Strategies for the biological control of invasive willows (Salix spp.) in Australia

Abstract

Willows (Salix spp.) are Weeds of National Significance in Australia where a large number of taxa are naturalised in temperate regions and can cause serious environmental degradation of riparian and wetland habitats. Several species are of economic or ornamental value and conflicts of interest could arise with planning their suppression. Biological control of six willow species (S. alba L., S. cinerea L., S. fragilis L., S. nigra Marshall, S. viminalis L., S. x rubens Schrank) is under consideration in Australia using three approaches based on targeting different morphological structures. A rich phytophagous biota associated with Salix in their regions of origin indicate a range of organisms are available for development as biological control agents. Implementation strategies will depend on the host species targeted for biological control, their reproductive strategies, the level of control required to reduce environmental impacts and the level of conflict of interest associated with a biological control program.

Wide spread invasion without sexual reproduction? A case study on European willows in Patagonia, Argentina

“…In consideration of the severe ecological damages that willows of the species complex cause in Australia (Adair et al 2006) a similar scenario seems to be probable in Argentina. Accordingly, investigations especially concerning the effect of invasive willows on native species by competition and introgression are highly recommendable.…”

“…Being native to Europe and parts of Asia, these dioecious species have been introduced to several regions including Australia, New Zealand, South Africa and North and South America where they have become naturalized along river margins (Glova and Sagar 1994;Shafroth et al 1994;Urban and Eardley 1995;Correa 1998;Greenwood et al 2004). In Australia S. alba, S. fragilis and S. 9 rubens are considered to be weeds of national significance due to their widespread distribution and the substantial ecological damage that they cause (Adair et al 2006). In Patagonia, the riparian landscape is dominated by several taxa of the Salicaceae, mainly willows introduced from Europe (Naumann 1996).…”

Are Vegetative Reproduction Capacities the Cause of Widespread Invasion of Eurasian Salicaceae in Patagonian River Landscapes?

“…In Australia, some invasive Salix species were declared as ‘weeds of national significance’ with e.g. S. cinerea, S. babylonica and S. fragilis spreading aggressively [11], [8], [12]. Salicaceae are known to alter fluvial dynamics and to facilitate the development and growth of sand bars and islands [13] and thus have traits that could alter the ecosystem profoundly if they are invasive.…”

Invasive Spiraea tomentosa: a new host for monophagous Earias clorana?

“…Recently, Australia proposed a biological control of alien species of willows (including Salix viminalis; Adair et al 2006), which are major invaders of riparian zones in Australia (Greenwood et al 2004). The list of insects (mainly specialists restricted to Salix species) that could potentially be used as biological control agents includes E. clorana.…”