Biological control of cat's claw creeper, Macfadyena unguis-cati (L.) AHGentry (Bignoniaceae), in South Africa

The exotic vine Macfadyena unguis-cati (L.) A.H.Gentry (Bignoniaceae), cat's claw creeper, has become a significant threat to the biodiversity of a variety of sensitive ecosystems in South Africa. Owing to the nature of the infestations, as well as the difficulties and prohibitive costs associated with both mechanical and chemical controls, biological control is considered to be the most practical and sustainable means of successfully managing the weed in South Africa. The biological control programme against M. unguis-cati was initiated in 1996 and resulted in the release of Charidotis auroguttata Boheman (Coleoptera: Chrysomelidae: Cassidinae). Despite repeated releases, initial rates of establishment were low. Where successfully established, populations of the beetle have been slow to build-up, leading to only limited impact on the weed. Prompted by this lack of success, as well as the high potential for further spread of the weed, additional natural enemies were sought. Two lace bugs, Carvalhotingis visenda Drake & Hambleton, and Carvalhotingis hollandi Drake (Hemiptera: Tingidae), a leaf-mining beetle Hylaeogena (Hedwigiella) jureceki Obenberger (Coleoptera: Buprestidae), a leaf-tying moth Hypocosmia pyrochroma Jones (Lepidoptera: Pyralidae) and a seed-feeding weevil Apteromechus notatus (Hustache) (Coleoptera: Curculionidae) were subsequently imported into quarantine in South Africa for host-specificity testing. With the exception of A. notatus, all have been approved for release and are exhibiting promising initial rates of establishment and damage at a number of field localities. Impact studies have shown that cat's claw creeper is susceptible to sustained herbivore pressure.