oa African Entomology - Ecology, distribution and natural enemies of the Eucalyptus-defoliating tortoise beetle Trachymela tincticollis (Blackburn) (Chrysomelidae: Chrysomelini: Paropsina) in southwestern Australia, with reference to its biological control in South Africa
The Eucalyptus-defoliating tortoise beetle Trachymela tincticollis (Blackburn) was detected in Cape Town in 1982 and was considered a threat to the South African hardwood industry. Studies in southwestern Australia on potential biological control agents culminated in the release of four parasitoid species in South Africa. Only one species, Enoggera reticulate Naumann (Hymenoptera: Pteromalidae: Asaphinae), became established, but achieved a 96 % parasitism rate. In this paper, data on the ecology, distribution and associated natural enemy complex of T. tincticollis in southwestern Australia are discussed, relative to the success of the biological control programme. The natural distribution of T. tincticollis coincided with that of its host, Eucalyptus gomphocephala DC and was centred within Ludlow Tuart Forest, where these studies were concentrated. Four species of Tachinidae (Diptera) parasitized T. tincticollis larvae and one mite species preyed on its eggs, but the most promising biological control agents were four egg parasitoid species. Two species, E. reticulata and Procheiloneurus sp. nr. triguttatipennis Girault (Hymenoptera: Encyrtidae), were specific to T. tincticollis eggs, and two, Enoggera nassaui (Girault) (Hymenoptera: Pteromalidae) and Neopolycystus insectifurax Girault (Pteromalidae), occasionally emerged from parasitized eggs. Four hyperparasite species, Signiphora sp. Ashmead (Hymenoptera: Signiphoridae), Neblatticida sp. nr. lotae (Girault) (Encyrtidae), Baeoanusia albifunicle Girault (Encyrtidae) and Aphanomerella ovi Dodd (Platygasteridae), were associated with the first three primary parasite species. Enoggera reticulata parasitized 42 % of T. tincticollis egg batches placed in the field, of which 27 % were hyperparasitized by Neblatticida sp. The flowering of the Western Australian peppermint tree, Agonis flexuosa (Sprengel) Schauer, that forms the understorey in Ludlow Tuart Forest, coincided with the phenology of T. tincticollis larvae and could be used as a biological indicator of the insect's ecology.
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