The paper describes fruit sampling carried out in eastern Australia during January 1960–March 1962 to assess the status of parasites of the oriental fruit fly (Dacus dorsalis) liberated in Australia during 1956–1959 against the Queensland fruit fly (Strumeta tryoni). Opius oophilus was the only introduced parasite extant on the mainland in 1962, parasitizing up to 78% of the host fly stages in Averrhoa carambola in north Queensland and 0–35% in other fruit types. O. oophilus was well established in north Queensland at five localities near Cairns and two near Innisfail, and less well established at three localities near the Queensland–New South Wales border. It had died out during 1960 from two localities further south in New South Wales in which it had been well established since late 1958. O. oophilus was present on Lord Howe Island from October 1959 to March 1961 but died out subsequently. O. longicaudatus was extant in low numbers on the island in 1962. Under Australian conditions Opius oophilus mated satisfactorily. The parasite was able to utilize as hosts fruit flies of the following species: Strumeta barringtoniae, S. cacuminata, S. humeralis, S. tryoni, and possibly Afrodacus jarvisi and S. kraussi, but preferences could not be measured with available techniques. Although it was reared from a total of 14 types of fruits, O. oophilus displayed marked discrimination between fruits, but the preferences varied with season and locality. The most consistent preference was for Averrhoa carambola in north Queensland. O. oophilus showed no preference for operating in the more highly infested fruits of any of the six fruit types tested. The maximum dispersal recorded of a population of O. oophilus from a liberation site was 5 miles, 46 months after establishment. A review of climatic factors indicated that winter temperatures of 60°F or less were unfavourable to the persistence of O. oophilus. The presence of O. oophilus was not associated with a reduction in the degree of infestation of fruits. It is suggested that this is contributed to in the north, where climatic conditions for the parasites are favourable, ,by the presence of abundant fruits which are infested by Dacinae but not favoured by the parasite.

In 1950, a programme was initiated to utilize against the Queensland fruit fly (Strumeta tryoni) parasites which were introduced during 1948–1950 into Hawaii, where they produced a considerable reduction in the incidence of oriental fruit fly (Dacus dorsalis). The present paper describes the work carried out under this programme up to October 1959. During 1951–1957 the emphasis was on rearing, at Sydney, on Queensland fruit fly, stocks of Opius longicaudatus and O. oophilus from small stocks imported from Hawaii. It was found that O. oophilus, O. vandenboschi, and O. longicaudatus could parasitize Queensland fruit fly in the laboratory, and that O. longicaudatus could parasitize the Solanum fruit fly, Strumeta cacuminata, which occurs widely in the distribution area of the Queensland fruit fly and hence might act as a valuable alternative host for the parasites. Liberations were made at Coffs Harbour and Sydney in New South Wales in 1956–1957 of 21 000 O. longicaudatus and 1 700 O. oophilus, but establishment was apparently not achieved. The programme was changed in 1957 to provide for larger releases over n much wider area. In view of production difficulties at Sydney, a field station was set up in Hawaii to rear parasites, which were shipped to Australia by air, checked in quarantine at Sydney, and despatched to various parts of Australia for liberation. Between March 1958 and October 1959 the following numbers of foreign parasites were liberated: O. oophilus, 229 200; O. vandenboschi, 28 100; O. longicaudatus and closely related species, 198 700; O. incisi, 27 100; Dirhinus giffardii, 2 500; Tetrastichus giffardianus, 2 500; and Syntomosphyrum indicum, 3 200. The liberations in 1958–1959 were made at 25 locations in New South Wales, 59 in Queensland, 12 in Western Australia, and 6 on Lord Howe Island. The liberations were made in the presence of populations of Queensland fruit fly in New South Wales, Queensland, and on Lord Howe Island, and of Mediterranean fruit fly (Ceratitis capitata) in Western Australia. Data from a total of 185 fruit samples taken between January and August 1959 in New South Wales and Queensland indicate that O. oophilus was possibly established in five localities in New South Wales and two in Queensland, and that some field breeding had occurred of O. vandenboschi and O. longicaudatus in New South Wales. There were no recoveries indicating field breeding of the three species in central or north Queensland. The indications of establishment of O. oophilus are tentative because the relevant samples were taken before the parasite populations had been subjected to winter conditions. There were no recoveries of O. incisi, S. indicum, or T. giffardianus.

Six species of parasitic Hymenoptera and I predatory Lepidoptera from South Africa, and 1

The paper describes techniques used in rearing and transporting parasites of the oriental fruit fly (Dacus dorsalis) liberated in Australia against the Queensland fruit fly (Strumeta tryoni) during 1956–1959. The principal species reared were Opius oophilus, O. vandenboschi, and O. longicaudatus at Sydney and Honolulu, and O. incisi at Honolulu only. The laboratory hosts were Strumeta tryoni alt Sydney and Dacus dorsalis at Honolulu. A culture medium consisting of banana tissue and a carrot-yeast mixture was developed in which the immature host stages developed satisfactorily and were readily available for parasitization. During 1958 and 1959, the major periods of liberation, most of the wasps were reared at Honolulu and sent by air to Australia. To prevent introduction of' unwanted insects, all wasps were immobilized with carbon dioxide for checks of identification at both Honolulu and Sydney. The carbon dioxide treatment had some slightly unfavourable effects which were outweighed by the usefulness of the technique. About 83% of the 583 000 opiine wasps shipped survived to be liberated.