Bacterial and eukaryotic microbiomes of the emerging lovebug, Plecia longiforceps, in Korea
Background: Lovebugs (*Plecia longiforceps*) are abundant insects in the Seoul Capital Area, yet their associated bacterial and eukaryotic microbiomes remain poorly characterized. This study investigated the microbial communities of lovebugs collected from geographically distinct regions of South Korea.Methods: A total of 68 adult lovebugs (35 males and 33 females) were collected from Seoul, Pocheon, Incheon, and Suwon in June 2026. Whole-body DNA was extracted and subjected to 16S and 18S rRNA gene amplicon sequencing to characterize bacterial and eukaryotic communities, respectively. Bacterial community diversity and composition were compared among locations and between sexes using alpha- and beta-diversity analyses, PERMANOVA, and LEfSe.Results: Bacterial communities were predominantly composed of Rickettsiales, particularly *Rickettsia*, in specimens from Incheon, Pocheon, and Seoul, whereas Suwon specimens showed increased representation of Enterobacterales, with *Serratia* being particularly prominent. Bacterial community composition differed significantly among sampling locations (PERMANOVA, *p* = 0.001), while no significant differences were detected between sexes (PERMANOVA, *p* = 0.593). *Serratia* was strongly enriched in Suwon and showed significant differences in relative abundance compared with Incheon, Pocheon, and Seoul. Eukaryotic profiling additionally detected diverse fungal taxa, predominantly Ascomycota, including *Cladosporium* and *Curvularia*, together with sporadic detection of other eukaryotes.Conclusion: Lovebugs harbored diverse bacterial and eukaryotic communities, with pronounced geographic variation in bacterial community composition and specific taxa such as *Serratia*. These findings provide a baseline characterization of the lovebug-associated microbiome and suggest that geographic factors may contribute to variation in microbial community structure.