Core Symbiont Loss and Serratia Expansion Coincide with Oxidative and Ionic-Stress Responses under Chronic Imidaclothiz Exposure in Honey Bees
Chronic oral exposure to imidaclothiz impairs honey bee health prior to overt toxicity, yet the associated microbiome signals remain insufficiently defined. In this study, worker honey bees were subjected to a chronic oral exposure gradient, and gut microbiota were profiled using 16S rRNA amplicon sequencing. Exposure induced a clear dysbiosis signature characterized by reduced microbial richness, community restructuring, depletion of core symbionts (Bifidobacterium and Lactobacillus), and expansion of Serratia. Host biochemical assays indicated concurrent oxidative stress (decreased superoxide dismutase activity) and ionic imbalance (increased Na/K-ATPase activity). Serratia marcescens expansion was independently validated by luxS-targeted qPCR. These data provide a microbiome-centered toxicity signature linking chronic imidaclothiz exposure to host physiological disruption.