Role of the serine/threonine kinase polo in pupal-adult metamorphosis and oogenesis of Lasioderma serricorne female.

The serine/threonine-protein kinase polo plays a crucial role in regulating the cell cycle and mitosis in insects. While the cigarette beetle, Lasioderma serricorne, is a globally distributed pest threatening stored products, the functions of its polo gene remain largely unexplored. This study investigates the polo gene to elucidate its role in the development and reproduction of L. serricorne. The Lspolo gene, which encodes a protein containing a catalytic serine/threonine kinase domain and polo box domains, was identified and cloned. Spatio-temporal expression analyses indicated that Lspolo is predominantly expressed in the ovary, peaking in 5-day-old adult females. RNA interference (RNAi)-mediated knockdown of Lspolo caused significant disruptions in the pupal-adult transition, leading to lethal molting defects and abnormal elytra formation. Lspolo knockdown also significantly reduced the expression of wing development-associated genes. Furthermore, Lspolo silencing resulted in pronounced ovarian abnormalities, including disrupted oocyte maturation, impaired vitellogenesis, and structural anomalies in follicular cells. Additionally, a significant decrease in vitellogenin content and marked downregulation of LsVg and LsVgR gene expression were observed. These cellular and morphological deficits induced a notable decrease in female fecundity, a 6.7-day shorter oviposition period, reduced egg production, and a 34% decrease in offspring hatching rate. Our findings demonstrate that Lspolo plays a crucial role in pupal-adult metamorphosis and oogenesis in L. serricorne, highlighting its potential as a molecular target for RNAi-based pest control strategies.