Invasive Asian Fusarium – Euwallacea ambrosia beetle mutualists pose a serious threat to forests, urban landscapes and the avocado industry

Several species of the ambrosia beetle Euwallacea (Coleoptera: Curculionidae: Scolytinae) cultivate Ambrosia Fusarium Clade (AFC) species in their galleries as a source of food. Like all other scolytine beetles in the tribe Xyleborini, Euwallacea are thought to be obligate mutualists with their fungal symbionts. Published diversification-time estimates suggest that the Euwallacea – Fusarium symbiosis evolved once approximately 21 million years ago. Female Euwallacea possess paired oral mycangia within which foundresses transport their Fusarium symbiont vertically from their natal gallery to new woody hosts. During the past two decades, exotic Asian Euwallacea – Fusarium mutualists have been introduced into the United States, Israel and Australia. Because these invasive pests attack and can reproduce on living woody hosts, they pose a serious threat to native forests, urban landscapes and the avocado industry.