Invasive Tamarix (Tamaricaceae) in South Africa: current research and the potential for biological control

Abstract

Most species of Tamarix originate in Eurasia and at least five species have become invasive around the world, including South Africa. However, T. usneoides is indigenous to southern Africa, where the potential for biological control of the invasive species is being investigated. Recent research on the invasive species is reviewed here with particular reference to these South African biocontrol efforts. The successful biological control programme against invasive Tamarix in the USA, using several species of ''Tamarisk beetle'', is being used as a guide for the South African research. The South African programme is complicated by firstly, the presence of the indigenous T. usneoides which raises the precision of host-specificity required, and secondly, the introduced and indigenous Tamarix have a high intrinsic value for phytoremediation of mine tailings dams in South Africa. The phylogenetic proximity of these Tamarix species to each other has contributed to this challenge, which has nevertheless been successfully addressed by molecular techniques used to separate the species. In addition, classical morphological techniques have been used to separate the Tamarisk beetles, so that now they can generally be matched to Tamarix tree species. Overall, it is concluded that given the broad knowledge now available on the ecology and identity of both the trees and their biocontrol agents, the prospects for successful biological control of Tamarix in South Africa are good.

Distribution and abundance of invasive Tamarix genotypes in South Africa

“…In South Africa, it is estimated that 8% (10 million ha) of the total land area is invaded by over 180 alien plant species (van Wilgen et al ., ). Tamarix L. (Tamaricaceae) species are among the terrestrial woody plants invading South African riparian zones (Marlin et al ., ). Globally, several species of Tamarix are listed among the 100 worst alien invasive plants (Lowe et al ., ).…”

“…Determining the correct identity of invasive species, assessing their genetic diversity in the introduced range and quantifying the extent of their distribution facilitate decision‐making for management interventions and allow allocation and prioritisation of resources. A potential biological control agent, the leaf beetle Diorhabda carinulata (Desbrochers) native to Eurasia (Tracy & Robbins, ), has been imported from USA, where it is being used to biologically control Tamarix infestations and is currently under quarantine for host‐specificity testing in South Africa at the Wits University Insectary (Marlin et al ., ). This study will help determine sites for future releases of such biocontrol agents.…”

ARF family identification in Tamarix chinensis reveals the salt responsive expression of TcARF6 targeted by miR167

“…Tamarisk plants exist as shrubs or small trees that are naturally distributed in saline soils of Eurasia, the Mediterranean basin and northern and southwestern Africa (Marlin et al, 2017;Sanz Elorza et al, 2010). Tamarix chinensis Lour is one of the most highly salt-tolerant tree species that is well suited for investigating salt-stress-response genes (Liu et al, 2014).…”

The genus Tamarix (Tamaricaceae) from archaeological to contemporary landscape

“…In recent times, T. usneoides has undergone biological control in the United States and South Africa (Marlin & al. 2017).…”