Gene Expression Across Tribolium castaneum Life Stages: A Search for Pest Management Genes

The red flour beetle, Tribolium castaneum, is an agricultural pest damaging post-harvest products, such as grains and cereals. Infestations are commonly treated with phosphine fumigation, and consequently many populations have developed resistance. Therefore, new pest control strategies are needed for stored product beetles like T. castaneum. On the forefront are molecular-based strategies, such as RNA interference (RNAi) and CRISPR. Both technologies require well-designed templates, specific to target genes. It is important that target genes are specific to a small range of pest insects. We seek to identify genes critical to survival, or contributing to the development of phosphine resistance. To this end, we used RNA-sequencing and analysis (RNA-seq) to identify differentially expressed genes in the four major developmental stages (adult, egg, larvae, pupae), and filtered by level of expression. We used WGCNA network analysis to find genes with expression values significantly correlated with life stage, to isolate interesting functional groups or gene families that have potential or important implications in pest control strategies. We found nine genes with moderate expression shared among all life stages, 138 shared between adult and larval stages (feeding stages), and 273, 167, 139, and 14 unique to each stage, adult, egg, larvae, pupae respectively. We then filtered the highest expressed genes and found 12 genes common to all life stages, namely genes involved in metabolism and transcription. Network analysis isolated three significant modules of genes. A compilation of these data provided a list of potential candidate genes to screen for pest management of T. castaneum.