Molecular and Functional Characterization of a Polo-Like Kinase 1 Gene in Locusta migratoria

Feeding, molting, and detoxification are crucial physiological processes in insect development. The midgut plays a central role in food digestion and nutrient absorption. Damage to the midgut can significantly inhibit insect growth. The molting is regulated by hormones such as 20-hydroxyecdysone (20E). 20E activates downstream genes involved in chitin metabolism. These genes facilitate cuticle degradation and synthesis during the molting cycle. Polo-like kinase 1 (PLK1) is an essential regulator of cell cycle progression. Although it has been extensively studied in mammals, its function in insects remains poorly understand. In this study, we identified and characterized the LmPLK1 gene in Locusta migratoria, a major agricultural pest. RNA interference targeting LmPLK1 induced atrophy of midgut and gastric ceca, impaired cuticle formation, and disrupted molting by reducing 20E titer and the expression of molting-related genes. Supplementation with 20E partially rescued cuticle separation defects, highlighting the role of LmPLK1 in modulating 20E signaling. Additionally, the knockdown of LmPLK1 increased nymph susceptibility to malathion. These findings indicate that LmPLK1 is a promising RNAi target for pest control, providing a novel strategy for managing locust populations.