# Multi-Condition Cultivation Reveals the Host Plant-Dependent Gut Bacteria Diversity in Tomato Leafminer (Tuta absoluta) Larvae

## TL;DR

This study shows how the gut bacteria of tomato leafminer larvae differ based on whether they feed on tomato or eggplant plants, highlighting the role of host plants in shaping insect gut microbiota.

## Contribution

The study introduces a multi-condition cultivation strategy to reveal host plant-dependent gut bacterial diversity in Tuta absoluta larvae.

## Key findings

- Eggplant-fed larvae had higher gut microbial diversity compared to tomato-fed larvae.
- Enterococcus mundtii was the most abundant gut bacterium across most conditions.
- High-temperature conditions enriched thermotolerant bacteria like Bacillus wiedmannii and Micrococcus luteus.

## Abstract

The tomato leafminer Tuta absoluta is a major global pest of tomato (Solanum lycopersicum) and eggplant (Solanum melongena). Although feeding on different host plants is known to influence its gut microbiota, comprehensive research remains lacking. Hence, we compared the cultivable gut bacteria in tomato- and eggplant-fed T. absoluta larvae to investigate their role in host adaptation. Herein, the microbes were traditionally cultivated on Luria–Bertani broth, nutrient agar, and Brain Heart Infusion media under different temperature conditions, followed by microbial identification based on morphology and 16S rRNA sequences. Distinct gut bacterial community structures were found between the two host-feeding groups, with eggplant-fed larvae exhibiting higher microbial diversity. Host plant species significantly influenced the composition and diversity of the gut bacteria. Enterococcus mundtii exhibited the highest abundance under most conditions, whereas high-temperature conditions enriched thermotolerant strains such as Bacillus wiedmannii and Micrococcus luteus. Altogether, these findings underscore the significance of a multi-condition culture strategy for comprehensive analysis of insect gut microbiota regarding pest adaptability to different plants. Future research needs to focus on functional validation of the isolated bacterial strains to elucidate the underlying “plant–insect–microorganism” interactions to provide novel insights for developing sustainable control strategies.

Tomato leafminer (Tuta absoluta) significantly affects tomato (Solanum lycopersicum) and eggplant (Solanum melongena) crops worldwide, with its feeding patterns being closely associated with its gut microbiota. We aimed to compare the cultivable gut bacteria of T. absoluta larvae fed on tomato and eggplant to investigate their role in host adaptation. Gut bacteria were cultivated on Luria–Bertani broth, nutrient agar, and Brain Heart Infusion media under different temperature conditions, followed by morphology- and 16S rRNA-based identification. Notably, both feeding groups revealed distinct gut bacterial community structures. Tomato-fed larvae harbored bacteria spanning eight species, five genera, four families, and two phyla. In contrast, eggplant-fed larvae exhibited greater microbial diversity, encompassing 15 species, 10 genera, 9 families, and 3 phyla, including unique genera such as Pseudomonas and Pectobacterium, which was attributed to the host plant contribution. Enterococcus mundtii was the most dominant bacterium, and species such as Bacillus wiedmannii and Micrococcus luteus were most thermotolerant. Overall, these findings highlight the importance of multi-condition culture approaches for thoroughly characterizing insect gut microbiota and underscore the role of host plants in pest adaptability by modulating gut microbial communities, providing new insights for developing sustainable control strategies utilizing “plant–insect–microorganism” interactions.