| The Chinese white pine beetle, Dendroctonus armandi Tsai et Li, is the most destructive forest pest in the Qinling Mountains. The life cycle of Chinese white pine beetle is 1-2 generations per year. Firstly the female adult bark beetles attacked the healthy Chinese white pine, Pinus armandi, over 30 years and constructed the egg gallery with the complement nutrition between the phloem and xylem. Then lay eggs in both sides of egg gallery. The larval galleries formed gradually when the larva feed. The egg gallery and larval galleries disrupts the nutrition transportation so that lead Chinese white pine to death. Althrogh there are reported on biology and ecology of Dendroctonus armandi, the structure of female reproductive organ, ovarian development and oogenesis in D. armandi have not been studied. This study aim to show the law of breeding and population dynamics, so it will proviod scientific evidence for the sustainable management in D. armandi.In this study, we examined the morphological and cytology structures of the female reproductive organ of D. armandi by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The major conclusions as follow:The female reproductive system D. armandi consists of paired ovaries and short lateral oviducts, a common oviduct, a spermatheca and accessory glands. The ovaries are made up of four egg tubes ovarioles. The lateral oviducts connect the ovary and the common oviduct, and are mesoderm in origin. The common oviduct is an invagination of the ectoderm of the seventh abdominal sternite, and its distal end is properly called the gonopore. The spermatheca, typically opening at the anterior of the genital chamber and accessory glands opening more posteriorly serve a variety of functions specific to particular species.The ovarian development of D. armandi was classified into five grades,â… grade, previous period of ovarian development (the ovarioles are colorless transparent, short and thin, and not fully development. The gland is formed, but the spermatheca is not formed.).â…¡grade, elongation period of ovarian development (the ovarioles are colorless transparent and slender; the gland is formed, but the spermatheca is not formed.)â…¢grade, previtellogenic (the ovarioles are spindle; the front of ovarioles are transparent, the basal part of them are turbidity or little yolk has deposited.)â…£grade, vitellogenic eggs (the ovarioles are cylindrical, deposited yolk accounts for one-third of length of ovarioles.)â…¤grade, ovipositing (the ovarioles are pale white and a few eggs are stored in the egg calyxes).Ovarioles of D. armandi, belonging to telotrophic-meroistic type,are divided into terminal filament, tropharium and vitellarium, of which the troharium consists of interstitial cells, nurse cells, arrested oocyes and prefollicular cells. In the apex of the tropharium, the shape of nurse nuclei is spherical; and it is heavily lobed in the basal region of the terminal chamber, which seems to supply the nutrition to the oocyte. Membranes of all nurse cells are reduced, but the membranes exist between nurse cells and interstitial cells and form a three-dimensional net. The nurse cell cytoplasm is filled with mitochondria, free ribosomes and"nuage"material. The oocyte development is asynchronous, with each oocyte being surrounded by a layer of follicular cells. Early previtellogenic arrest oocytes and profollicular cells are located at the base of the tropharium, and during vitellogenesis, yolk granule, mitochondria, Golgi complex and rough endoplasmic reticulum appear in the cytoplasm of the oocytes.
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