Location: Exotic and Invasive Weeds Research
Title: Prospects for biological control of Cape-ivy with the Cape-ivy fly and the cape-ivy moth Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 14, 2013
Publication Date: N/A
Technical Abstract: Cape-ivy (Delairea odorata, Asteraceae), native to coastal floodplains and mountain riparian zones in eastern South Africa, is an invasive vine in coastal riparian, woodland and scrub habitats in California and southern Oregon. Cape-ivy smothers native vegetation and may impair water flow in coastal riparian areas. The Cape-ivy moth, Digitivalva delaireae (Lepidoptera: Glyphipterigidae), and the Cape-ivy fly, Parafreutreta regalis (Diptera: Tephritidae) have been recommended for field release by the USDA-APHIS-Technical Advisory Group on Biological Control of Weeds (TAG), an international peer panel with members from the U.S., Canada, and Mexico. Applications to release both candidate agents in California and Oregon are currently being reviewed by regulatory agencies. The Cape-ivy fly and Cape-ivy moth were selected for biological control evaluation because they are widespread and damaging in the native South African range. In laboratory efficacy tests, the Cape-ivy fly galled shoot tips, reducing stem growth by 50%, and the Cape-ivy moth killed leaves and entire vining stems, reducing plant growth rate, stem length and shoot and root biomass by 30 to 40%. Among 100 other plant species evaluated in host range choice tests, including 27 native California members of the family Asteraceae that includes Cape-ivy, the Cape-ivy moth fed and reproduced only on Cape-ivy. Similar results were obtained for the Cape-ivy fly in tests across 93 plant species. Both insects complete their life cycle in two months. Once released, the Cape-ivy fly and moth will reduce the ability of Cape-ivy to spread vegetatively and smother other vegetation, and will reduce the long-term survival of Cape-ivy.