Biological control of cat's claw creeper (Dolichandra unguis-cati; Bignoniaceae): Current status and future prospects

Abstract

Cat's claw creeper (Dolichandra unguis-cati), native to tropical South America, is a major invasive species and a target for biological control in Australia, South Africa and some South Pacific Island countries. Native range surveys in Argentina, Brazil, Paraguay and Venezuela have identified eight insects and four fungal pathogens as potential agents. Five leaf-feeding insects a tortoise beetle Charidotis auroguttata, two tingids Carvalhotingis visenda and C. hollandi, a leaf-tying moth Hypocosmia pyrochroma and a leaf-mining beetle Hedwigiella jureceki, have been tested and all were released in South Africa. Four of these have become established but are not widespread and cause only limited damage. In Australia, only three of these, C. visenda, H. pyrochroma and H. jureceki were released, while C. auroguttata was not approved due to perceived non-target risks. All agents have become widely established, except for H. pyrochroma which is restricted to riparian corridors in southeast Queensland. In South Africa, an accidentally introduced leaf-spot pathogen, Neoramulariopsis unguis-cati, causes necrotic lesions and premature abscission of leaves in cat's claw creeper infestations, resulting in widespread defoliation. Based on its impact and field-host specificity in its native range and in South Africa, the pathogen has been prioritised for evaluation as a potential additional agent in Australia. The current priority is to seek approval for the introduction of this leaf-spot pathogen into Australia. Future research should focus on the gall-inducing rust Uropyxis rickiana and the seed-feeding weevil Apteromechus notatus as prospective agents.