Host range and impact of the flower-feeding moth, Cochylis campuloclinium – a biological control agent for Campuloclinium macrocephalum, in South Africa

ABSTRACT

Campuloclinium macrocephalum (Less.) DC. (Asteraceae) (pompom weed), an invader in South Africa and Swaziland, threatens biodiversity conservation, agriculture and tourism in the region. We report on the host range and impact of the flower-feeding moth, Cochylis campuloclinium Brown (Lepidoptera: Tortricidae), the second insect biological control agent to be considered for C. macrocephalum in South Africa. Laboratory host-specificity tests were conducted on 31 Asteraceae species. Field host range studies included 17 non-target Asteraceae species. Results of both C. campuloclinium laboratory and field host-range trials indicated that it is suitably host specific. In laboratory host-range trials, only C. macrocephalum and the closely related native, Adenostemma caffrum DC. (Asteraceae), received feeding damage, while in field host-range trials, the moth was only recorded on the target. Laboratory impact studies showed that C. campuloclinium destroyed a significant number of florets in flower buds (76%) and seeds in mature flowers (54%). Based on evidence from the native range, there appears to be no competitive interactions between C. campuloclinium and the already established stem- and leaf-deforming thrips, Liothrips tractabilis Mound & Pereyra (Thysanoptera: Phlaethripinae). The two insect agents should perform a complementary role of reducing flowering (L. tractabilis) and seed production (C. campuloclinium). Based on the above data, permission for the release of the moth was sought in August 2015.

KEYWORDS:

• Asteraceae
• Lepidoptera
• Tortricidae
• host-specificity testing
• weed biological control
• pompom weed

Acknowledgements

We thank E. Richter, S. Sambo, M. Gareeb, D. Nkala, M. Yengwa, L. Khumalo, L. van der Westhuizen and P. Mpedi of the Plant Protection Research Institute (PPRI) for technical assistance. S. Neser, T. Olckers, J. Goodall, L. Henderson and H. Klein (PPRI) are thanked for their various inputs to the programme. J. Briano (USDA SABCL, Argentina) is thanked for contract and research facilitation. We gratefully acknowledge financial support from the Department of Environmental Affairs (DEA) National Resource Management Programmes (NRMP), the KwaZulu-Natal Department of Agriculture, Environment and Rural Development's Invasive Alien Species Programme, and the Agricultural Research Council.

Disclosure statement

No potential conflict of interest was reported by the authors.