《环境昆虫学报》

为明确莱氏绿僵菌Metarhizium rileyi CDTLJ1侵染草地贪夜蛾Spodoptera frugiperda幼虫的微观过程，利用扫描电镜、荧光显微镜及光学显微镜观察草地贪夜蛾3龄幼虫接种CDTLJ1菌株后分生孢子在幼虫体表附着、萌发、穿透及在幼虫体腔中增殖的过程。结果表明，CDTLJ1菌株分生孢子在瘤状突起结构区的萌发率为80.36%，显著高于平缓结构区的72.44%（P＜0.01）。孢子萌发后可形成芽管和附着胞，但大部分是以芽管为侵染结构。分生孢子在接种后8 h内萌发，穿透幼虫体壁的高峰期为16~24 h；接种后24~32 h幼虫蜕皮，其表面有孢子附着。最早在接种后48 h观察到幼虫体腔中出现虫菌体。接种后96 h虫体死亡，死亡后2 h，电镜下可见菌丝由寄主体内穿透体壁向外生长。CDTLJ1菌株分生孢子在离体表皮上的萌发时间为16 h，显著晚于活虫表皮上的分生孢子。

英文摘要:

In order to clarify the microscopic process of Metarhizium rileyi strain CDTLJ1 infestation in the Spodoptera frugiperda larvae and to elucidate the pathogenic mechanism of the strain, scanning electron microscope, fluorescence microscope and light microscope were used to observe the process of conidia attachment on the surface of the larvae after inoculation of the 3rd instar larvae with the strain CDTLJ1, germination and penetration, and proliferation in the larvae body cavity. The results showed that the germination rate of conidia of strain CDTLJ1 was 80.36% in strumae surface topography, which was significantly higher than 72.44% in gentle surface topography (P<0.01). Spores could form germ tubes and appressoria after germination, but most of them used germ tubes as infestation structure. Conidia germinated within 8 h after inoculation, with peak penetration into the integument of larvae at 16~24 h. Larvae moulted at 24~32 h after inoculation, and the moulted epidermis was covered with spores adhering to the surface of the protozoan. The earliest observed appearance of hyphae body in the larvae's body cavity was 48 h after inoculation. The insects died after 96 h of inoculation, Hyphae were visible in the electron microscopic field of view as it penetrated the integument and grew outward from the host at 2 h after death. The germination time of strain CDTLJ1 conidia on the isolated epidermis was 16 h, which was significantly later than that on the epidermis of live larvae.

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