under 'good' biological control by T. basalis in Australia. Areas of investigation that are of the most significance to current workers in N. viridula biological control are highlighted in the discussion.