1st Place: Gene expression profiling of diapausing Euschistus stink bugs

Diapause is a neurohormonal mechanism of developmental suppression to survive unfavorable conditions and synchronize insect development. Euschistus stink bugs (Heteroptera: Pentatomidae) are important pests in the Americas. They express a facultative adult diapause induced by short-day conditions in the immature stages, allowing synchronization of their development and reproduction to resource availability (often crops). Despite their importance, a molecular characterization of diapause is still lacking for Euschistus. Thus, our objectives were to identify diapause-associated candidate genes using RNAseq of female ovaries of the species Euschistus taurulus. Insects were exposed to either a short daylength (14 h dark and 10 h light) or a long daylength (14h light and 10h dark) at 25ºC. RNA was extracted from dissected ovaries, followed by cDNA library preparation and sequencing by Illumina NextSeq 2000. De novo transcriptome assembly was performed, eventually resulting in the annotation of 13,647 genes, 1,680 of which were differentially expressed between different daylength conditions. The most promising candidate genes were related to two major pathways, juvenile hormone (JH) and insulin signaling (IS). The key genes related to JH are the nuclear receptor FTZ-F1, juvenile hormone epoxide hydrolase, and farnesyl pyrophosphate synthase; for IS, we found the gene locus insulin-related peptide. We conclude that in Euschistus stink bugs, facultative diapause genes are associated with energy storage and development. These data broaden our knowledge about the molecular features of stink bug diapause and offer promising targets for future bio-rational management approaches.