Comparative Transcriptome Analysis of the Pest Galeruca daurica (Coleoptera: Chrysomelidae) Larvae in Response to Six Main Metabolites from Allium mongolicum (Liliaceae).

Simple Summary: Galeruca daurica (Coleoptera: Chrysomelidae) has become one of the most important insect pests in the grasslands of Inner Mongolia, China. Herbivorous insects have a very close relationship with host plants, which constitute the food source, mating site, oviposition site, and habitat of all or part of their life cycle, and the digestion and utilization of nutrients and the adaptation of secondary metabolites are the key factors for insects to establish populations. In this study, after the larvae of G. daurica fed, respectively, on foods containing six different plant metabolites (three primary metabolites and three secondary metabolites), a total of 291 differentially expressed genes (DEGs) were identified compared to the solvent control, including 130, 34, 29, 21, 72, and 97 in the isoquercitrin, isoflavone, rutin, d-galactose, β-d-glucopyranose, and l-rhamnose treatment groups, respectively. GO and KEGG enrichment analysis showed that most DEGs were enriched in various metabolic pathways, implying that these six main primary and secondary metabolites in Allium plants may play crucial roles in various metabolic processes in the larvae of G. daurica. Plants are important ecological factors and food resources, which can significantly affect the occurrence and distribution of insects. The metabolites in host plants can affect the feeding, spawning, and avoidance behaviors of herbivorous insects. Galeruca daurica (Joannis) is a phytophagous pest that has seriously occurred in the desert steppe of Inner Mongolia in recent years, only infesting the leaves of Allium plants. In order to clarify the effects of plant metabolites on the gene expression in G. daurica larvae at the transcriptome level, we fed the larvae of G. daurica with Allium tuberosum leaves soaked in 10% DMSO solutions containing d-galactose, β-d-glucopyranose, l-rhamnose, isoquercitrin, isoflavone, and rutin, respectively, used the larvae fed on A. tuberosum leaves soaked in a 10% DMSO solution as the control, and screened out the differentially expressed genes (DEGs) by performing high-throughput transcriptome sequencing. The results showed that a total of 291 DEGs were identified compared to the solvent control (DMSO), including 130, 34, 29, 21, 72, and 97 in the isoquercitrin, isoflavone, rutin, d-galactose, β-d-glucopyranose, and l-rhamnose treatment groups, respectively. GO and KEGG enrichment analysis showed that most DEGs were enriched in various metabolic pathways, implying that these six main primary and secondary metabolites in Allium plants may affect various metabolic processes in the larvae of G. daurica. [ABSTRACT FROM AUTHOR]