Identification and coordinated expression of perilipin genes in the biological cycle of sunn pest, Eurygaster maura (Hemiptera: Scutelleridae): Implications for lipolysis and lipogenesis

The sunn pest, Eurygaster spp., is one of the most destructive pests of grains in Asia, Europe and Africa. The nymphs and adults feed voraciously in the field by late-spring, followed by migration of adults into mountains for diapause, which includes estivation by late summer and hibernation during winter. Adults migrate back to the field by the end of diapause in mid-spring, where they mate and lay eggs. To understand how sunn pest survives and maintains basic metabolic functions without feeding for 7 months during diapause, this study focused on lipid metabolism as the major source of energy production, and the primary organ of lipid metabolism, the fat body. Studies on lipid metabolism revealed two major factors referred to perilipin protein family, Lipid Storage Droplet Protein 1 (LSD1) and Lipid Storage Droplet Protein 2 (LSD2), which are involved in hydrolysis and accumulation of lipids, respectively. In this study, two LSD (EmLSD1-2) orthologues in the hemimetabolous Eurygaster maura were identified. EmLSD1 and EmLSD2 genes were expressed in multiple tissues, but primarily in fat body. Both genes were continuously expressed throughout the insect's life cycle but peaked in the 4th nymphal stage. Their expression patterns were in accordance with the biological roles of LSDs. EmLSD1 expression peaked in non-feeding stages supporting its lipolytic role, while the highest level of EmLSD2 expression was in feeding stages supporting its lipogenetic role. Expression patterns of both genes differed in females and males. Overall, expression patterns of EmLSDs provide clues to understanding the interesting life cycle of sunn pest.