Abstract: 【Aim】 To investigate the ovarian developmental process of female adults of Monochamus alternatus, categorize the ovarian development of M. alternatus from the perspective of age, and judge the developmental status of female adults trapped by attractants in the field, so as to provide a reference for effective prevention and control of M. alternatus. 【Methods】 The mated and unmated female adults of M. alternatus at the 0-, 5-, 10-, 15-, 20-, 30-, 40- and 15-day-old, and the female adults trapped by attractants were dissected to observe the ovarian development. 【Results】 The ovarian developmental process of female adults of M. alternatus can be divided into five stages: prophase (0-5-day-old): the ovariole is transparent and slender, and there is no egg yolk deposition; egg yolk precipitation stage (5-15-day-old): there are a few milky white and yellowish immature eggs in the ovariole; ovarian maturity stage (15-20-day-old): ovariole contains a large number of fully mature eggs, which are long spindle-shaped, yellow and full of luster; oviposition peak stage (20-40-day-old): mature eggs are piled up in the egg calyx, and there are eggs to be laid in the median oviduct and lateral oviduct; and aging stage (≥40-day-old): ovariole, egg calyx and oviduct gradually atrophy. After mating, the female adults can produce fertilized eggs, and the egg calyx is enlarged and visible. The unmated females can’t produce fertilized eggs, and the eggs can’t be produced when they are accumulated in the oviduct, and the egg calyx is not fully differentiated and the shape is invisible. The results of field trapping showed that there were significant differences in the number of trapped female adults at different day-old ages, and the proportion of the female adults in the oviposition peak stage was the most, accounting for 5490%±550% of the total. The female adults at the ovarian maturity stage, aging stage and egg yolk precipitation stage were relatively few, accounting for 31.37%±5.52%, 11.76%±1.54% and 1.96%±0.51% of the total, respectively. No female adults at the prophase were lured. 【Conclusion】 Female adults of M. alternatus develop to sexual maturity at the 15-20-day-old age, and mating behavior can promote the ovarian development of female adults of M. alternatus. Attractants can trap a large number of rigid mature M. alternatus, which is of positive significance for reducing the oviposition of M. alternatus, the occurrence base of the next generation and the transmission probability of Bursaphelenchus xylophilus.

Key words:  Monochamus alternatus; ovarian development, age, attractants, trapping