First releases of Liothrips tractabilis (Thripidae), a biological control agent for Campuloclinium macrocephalum (Asteraceae) in South Africa

First releases of Liothrips tractabilis (Thripidae), a biological control agent for Campuloclinium macrocephalum (Asteraceae) in South Africa
Andrew McConnachie
Agricultural Research Council - Plant Protection Research Institute

Pompom weed, Campuloclinium macrocephalum (Less.) DC. (Asteraceae), originates from Central and South America and was first detected in South Africa in 1962.  In the 1980s C. macrocephalum started slowly extending its range and in the 1990s and 2000s it entered a dramatic expansion phase. An invader of grasslands, savannas and wetlands, C. macrocephalum reproduces and spreads via numerous wind-dispersed seeds.  Studies have highlighted the significant negative impact the weed has on biodiversity.  A biological control programme was initiated against the weed in 2003.  Two rust fungi and nine insect species have been found to be associated with the plant in its native range.  Of these, two insect species, Liothrips tractabilis Mound & Pereyra (Thysanoptera: Thripidae) and Cochylis campuloclinium Brown (Lepidoptera: Tortricidae), and one pathogen, Puccinia eupatorii Dietel (Uredinales: Pucciniaceae) were rated (based on damage, range and abundance) as having the most potential for successful control of pompom weed.  The stem-deforming thrips, L. tractabilis, was selected as the first insect agent to be developed and was approved by authorities for release in June 2013. The first field releases were made in October 2013 in Pretoria (Rietvlei Nature Reserve). Since then, successful releases have been made more widely at sites in the Gauteng, Mpumalanga, Limpopo  and  North  West  provinces, in  accordance with  a  strategy developed by  the  National Pompom Steering Committee.  Initial signs of establishment look promising; however, the thrips will have to persist through the winter period before full establishment can be confirmed.