Molecular and Functional Characterization of a Polo-Like Kinase 1 Gene in <i>Locusta migratoria</i>

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 <i>LmPLK1</i> gene in <i>Locusta migratoria</i>, a major agricultural pest. RNA interference targeting <i>LmPLK1</i> 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 <i>LmPLK1</i> in modulating 20E signaling. Additionally, the knockdown of <i>LmPLK1</i> increased nymph susceptibility to malathion. These findings indicate that <i>LmPLK1</i> is a promising RNAi target for pest control, providing a novel strategy for managing locust populations.