Status of introduced parasites of Queensland fruit fly Dacus (Strumeta) Tryoni. 1962–1965

Abstract

The paper records results and conclusions from field samplings made in eastern Australia during March 1962–March 1965 to assess the influence of opiine parasites introduced from Hawaii in 1958–1959 for controlling the Queensland fruit fly (Strumeta tryoni).

Of the introductions, Opius oophilus alone is established on the mainland, where it appeared to use seven dacine and trypetine species as hosts. Its ability to disperse and the frequency of its recovery were enhanced towards the northern end of its distribution. O. oophilus continued to show marked preferences for parasitic activity in certain fruit types such as Averrhoa carambola. Levels of parasitism fluctuated widely between localities and sampling occasions.

O. longicaudatus occurred alone at Lord Howe Island, where it was active at some 16-38% of sampling sites providing infested fruits. Levels of parasitism of the two established host flies were low and no marked fruit preferences were shown.

Indications are that neither imported parasite is materially affecting the incidence either of its hosts or of native parasites.