白僵菌感染桑天牛幼虫致病过程的显微观察

Microscopic Observations of Infection Process of Beauveria bassian on the Cuticle of Apriona germari Larvae

为了探讨白僵菌(Beauveria bassian)与寄主桑天牛(Apriona germari)间的相互作用方式及关系,采用扫描电镜观察了白僵菌分生孢子在桑天牛幼虫体表的侵染及穿透过程。结果表明,白僵菌分生孢子接种后8 h就可以附着于桑天牛幼虫体壁,12 h时可见孢子萌发产生芽管和附着胞,16 h即可穿透幼虫体壁;桑天牛幼虫体壁不同结构区影响白僵菌分生孢子萌发速度、附着胞形成以及芽管长度,与幼虫体壁的其它结构区相比,在幼虫体表节间膜处的白僵菌分生孢子萌发早,生长更快,并且孢子不会从幼虫体表的气孔侵入;已死亡虫体的表皮、气门均发生畸变。

The infection and penetration process of Apriona germari by entomopathogenic fungi Beauveria bassian was studied using scanning electron microscopy. It was found that conidia of Beauveria. bassian attached to the cuticle of Apriona germari larvae after 8 h, and the germ tube and appressoria were formed after 12 h, penetrated through the cuticle after 16 h. Surface topography of the host had influence on infection speed, appressoria production and the length of germ tube. Apriona germari conidia on segmacoria germinated earlier and grew faster than those on other parts of the cuticle. Moreover, conidia could not penetrate through spiracles on larval cuticle. Both the cuticle and spiracle of dead A. germari larvae were malformed.