霍氏啮小蜂的卵巢发育和卵子发生

Ovarian development and oogenesis in Tetrastichus howardi(Olliff )(Hymenoptera: Eulophidae)

霍氏啮小蜂是一些鳞翅目和双翅目昆虫蛹的寄生蜂。本文描述该寄生蜂从亚洲玉米螟羽化后0,6 12,18,24,30,36,42,48,54,60,66和72 h的卵巢发育和卵子发生过程。霍氏啮小蜂雌性生殖系统为典型的膜翅目姬小蜂类型,包括2个卵巢,每个卵巢通常有8-9根卵巢管,另有1对输卵管附腺,1个受精囊和1个受精囊腺等。卵黄和卵子形成于羽化后12 h,刚羽化的雌蜂不含成熟卵(成熟卵指数OI=0),成熟卵出现在羽化后24 h,成熟卵数量随后不断增加至数量较为稳定。卵巢管内卵数与雌蜂的体长和头宽呈正相关,相关系数分别为0.859和0.907。研究结果表明霍氏啮小蜂属卵育型(synovigeny)寄生蜂,本文还讨论了卵育型霍氏啮小蜂的卵成熟策略。

Tetrastichus howardi （Olliff） （Hymenoptera： Eulophidae ） is an important pupalendoparasitoid of some lepidopteran and dipteran pests. The ovary development and ovigeny pattern of T. howardi were studied in newly-emerged females at 0, 6, 12, 24, 48, 54, 60, 66 and 72 h intervals after their emergence from Ostriniafurnacalis （Lepidoptera： Pyralidae） pupae. The reproductive system of the parasitoid is typical of hymenopteran eulophids, consisting of two ovaries, each usually comprising 8 - 9 ovarioles. T. howardi possesses two obvious oviduct accessory glands, one spermatotheca and one spermatotheca gland. Oogenesis and vitellogenesis commenced on 12 hours after emergence. Mature eggs were no observed in ovaries of newly emerged female （ovigeny index --O） , and commenced on 24 hours after emergence. The number of mature eggs in ovaries initially increased and then stabilized. Number of eggs in ovaries had significant positive correlation with the body length and head width of female adult, with correlation coefficient of 0. 859 and 0. 907, respectively. The results imply that T. howardi is a synovigenic species, and egg maturation strategies of this parasitoid are discussed.