Role of the clock gene period in regulating circadian rhythm of courtship vibrations in Nilaparvata lugens.

Nilaparvata lugens, the brown planthopper (BPH), is a notorious pest threatening rice production across Asia. The heavy reliance on synthetic insecticides for control has led to resistance and raised ecological concerns. Substrate-borne vibrational communication, integral to species-specific mate recognition systems in insects, presents a potential avenue for pest management through mating disruption. However, the molecular mechanisms regulating vibrational signals in BPH remain poorly understood. In this study, we cloned and analyzed the clock gene period from BPH. The open reading frame of Nlper is 3708 bp, encoding a 1235-amino acid protein with two conserved domains: the Per-ARNT-Sim domain and the Period protein 2/3C-terminal region. It shares a closer evolutionary relationship with Laodelphax striatellus and Frankliniella occidentalis. Spatiotemporal expression analysis showed that Nlper was consistently expressed across all life stages and adult tissues, with the highest levels in macropterous males and male head, respectively. Rhythmic expression exhibited significant circadian oscillations under both light-dark and constant darkness conditions, peaking at 00:00 and reaching a trough at 12:00, with fold changes ranging from 2.47 to 3.39. Moreover, after dsRNA injection, Nlper expression decreased by 77.21%-84.26% from day 2 to day 5, disrupting the circadian oscillation of female vibrational signals (FVS) and causing a significant peak shift, along with a 30.56% reduction in FVS frequency on day 5. These findings underscore the essential role of Nlper in regulating the circadian rhythm of courtship vibrational signals, deepening our understanding of the genetic basis of insect communication and opening new possibilities for innovative pest management approaches.