Abstract: Studying the reproductive system of the pine wood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, will identify its characteristics and life cycle. This is crucial for developing more targeted control strategies. In this study, the development of the gonads and reproductive organs were observed using microscopy, gonad dissection, and DAPI staining techniques. Second-stage juveniles (J2) had gonads composed of four primordial germ cells (Z1, Z2, Z3, and Z4) that form the adult gonads by proliferation within 72 h at 25 °C. There were subtle differences in somatic gonad cell morphology between males and females, which developed from Z1 and Z4 in third-stage juveniles (J3). These differences became more pronounced at fourth-stage juveniles (J4) and adult stages. Z2 and Z3 germ cells underwent mitosis and two rounds of meiosis, ultimately developing into male and female gametes. Female vulval precursor cells and male cloacal cells developed rapidly during the J4 stage. These results provide a basis for identifying the expression sites and biological functions of key genes regulating reproductive system development. Based on this, in situ hybridization and RNA interference (RNAi) were used to determine the function of the Bxy-glp-1 gene to show that it is involved in vulval formation and spermatogenesis. The results of this study will lay the foundation for disrupting critical stages in the reproduction of B. xylophilus.

Key words: Bursaphelenchus xylophilus, Reproductive system, Gonad, Notch, Bxy-glp-1