ABSTRACT: Tabanus nipponicus is a hematophagous insect species with high activity in summer, and its midguts play a critical role in successful blood-feeding, as they are closely associated with blood meal digestion, nutrient absorption, and physiological regulation during hematophagy. In this study, midgut samples from three independent T. nipponicus individuals collected during the peak of summer activity were used for RNA-seq analysis. Prior to sequencing, total RNA was extracted under sterile and low-temperature conditions to ensure RNA integrity. Paired-end sequencing generated 43,569,311 to 46,711,652 raw reads, which were further processed for de novo assembly, yielding 8,039 unigenes. These unigenes were first aligned to the Nr database to obtain functional annotations, and the annotated unigene IDs were subsequently mapped to the GO database, being classified into three main GO categories (biological process, cellular component, and molecular function). Functional annotation revealed enrichment in metabolic processes, membrane-related biological processes, and binding/catalytic molecular activities—all of which are closely related to the physiological functions of the midgut in T. nipponicus, including the digestion and absorption of blood meals, the transport of nutrients and metabolites, and the regulation of physiological processes required for continuous blood-feeding, thereby underpinning the synthesis and secretion of anticoagulant saliva components essential for blood-feeding adaptation and microbial stress resistance. Additionally, the unigenes were aligned to the KEGG database to obtain corresponding KEGG IDs, which were then mapped to unique KOs followed by KEGG enrichment analysis to explore the key metabolic pathways involved. Future studies will focus on the key physiological processes of T. nipponicus midguts, including anticoagulation, blood meal digestion, antioxidant defense, and microbial resistance.
