Author
Lorraine W. Strathie
strathiel@arc.agric.za
Agricultural Research Council, Plant Health and Protection
Hilton
Coauthors
Sakhi MC Sambo, Agricultural Research Council, Plant Health and Protection, Hilton, South Africa
Lavhelesani E Mawela, Agricultural Research Council, Plant Health and Protection, Hilton, South Africa
Daniella Egli, Agricultural Research Council, Plant Health and Protection, Hilton, South Africa
Abstract
The annual herb Parthenium hysterophorus (Asteraceae: Heliantheae) has global notoriety for its detrimental impacts to agricultural production, conservation of biodiversity, and the health of humans and animals. Relatively few affected countries have intentionally implemented biological control measures, although these are known to be effective. In South Africa, the stem-boring weevil Listronotus setosipennis (Curculionidae), the leaf-feeding beetle Calligrapha bicolorata (Chrysomelidae), the seed-feeding weevil Smicronyx lutulentus (Curculionidae) and the summer rust fungus Puccinia xanthii var. parthenii-hysterophorae (Uredinales) were introduced, supplementing the winter rust fungus Puccinia abrupta var. partheniicola (Uredinales) already present. Contrary to predictions of local suitability for C. bicolorata, its establishment has been hindered. By contrast, L. setosipennis, which dispersed slowly, and S. lutulentus, with early measurable impacts, both established readily. The insect agents have been assessed annually at release sites during the past decade. Outcomes are discussed in relation to release factors. While detrimental impacts of P. hysterophorus are still significant, the biocontrol agents have caused localised damage, which continues to expand. Findings may interest other countries utilising or considering these biocontrol agents. Biological control remains an essential method to manage P. hysterophorus.
Keywords
parthenium weed
releases
monitoring
establishment
Highlights
Introduced insect agents have been established on Parthenium hysterophorus in South Africa.
Field establishment and outcomes of the released insect agents have been variable.
Field populations of the two weevil agents have increased.