Cape ivy (Delairea odorata) is a scrambling, semi-succulent vine native to southern Africa that has become a significant environmental weed of moist forests across Victoria, South Australia, New South Wales and Tasmania. It was introduced into Australia as a cultivated ornamental garden plant in the temperate region, and is still commonly found growing in suburban gardens. There is strong evidence from other invaded locations (e.g. west coast of USA) that Cape ivy invasion reduces native vegetation biodiversity and alters forest structure by damaging branches of native shrubs and trees.
Our research aims to develop a biological control (biocontrol) solution for sustainable Cape ivy management across Australian forests, with a focus on two candidate insect agents: a gall-forming fly (Parafreutreta regalis) and a stem-boring moth (Digitivalva delaireae). We will conduct a range of host-specificity tests with at least one of these insects. These tests will concentrate on non-target plant species closely related to Cape ivy, including Australian native plants, to evaluate risks the candidate agent could pose if introduced into Australia.
This research on Cape ivy is part of a broader project seeking biological solutions for the sustainable management of environmental weeds of temperate forests, including wandering trad (Tradescantia fluminensis) and angled onion (Allium triquetrum), co-funded by CSIRO and the Commonwealth Department of Industry, Innovation and Science and supported by the Community Weeds Alliance of the Dandenongs.