Biological control of the Eucalyptus-defoliating Australian tortoise beetle Trachymela tincticollis (Blackburn) (Chrysomelidae: Chrysomelini: Paropsina) in South Africa by the egg parasitoid Enoggera reticulata Naumann (Hymenoptera: Pteromalidae: Asaphinae)

The Australian tortoise beetle Trachymela tincticollis (Blackburn) was discovered in the Cape Peninsula in 1982. Its ability to defoliate commercially-grown Eucalyptus species posed a threat to this hardwood industry. In 1986, four egg parasitoid species from southwestern Australia, Enoggera reticulata Naumann, Enoggera nassaui (Girault) (Pteromalidae), Procheiloneurus sp. nr. triguttatipennis Girault (Encyrtidae) and Neopolycystus insectifurax Girault (Pteromalidae), were imported into South Africa and released for biological control of this pest. Only E. reticulata became established, achieving a consistently high parasitism rate with a maximum of 96 % over the four-month oviposition period of the host. This was determined by placing laboratory-reared T. tincticollis eggs on Eucalyptus trees in the field. Following its release in February 1986, the effect of E. reticulata on the numbers of eggs, larvae and adults of T. tincticollis were recorded from 1983 to 1991 by various trapping methods. By February 1988, E. reticulata had dispersed throughout the distribution range of its host, and up to 1330 km from the release sites. Behavioural and climatic factors have been invoked to explain why the other three parasitoid species failed to become established.