Ambrosia Beetles Fungi Farmers

If you are an arborist you may be familiar with the term Ambrosia Beetle . Entomologist so named these beetles which eat fungi which they spread to trees/wood on their bodies using special structures called mycangia. Over 3500 species of ambrosia beetles exist and even more bark beetles which can either feed on fungi or tree vascular tissue. This is a great thing those interested in biodiversity, but this combination can have deadly effects on the host tree. Whether its Elm Bark Beetle (Scolytus scolytus) and Dutch Elm Disease (Ophiostoma ulmi) or the Mediterranean Oak borer (Xyleborus monographus) and its vascular wilt causing fungal partner (Raffaelea montetyi) these beetles can have severe tree health and economic impacts when populations explode or non native species are introduced to areas where host trees bear no natural defense.

In California, we are facing the introduction of several Ambrosia Beetles which are causing significant losses in both native and landscape trees. The Polyphagous Shothole Borers (Euwallacea fornicatus and related species) in Southern California appears to be a wide host generalist, attacking several hundred species, and severely impacting more than 100 different tree species. The scope of impact is still unrealized, but prospects don’t look good for many urban and wild landscapes in the state. What this means for any interested Arborist working in impacted areas, a great opportunity for collaboration and creative solutions are warranted to handle this unprecedented epidemic. There has been little experimentation into the biological control options using fungi that can either halt the growth of the fungal symbiont (Fusarium sp.) or the Shothole Borers themselves.