Submitted to: African Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/30/2010
Publication Date: 12/30/2010
Citation: Westhuizen, L., Neser, S., Balciunas, J.K. 2010. Biology and host specificity of Diota rostra. African Entomology. 18(2):246-252. Interpretive Summary: Invasive weeds degrade natural areas, cause billions dollars worth of losses in agriculture, and weed control accounts for more than half the pesticides used in the United States. Classical biological control – the release of carefully selected and tested insects and other natural enemies from the native home of the weed – is a proven strategy for reducing the impacts of invasive weeds, and reducing the use of herbicides. To avoid direct impacts on crops and beneficial native plants, prior to release, the intended agents are screened to assure that they are host-specific, and will not damage non-targets. This paper presents the results of our tests to determine if a moth being considered for use as biological control agent for Cape-ivy is safe enough for release in California, where this vine is a very serious weed. Our tests demonstrate that this moth was not host specific to Cape-ivy, and is, therefore, not safe for release
Technical Abstract: Delairea odorata Lemaire (Cape-ivy) has become naturalised and invasive in many countries including the United States of America where biological control is being considered as a low-cost, long-term solution to managing this invasive vine. Extensive surveys throughout the natural range of the plant in South Africa revealed a large arthropod fauna associated with the plant. Amongst the herbivorous insects showing potential as possible biological control candidates was Diota rostrata (Wallengren) (Arctiidae: Arctiinae), a widespread defoliating moth. In order to assess the potential of the moth as a biological control agent, host specificity and biological studies were conducted in the laboratory. Both larval survival and oviposition preference tests showed that D. rostrata was not restricted to D. odorata. This was also confirmed by field observations. Although D. rostrata is highly fecund and has a short life cycle, it has a wide host range, and this is likely to include other Senecio spp. with soft or fleshy leaves in its new environment. It is therefore not recommended to release D. rostrata against D. odorata in California, USA.