Abstract: 【Aim】 Coccinellidae show highly diverse feeding. This study aims to explore the relationships between olfaction-related genes in antennae and feeding divergence based on the establishment of the antennal transcriptome of Coccinella septempunctata. 【Methods】 The antennal transcriptome of C. septempunctata adults was sequenced using an Illumina HiSeq 4000 platform and subjected to assembly, annotation and comparative analysis with the previously published transcriptomes of Henosepilachna viginyioctopunctata, and the olfaction-related genes were identified. 【Results】 A total of 31 775 unigenes were obtained in C. septempunctata antennal transcriptome, 69.71% of which were annotated, and the highest number of unigenes (20 539) were annotated in the NR database. According to the annotation information, 27 olfaction-related genes including 1 odor binding protein (OBP) gene, 13 chemoreceptor protein (CSP) genes, 4 odorant receptor (OR) genes, 7 gustatory receptor (GR) genes and 2 sensory neuron membrane protein (SNMP) genes were identified. In parallel, 38 olfaction-related genes were identified in the transcriptomes of H. viginyioctopunctata, including 1 ionotropic receptor (IR) gene that was not found in C. septempunctata. Among the various types of olfaction-related genes, the proportion (13.16%) of OBP genes in the transcriptomes of H. viginyioctopunctata was higher than that  (3.70%) in the antennal transcriptome of C. septempunctata, while the proportion (25.93%) of GR genes in the antennal transcriptome of C. septempunctata was higher than that  (13.16%) in the transcriptomes of H. viginyioctopunctata. 【Conclusion】 The number of olfaction-related genes in the antennae may not make a predominant contribution to insect feeding divergence. This study obtained the antennal transcriptomic data of C. septempunctata and preliminarily explored the relationships between olfaction-related genes and feeding divergence in ladybirds, providing information for understanding the molecular basis of feeding divergence in ladybirds and even in insects.

Key words: Coccinella septempunctata, antennal transcriptome, feeding divergence, gene annotation, olfaction-related gene