The polyphagous shot hole borer beetle: Current status of a perfect invader in South Africa

Abstract

The polyphagous shot hole borer (PSHB) beetle is a recent invader in South Africa. Together with its fungal symbiont, Fusarium euwallaceae, it can rapidly kill highly susceptible host plants. Its impact is most profound in urban areas, but it has also been found infesting important forestry, agricultural crop and native species. Since its first detection in 2012, PSHB has spread to all but one province in the country. The beetle–fungus complex has several biological traits that enhance its anthropogenically mediated dispersal, establishment and survival in novel environments – factors that have likely facilitated its rapid spread across the country. We review the history of the PSHB invasion in South Africa, its taxonomic status and the reasons for its rapid spread. We highlight its potential impact and challenges for its management. Finally, we provide an updated distribution map and list of confirmed host plants in South Africa. Of the 130 plant species identified as hosts, 48 of these (19 indigenous and 29 introduced) are reproductive hosts able to maintain breeding PSHB populations. These reproductive hosts may succumb to beetle infestations and act as ‘pest-amplifiers’. The economic impact on urban forests, plantation forestry and agricultural crops may be severe, but the ecological impact of PSHB invasion in native ecosystems should not be underestimated.

Correction to: Symbiotic Fungi Associated With Xyleborine Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) and the Imperative of Global Collaboration

“…The text boxes display important works on beetle and fungal biodiversity for each region. Rooyen et al 2021). In general, ambrosia beetles and their fungi are understudied in Africa.…”

Rapid and cost‐effective detection of Fusarium euwallaceae from woody tissues

“…One reason ascribed to its invasive success is its wide host range. PSHB has been recorded from over 207 tree and woody plant species in the United States and 130 hosts in South Africa (Leathers, 2015; van Rooyen et al, 2021). It can cause the death of healthy, highly susceptible host tree species including important species in agricultural, urban and natural settings.…”

“…For example, over 1000 trees in urbanized Cape Town, South Africa have been earmarked for removal within just 2 years of its initial detection, which will cost the city about ZAR 3 million. A further ZAR 4.5 million would be required to replace these trees (van Rooyen et al, 2021). Impacts on agriculture include costly infestations of avocado orchards in Israel and California (Eskalen et al, 2013; Mendel et al, 2017).…”

“…Impacts on agriculture include costly infestations of avocado orchards in Israel and California (Eskalen et al, 2013; Mendel et al, 2017). Impacts in native systems are currently under investigation in South Africa (van Rooyen et al 2021).…”

“…Therefore, monitoring and host identification procedures often rely on the detection of the F . euwallaceae mutualist in affected trees (e.g., van Rooyen et al, 2021). This is possible as, even though the different Fusarium species that associate with the different Euwallacea species are promiscuous in the native region (Carrillo et al, 2019; Jiang et al, 2021; Lynn et al, 2021), this has not been detected in the invaded ranges (Kasson et al, 2013; O'Donnell et al, 2015).…”