Host range testing casts doubt on the suitability of Epiblema strenuana as a biological control agent for Parthenium hysterophorus in Africa
Parthenium hysterophorus (Asteraceae: EPPO A2 List) is an annual or short-lived perennial plant species native to Central and South America and one of the most invasive problematic weeds in many regions of the world. In Africa, P. hysterophorus is a major weed of natural and semi-natural areas, arable land, orchard and forests. P. hysterophorus was targeted for biological control in South Africa in 2003, where Puccinia xanthii var. parthenii-hysterophorae (Pucciniaceae), Listronotus setosipennis (Curculionidae), Zygogramma bicolorata (Chrysomelidae) and Smicronyx lutulentus (Curculionidae) have been released against the pest since 2010. Epiblema strenuana (Lepidoptera: Tortricidae) was imported into quarantine in South Africa for evaluation as a potential control agent. The moth is widespread and damaging on P. hysterophorus in Australia and China but was rejected as a control agent for the weed in India due to development on Guizotia abyssinica (Asteraceae: Heliantheae) during laboratory testing. Although G. abyssinica is not cultivated in South Africa, it is in East Africa (G. abyssinica is an important commercial oil crop in some countries in the region) and there are concerns that the species could spread to this region. Under quarantine no-choice testing, E. strenuana only developed on one of five Ethiopian cultivars of G. abyssinica tested, though there was significant larval feeding damage on all cultivars. In multiple-choice testing, none of the Ethiopian cultivars supported development of the lifecycle and larval damage was significantly lower compared to the same cultivars under no-choice tests. In 2012, South African researchers deprioritised E. strenuana as a potential biological control agent at least until its host range and potential impacts were further evaluated through field trials in Australia.
McConnachie AJ (2015) Host range tests cast doubt on the suitability of Epiblema strenuana as a biological control agent for Parthenium hysterophorus in Africa. BioControl 60, 715-723.