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.
SIGNIFICANCE :
• We provide an updated host list and distribution map for South Africa of the globally significant tree
pest, the polyphagous shot hole borer (PSHB, Euwallacea fornicatus). The South African PSHB invasion
represents the largest outbreak of this pest in its global invaded range. PSHB was confirmed to infest
130 plant species in urban, agricultural, and native ecosystems in South Africa, including 44 previously
unreported hosts. Impact in South Africa is in its infancy but will likely be substantial to local economies
and ecosystems. Mitigation has proven difficult, but numerous research projects have been initiated
throughout the country.
