Impact of Microbial Symbionts on Fungus‐Farming Termites and Their Derived Ecosystem Functions

Make the environment protect you from disease: elevated CO2 inhibits antagonists of the fungus-farming termite symbiosis

“…In line with this, the absence of increased Pseudoxylaria growth at ambient (compared to elevated) CO 2 concentrations indicates that decreased CO 2 concentration when mound wall integrity is compromised is unlikely to be the signal that triggers rampant growth of Pseudoxylaria (Visser et al, 2011). Other defenses must therefore be more important to suppress this fungus, such as antifungals (Visser et al, 2012;Um et al, 2013;reviewed by Schmidt et al, 2022), termite weeding and grooming of the comb (Katariya et al, 2017;Murphy et al, 2023), or the competitive advantage that Termitomyces obtains through its dense inoculation during comb formation (Badertscher et al, 1983;Leuthold et al, 1989).…”

“…The termites protect Termitomyces through a series of complementary defenses that collectively provide very robust protection. The termites monitor and weed the fungus comb (Katariya et al, 2017), avoid substrates that contain mycopathogens (Bodawatta et al, 2019), remove and bury Pseudoxylaria to generate hypoxia that kills the stowaway (Katariya et al, 2018), and utilize antimicrobial compounds of their own (Lamberty et al, 2001) or symbiont origins (Um et al, 2013;Schmidt et al, 2022;Murphy et al, 2023). Recent work has also identified volatile terpenes within the headspace surrounding the fungus comb that could be antimicrobial (Burkhardt et al, 2019;Kreuzenbeck et al, 2022).…”

“…Recent work has also identified volatile terpenes within the headspace surrounding the fungus comb that could be antimicrobial (Burkhardt et al, 2019;Kreuzenbeck et al, 2022). The comb headspace can play a role in defense as the termites ensure an enclosed, homeostatic comb environment, generated through elaborate ventilation structures that maintain consistent temperature and humidity (Korb, 2003;Murphy et al, 2023).…”

“…The tightly controlled comb environment, together with the high metabolism of the termites and Termitomyces and the processing of large quantities of decaying plant material, leads to high amounts of CO 2 (Darlington et al, 1997;Konate et al, 2003;Murphy et al, 2023). This leads to the accumulation of CO 2 that can be up to 5% in the central part of the mound in Macrotermes carbonarius (Matsumoto, 1978) and ~ 1.2% in the ventilation turrets of Macrotermes bellicosus (Korb and Linsenmair, 1999;Korb and Linsenmair, 2000;Turner, 2001).…”