[P008] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P04-544] Bacterial Community Analysis in Spider Mites: Toward Microbiota-Based Solutions for Marine Pest Contamination

○Futaba Doi¹, Kazuki Toyoda¹, Naoki Takeda¹, Takeshi Suzuki¹, Tetsushi Mori¹ (1. Tokyo University of Agriculture and Technology (Japan))

Keywords:

Mites,Seafood contamination,Life cycle,Microbiota

Marine environments harbor diverse arthropod communities, including marine mites (Halacaridae), one of the oldest secondarily marine animal lineages. With over 1,000 described species globally, these microscopic organisms (150-1000 μm) inhabit various marine substrates from intertidal zones to depths exceeding 5,000 meters. Unlike terrestrial mites forming parasitic relationships, marine mites function as substrate associates and benthic predators, raising concerns about seafood safety and consumer health. While standard seafood processing likely removes most mites, their microscopic size presents detection challenges, with higher risk for individuals with arthropod allergies consuming raw products. Environmental bacteria colonize marine organisms, providing unique adaptation characteristics. Environmental changes resulting in forced adaptation could promote marine mite contamination risk in seafood products. Physical removal is challenging, necessitating new approaches to naturally eliminate them, particularly from aquaculture communities. We investigated whether marine mite contamination could be prevented by naturally redesigning mite microbiota. As proof-of-concept, we analyzed bacterial communities throughout the life cycle of two terrestrial economically important spider mite species: the two-spotted spider mite (TSSM) and Kanzawa spider mite (KSM), both reared on green bean leaves. Assuming symbiotic bacteria essential for survival are present at all developmental stages, we examined all life stages and prepared samples before and after feeding to identify postnatally acquired bacteria. Analysis covered eight stages: eggs; larvae before and after feeding; first- and second-instar nymphs; adults immediately after molting; 1-day-old adults; and 5-day-old adults. To minimize contamination, mite egg surfaces were washed using 0.1% Tween 20 and collected. DNA was extracted from each sample, and 16S rRNA V3-V4 region was analyzed using Illumina NextSeq 1000 sequencing. Using reads with Q-score ≧35 and length ≧300 bp, OTU clustering was performed at 97% similarity, identifying bacterial species with relative abundance ≧1%. Wolbachia accounted for 70–90% of bacterial community at all developmental stages in both species, establishing it as the primary symbiotic bacterium. Ten bacterial species were detected in eggs of both species, suggesting symbiotic bacteria maintenance across generations. Seven bacterial species were identified in TSSM and six in KSM; however, these were absent from eggs and pre-feeding larvae, present only in post-feeding samples, indicating postnatal acquisition from food sources. Future research will focus on determining absolute bacterial abundance, in vivo localization, survival rates, and elucidating host-bacterial interactions. This study provides fundamental insights for innovative and natural pest control approaches addressing the growing problem of mite contamination in marine environments and seafood safety.