# Endosymbiont Infections in Korean Insects: Patterns Across Orders and Habitat Types

## TL;DR

This study explores how three endosymbiotic bacteria are distributed in Korean insects, finding patterns influenced by insect order and habitat.

## Contribution

The study provides baseline data on endosymbiont distributions in Korean insects, highlighting patterns shaped by host taxonomy and habitat.

## Key findings

- Single infections of endosymbionts were more common than co-infections in Korean insects.
- Wolbachia was more frequently detected in terrestrial insects compared to aquatic ones.
- Endosymbiont infection patterns varied by insect order, particularly in Coleoptera and Hemiptera.

## Abstract

Endosymbiotic bacteria—microbes that live inside insect cells—play important roles in shaping the biology and evolution of their hosts. In this study, we examined more than 1000 insects from 14 different orders across Korea to explore how three representative endosymbionts (Wolbachia, Rickettsia, and Spiroplasma) are distributed among hosts living in different environments. Single infections predominated, while co-infections were infrequent among the infected insects. Overall associations among symbiont pairs were weak, but varied among insect orders, with significant associations concentrated in Coleoptera and Hemiptera. Infection rates were broadly similar across most host orders, although Spiroplasma displayed detectable order-level differences. In addition, Wolbachia infections were more frequently detected in terrestrial than in aquatic insects. These findings indicate that endosymbiont infection patterns might be shaped by multiple factors operating at different biological scales. This study provides baseline data on endosymbiont distributions in Korean insects, offering additional context for understanding regional variation in these host–microbe associations.

Endosymbiotic bacteria influence the ecology and evolution of insects through complex associations within host cells. To explore how these relationships vary among environments and taxa, we examined 1028 insect specimens from 14 orders across Korea for infections by three representative endosymbionts (Wolbachia, Rickettsia, and Spiroplasma). Overall, 33.8% of specimens were infected, with single infections predominating and co-infections remaining relatively less common. Weak-to-modest but statistically significant associations were detected between several symbiont pairs (Rickettsia–Spiroplasma, Wolbachia–Spiroplasma, and Wolbachia–Rickettsia). Infection rates exhibited no significant variation among host orders except for Spiroplasma, and Wolbachia infections were more frequently detected in terrestrial than in aquatic insects. These results indicate that endosymbiont infection patterns might be shaped by factors operating at multiple biological scales, including host taxonomy and habitat types. As this study relied on polymerase chain reaction detection, infection frequencies should be interpreted as comparative rather than absolute measures. This survey provides baseline data that might help characterize regional patterns of endosymbiont distributions and their variation across taxonomic and ecological contexts.