The PSHB –  polyphagous shot hole borer, ambrosia beetle (Coleoptera: Curculeonidae: Scolytinae) is a generalist, insect species, considered to be a pest, due its ability to damage trees by acting as a vector carrying pathogenic fungi. Fungal species are inoculated into reproductive and non-reproductive hosts, causing Fusarium dieback. This invasive beetle and its fungal symbiont, Fusarium euwallaceae (within the Fusarium solani species complex (FSSC)), forms a complex that is internationally notorious for the damage it has caused, especially in Israel and in the United States of America. In these countries, this pest threatens not only urban trees, it is also presenting a major threat to the avocado industries.

In a recent study in South Africa, this ambrosia beetle-fungal complex was detected damaging Platanus x acerifolia (London Plane) trees in the KwaZulu-Natal National Botanical Gardens. Subsequent analysis confirmed the insect to be one of the invasive haplotypes of the PSHB. This is of particular concern to the local avocado industry. Current research within the Avocado Research Programme is therefore aimed at identifying Fusarium spp. isolates sampled from avocado trees to determine the extent of the threat to industry, after which the taxonomy of these isolates will be defined.  We are also in the process of determining the threat on various, commonly growth avocado cultivars through the use of multiple pathogenicity trials.

Read more about Ambrosia beetles and Fusarium dieback on our Fact sheet here

ARP Team Members

Michael du Toit: Assessing the potential threat of Fusarium spp. from the Fusarium solani species complex (FSSC) to avocado, in South Africa