Does cryptic microbiota mitigate pine resistance to an invasive beetle-fungus complex? Implications for invasion...

Area of Science:

• Ecology
• Evolutionary Biology
• Forest Science

Background:

• Microbial symbionts aid invasive pests in colonizing new environments.
• Mechanisms by which symbiotic invasions overcome native plant resistance are poorly understood.

Purpose of the Study:

• To investigate how the invasive red turpentine beetle (RTB) and its associated fungi overcome native plant defenses in China.
• To elucidate the role of microbial symbionts in mitigating plant resistance.

Main Methods:

• Investigated the interaction between the invasive RTB, its fungal symbionts (Leptographium procerum), and native Pinus tabuliformis.
• Analyzed the role of newly acquired Chinese-resident fungi in the RTB complex.
• Quantified levels of phenolic defensive chemicals (naringenin) and soluble carbohydrates (pinitol) in infected pines.
• Assessed the biodegradation of naringenin by cryptic microbiotas within RTB galleries.

Main Results:

• Newly acquired Chinese fungi by RTB induce high levels of naringenin, a pine defensive chemical.
• Elevated naringenin levels normally suppress the invasive beetle-fungus complex.
• Cryptic microbiotas within RTB galleries degrade naringenin, facilitating invasion.
• Pinitol, a soluble carbohydrate in P. tabuliformis, is retained in infected phloem and aids naringenin biodegradation by microbiotas.

Conclusions:

• Cryptic microbiota associated with invasive symbiotic complexes can mitigate native host plant phenolic resistance.
• This microbial mitigation provides a potential mechanism for overcoming biotic resistance to symbiotic invasions.
• Understanding these interactions is crucial for managing invasive forest pests.