Abstract:  【Aim】 Galeruca daurica is a new pest with outbreak status in grasslands of Inner Mongolia, northern China. The chemosensory proteins (CSPs) of insects are a class of small and water soluble proteins whose functions are to recognize and transport environmental chemical stimuli to receptors, participating in many aspects of insect behavior. The objective of this study is to identify the chemosensory protein genes and to analyze their expression profiles in G. daurica. 【Methods】 The chemosensory protein genes in G. daurica were identified by screening the transcriptome data of G. daurica assembled in our laboratory, and qPCR was conducted to analyze their expression levels in different developmental stages (egg, 1st-3rd instar larva, pupa and adult) and adult tissues (antenna, head with antennae removed, thorax, abdomen, leg and wing). 【Results】 Ten chemosensory protein genes were identified from G. daurica, and named as GdauCSP1-10 (GenBank accession numbers: KY885471-KY885480), respectively. The amino acid sequence identity between the 10 GdauCSPs ranges from 17.27% to 62.79% with a high divergence between each other. The results of Blast in NCBI showed that GdauCSPs have the highest amino acid sequence identity (90%) with PmacCSP from Pyrrhalta maculicollis. Phylogenetic analysis showed that four of the 10 GdauCSPs were firstly clustered into a clade with PmacCSPs from P. maculicollis. The qPCR results proved that the expression levels of GdCSPs were significantly different in different developmental stages, and five GdCSPs including GdauCSP4-5, GdauCSP7-8, and GdauCSP10 had significantly higher expression levels in the adult stage than in other developmental stages while GdCSP2 had significantly higher expression level in the egg stage than in other developmental stages. GdauCSPs were also expressed in the head with antennae removed, thorax, abdomen, leg and wing besides in the antenna, and 10 GdauCSPs had different tissue expression profiles but five out of 10 GdauCSPs, including GdauCSP2, GdauCSP4, GdauCSP5, GdauCSP8 and GdauCSP9, had significantly higher expression levels in female antennae than in other tissues. 【Conclusion】 These results suggest that GdauCSPs may play different roles in the development and chemosensory process of G. daurica. This study lays the necessary foundation for further research on the physiological function of CSPs and the molecular mechanism of chemical communication in G. daurica.

Key words: Galeruca daurica; chemosensory protein, expression profile, phylogenetic analysis, qPCR