# Gut Bacteria Mediate Aggregation Pheromone Release in the Borer Beetle Trigonorhinus sp

## TL;DR

Gut bacteria in a wood-boring beetle are essential for producing pheromones that attract females, suggesting new ways to control the pest.

## Contribution

This study shows specific gut bacteria are required for pheromone production in Trigonorhinus sp., revealing a novel role for symbionts in insect communication.

## Key findings

- Antibiotic treatment reduced pheromone emission by over 85% in male beetles.
- Recolonization with Acinetobacter guillouiae restored pheromone levels to near-normal.
- Females were no longer attracted to males with depleted gut bacteria.

## Abstract

An investigation was conducted on the wood-boring beetle Trigonorhinus sp., a pest of Caragana liouana, to determine the necessity of gut bacteria for male aggregation pheromone release. Using antibiotic depletion, qPCR, GC-MS, and Y-tube olfactometry, it was verified that a marked reduction in gut bacterial load led to more than an 85% decrease in the emission of two key pheromone components (2,6,10,14-tetramethylheptadecane and heptacosane), and females no longer exhibited significant attraction to treated males. Recolonization with a specific gut bacterial isolate, Acinetobacter guillouiae, restored pheromone emission to near-control levels, demonstrating a strain-specific effect. These findings demonstrate a decisive role of specific gut taxa in the beetle’s chemical communication and suggest feasible avenues for symbiont-targeted pest management.

Gut microbial symbionts are increasingly recognized as key modulators of host insect physiology and behavior, yet their role in pheromone-mediated chemical communication remains insufficiently understood. In this study, we investigated the wood-boring beetle Trigonorhinus sp., a pest of Caragana liouana, to determine the necessity of gut bacteria for male aggregation pheromone release. A combination of antibiotic-mediated bacterial depletion, quantitative PCR, gas chromatography-mass spectrometry (GC-MS), and Y-tube olfactometry was employed. Antibiotic treatment resulted in a marked reduction in gut bacterial load and a concomitant decrease of more than 85% in the emission of two key pheromone components, 2,6,10,14-tetramethylheptadecane and heptacosane. Behavioral assays demonstrated that females no longer exhibited significant attraction to treated males. Furthermore, defined recolonization with a single cultured gut isolate, Acinetobacter guillouiae, was sufficient to rescue pheromone emission. This indicates that particular gut taxa, rather than microbial biomass alone, are essential for pheromone biosynthesis. These findings demonstrate a decisive role of gut bacteria in the chemical communication of Trigonorhinus sp. and highlight the potential of symbiont-targeted strategies for pest management.