Researchers have identified a fungus that only harms fig trees when it partners with another fungus. The finding comes from work conducted at Nagoya University. Against a backdrop of declining fig tree numbers in many regions, scientists have traced disease patterns to a fungal interaction rather than a single culprit. The familiar player is Ceratocystis ficicola, a fungus spread by a tiny beetle known as Euwallacea interjectus. In a twist, Japanese scientists isolated a second fungus, Fusarium kuroshium, which on its own appears harmless to fig trees but becomes dangerous when it grows alongside C. ficicola.
In their experiments, the team exposed fig seedlings to different mixes of fungi collected from the beetle to test which combinations caused damage. A control group received a fungus for comparison. Neocosmospora metavorans, a species found in many plants such as avocados and coffee, was also part of the study. Some seedlings received only one fungus, while another group received a two-fungus mix of F. kuroshium and C. ficicola.
The results aligned with expectations: seedlings exposed to C. ficicola alone wilted. Those given only Neocosmospora metavorans or only Fusarium kuroshium showed little to no harm to the fig trees. Yet the seedlings facing the duo of F. kuroshium and C. ficicola succumbed quickly, drying out within a couple of weeks and developing extensive deadwood areas. This pattern reveals that the two fungi create a harmful partnership that damages fig trees far more than either one does independently.
From these observations, researchers concluded that the combination of F. kuroshium and C. ficicola forms a symbiotic relationship that is detrimental to fig trees. The study underscores how multiple fungal species can interact to drive disease in ways that single organisms cannot achieve alone. The broader implication is clear: managing fig tree health requires attention to the ecological web of microbes associated with beetle vectors rather than focusing on a single pathogen alone.
Other historical discussions note that certain foods may harbor toxic metals; while unrelated to fig fungi, that line of inquiry reflects the long-standing interest in how naturally occurring substances affect living systems. Ongoing research continues to chart the complex interplay between fungi, insects, and plant hosts, with the goal of safeguarding fig populations and maintaining forest and orchard health for the future.