球孢白僵菌在红火蚁体表侵染的扫描电镜观察

Observation on infection process of Beauveria bassiana on cuticle of the red imported fire ant,Solenopsis invicta Buren(Hymenoptera:Formicidae),using scanning electron microscope

利用扫描电镜观察了球孢白僵菌Beauveria bassiana Bb04菌株分生孢子对红火蚁Beauveria bassiana工蚁体壁的侵染过程。结果表明:分生孢子多分布在红火蚁工蚁节间膜、胸部的褶皱、气门、体壁的凹陷部位、刚毛窝附近,以及着生较密刚毛的足上。萌发的分生孢子在节间膜以及体表缝隙、刚毛窝及刚毛稀少的凹陷部位、胸部褶皱和足胫节处入侵。分生孢子在附着12h后开始萌发,接种后18h附着在节间膜处的孢子首先侵入成功,接种后24h刚毛窝附近孢子萌发入侵,接种后60h胸、腹和足等部位的孢子均成功穿透侵入表皮。分生孢子可以直接以芽管侵入表皮,也可以产生附着胞再侵入。

The infection process of Beauveria bassiana conidia on cuticle of Solenopsis invicta was observed using scanning electron microscope （SEM）. The results showed that most of conidia were deposited on intersegmental membranes,folded regions on thorax,spiracles,cavities,setae and coxae of legs. The germinated conidia mainly invaded the worker cuticle from intersegmental membranes,as well as setae,cuticle cavities,rugous regions on cuticle and tibiae. The conidia adhered on worker surface began to germinate at 12 h after inoculation. The first penetration of germinated conidia occurred in intersegmental membrane at 18 h after inoculation,followed by penetration of conidia around setae at 24 h after inoculation. Conidia on all kinds of surface topography including the thorax,abdomen and legs successfully invaded into the cuticle and resulted in infection at 60 h after inoculation. The germinated conidia of the isolate either invaded the cuticle directly with germ tube or invaded the cuticle by producing appressorium during the course of infection.