Uncovering the Chemosensory System of a Subterranean Termite, Odontotermes formosanus (Shiraki) (Isoptera: Termitidae): Revealing the Chemosensory Genes and Gene Expression Patterns

SIMPLE SUMMARY: In order to sense the numerous chemical signals from their surroundings, insects have developed complex olfactory systems and olfactory mechanisms involving a wide range of chemosensory genes. Olfaction therefore plays an integral role in directing and regulating all insect behaviors and activities. Termites possess significant ecological significance due to their eusocial nature; that is, they use intricate chemical communication mechanisms to coordinate colony organization and regulate social behavior. In this study, a transcriptomic analysis of Odontotermes formosanus workers was performed to uncover candidate chemosensory genes. Forty-two candidate chemosensory genes were identified, and the relative expression profiles of these candidate genes were investigated. This study reveals new directions for the study of chemosensory genes and uncovers the molecular underpinnings of the functional olfactory system in termites, which will lead to the green pest management of termites in the future. ABSTRACT: Termites are eusocial insects. Chemical signals between colony members are crucial to the smooth running of colony operations, but little is known about their olfactory system and the roles played by various chemosensory genes in this process. Chemosensory genes are involved in basic olfactory perception in insects. Odontotermes formosanus (Shiraki) is one of the most damaging pests to agricultural crops, forests, and human-made structures. To better understand the olfactory system and the genes involved in olfactory processing in O. formosanus, we produced a transcriptome of worker termites. In this study, we identified 13 OforOBPs, 1 OforCSP, 15 OforORs, 9 OforGRs, and 4 OforSNMPs. Multiple sequence alignments were used in the phylogenetic study, which included data from other termite species and a wide variety of insect species. Moreover, we also investigated the mRNA expression levels using qRT-PCR. The significantly high expression levels of OforCSP1, OforOBP2, OforOR1, and OforSNMP1 suggest that these genes may play important roles in olfactory processing in termite social behavior, including caste differentiation, nestmate and non-nestmate discrimination, and the performance of colony operations among members. Our research establishes a foundation for future molecular-level functional studies of chemosensory genes in O. formosanus, which might lead to the identification of novel targets for termite integrated pest management.