Characterization and RNA interference-mediated silencing of tryptophan 2,3-dioxygenase gene in Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae)

Dried fruit beetle, Carpophilus hemipterus (Linnaeus, 1758) (Coleoptera: Nitidulidae), is a serious pest of ripened fresh fruit in the orchard and dried fruit in postprocessing storage. Despite the economic impact and widespread distribution of C. hemipterus, there is a lack of functional genomics research seeking to elucidate features of molecular physiology for improved pest management. Here, we report the characterization of the gene named Vermilion in C. hemipterus (ChVer) that encodes for tryptophan 2,3-dioxygenase. The Vermilion is frequently used as a visual marker for genomics approaches as tryptophan 2,3-dioxygenase is involved in the biosynthesis of eye coloration pigments in insects. We identified 1628 bp long full-length transcript of ChVer from transcriptomic database of C. hemipterus. The expression analysis among adult body parts revealed peak ChVer expression in head compared to thorax and abdomen, which is consistent with its role. Among the C. hemipterus developmental stages, peak ChVer expression was observed in first instar larva, second instar larva, and adult male stages, whereas the lowest levels of expression were seen in third instar larva, prepupa, and pupa. The nanoinjection of ChVer double-stranded RNA in larval C. hemipterus resulted in a significant reduction in ChVer transcript levels as well as caused a loss of eye color, that is, the white-eyed phenotype in adults. Characterization of visually traceable marker gene and robust RNA interference response seen in this study will enable genomics research is this important pest.