Considerations on the reproductive capacity of Dryocosmus kuriphilus Yasumatsu (Hymenoptera : Cynipidae)

Ovaries of Dryocosmus kuriphilus Yasumatsu, an important pest of chestnut trees in Japan, were examined in 100 specimens. This Cynipid belongs to the preovigenic species, and the development of eggs in the ovaries is of polyootene type. Positive correlation exists between the size of this Cynipid and the ovarian development. The number of ovarioles (or egg tubules) in a single ovary varies considerably, in the bulk of specimens examined the number being 60 to 69. The ovariole number of the left ovary : usually differs from the corresponding one of the opposite side, and only 6 specimens out of 100 were observed having the same number of ovarioles in both of the ovaries. The average number of eggs in the ovaries of one individual was 300, the maximum being 599. The fact would suggest that this Cynipid has the reproductive capacity of ovipositing more than 300 eggs during her short life (about 2.5 days).100個体のクリタマバチに就いて, 卵巣の観察を行つた. クリタマバチは完全な preovigenic species で, 卵巣内の卵の発育状態から見れば polyootene type に属する. 体の大小と卵巣の発育状態との間には正の相関があるようである. 卵巣を構成する卵巣小管数の変異ばかなり著しいもので, 60～69本の個体が最も多く, 左右の卵巣を比較する場合, その卵巣小管数が左右同数のものは極めて僅かで6%に過ぎない. 1個体の卵巣内の成熟卵数は平均300個位で, 正常な個体はこれ位の数の卵を産むことが予想される