The transcriptome reveals the potential mechanism of 20E terminating diapause in cotton bollworm, Helicoverpa armigera.

BACKGROUND

Diapause is a crucial adaptive strategy employed across numerous insect species, endowing them to survive in unfavorable environments. Helicoverpa armigera, one of the most destructive pests globally, undergoes diapause in the pupa stage, which is essential for its survival during the overwintering period and ultimately determines the following year's population density. 20E is a primary hormone that regulates the process of pupae diapause. However, a comprehensive analysis of the mechanisms by which 20E regulates the initiation and termination of diapause in H. armigera remains lacking.

RESULTS

In the present study, exogenous 20E was initially administered to diapausing pupae, and the results demonstrated that 20E markedly enhanced the development and eclosion rate of diapausing pupae, indicating that 20E treatment effectively terminated the diapause of H. armigera. Subsequently, RNA-Seq was employed to construct a comprehensive transcriptome map of the 20E-induced termination of diapause. The results demonstrated that there were 2836 differentially expressed genes, including 1315 genes that were upregulated and 1521 genes that were downregulated, in the 20E injection group relative to the control group. KEGG and GO enrichment analysis showed that these genes were associated with various metabolic pathways. Moreover, additional analysis revealed that the majority of the pivotal genes associated with metabolism (including glycolysis/gluconeogenesis, glycerolipid, amino sugar and nucleotide sugar metabolism), cell signaling pathways (such as insulin, Wnt, MAPK signaling pathways), the cell cycle, and stress resistance exhibited altered expression following 20E injection. These findings suggest that 20E exerts its primary influence on metabolic processes, cell signaling pathways, cell cycle, and stress resistance during the termination of diapause.

CONCLUSIONS

Our study presents a systematic and comprehensive analysis of the genes associated with 20E-induced diapause termination, thereby providing a foundation for elucidating the molecular mechanism of 20E regulating diapause. Furthermore, the findings lend support to the utilization of ecdysone analogs as pesticides in diapause-based pest management.