There are too many invasive alien plant species (IAPs) for all of them to be targeted for biological control. Some species are better suited for biological control while others cannot be targeted because of conflicts of interest (Zachariades et al., 2017) - thus necessitating a prioritization process. This prioritization process is often not possible without a thorough understanding of the impacts of the weed as well as the options available for its control. Additionally, it is suggested in the literature that consultation with experts in the field should be a fundamental component of a prioritization process (van Klinken et al., 2016; Zachariades et al., 2017).  It would reduce subjectivity and therefore provide stronger evidence to funders for the need to work on the most appropriate targets.

The development of a prioritization system for highland invasive species, which would rank species according to their suitability as candidate targets for biological control based on both quantitative assessments and expert opinion, should be considered. This would ensure resources are not wasted on species that are unsuitable for biological control as well as prioritizing plants inflicting the most damage.

However, to fairly prioritize a species a thorough understanding of the plant and its associated insects is required, this is not always possible. Pyracantha angustifoliae is one such species where little is known about the species within its native range other than its distribution. Itis one of the most damaging invasive species to mountain grasslands (Van Wilgen et al., 2008; Henderson pers. comm) and a native range survey would greatly contribute to the prioritisation of the species for a biological control programme.

We aim to prioritize the most common high altitude mountain catchment invaders based on their impact (socially, environmentally and economically). As well as the known options for biological control. The species considered for prioritization include: Pyracantha angustifolia, Populus alba, Populus canescens, Salix  fragilis, Salix babylonica, Rosa rubiginosa, Cotoneaster sp. (C. franchetii and C. pannosus), Acer spp. (A. negundo, A. buergerianum), Fraxinus spp. (F. americana, F. angustifolia, F. pennsylvanica/velutina). A more in depth analysis is needed to identify the most threatening plants.

Last Modified: Tue, 17 Jul 2018 11:17:29 SAST