玫烟色棒束孢侵染小菜蛾的透射电镜观察
Observation of infection process of Isaria fumosorosea to Plutella xylostella with transmission electron microscopy
雷妍圆1,3**,何余容1***,吕利华2
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作者单位：1华南农业大学资源环境学院广州510642；2广东省农业科学院植物保护研究所广州510640；3中国农业科学院蔬菜花卉研究所北京100081
中文关键词：小菜蛾，玫烟色棒束孢，侵染过程，增殖方式，透射电镜
英文关键词：Plutella xylostella, Isaria fumosorosea, infection process, propagation ways, transmission electron microscopy
中文摘要： 利用透射电镜观察了玫烟色棒束孢Isaria fumosorosea (=Paecilomyces fumosoroseus)对小菜蛾Plutella xylostella (L.)的侵染过程及菌体在虫体内的增殖方式。以浓度为1×107孢子/mL的孢子悬浮液接种小菜蛾4龄幼虫, 在透射电镜下对虫体各部位的观察结果表明：接种后1 h玫烟色棒束孢菌株EBCL 03011的分生孢子开始萌芽，至4 h可观察到附着孢的形成和穿透，接种后24 h已普遍侵入体腔。玫烟色棒束孢在寄主表皮和体腔内，以菌丝段出芽生殖、菌丝分隔及菌丝段分隔3种方式大量增殖，主要以颗粒状的菌丝段在寄主体腔内扩散，菌丝段在穿透表皮和体腔内增殖过程中伴随着机械压力和酶的活动。
英文摘要： To demonstrate the process of infection of Plutella xylostella(L.) (Lepidoptera: Plutellidae) by the indigenous strain EBCL 03011 of the fungus Isaria fumosorosea (=Paecilomyces fumosoroseus) (Hypocreales: Cordycipitaceae) 4th instar larvae of P. xylostella were experimentally infected with a fungal suspension (1× 107 conidia/mL) and organs such as the integument, midgut and muscle tissues subsequently examined by transmission electron microscopy. Histopathological analyses revealed that conidia of I. fumosorosea germinated 1 h postinoculation resulting in appresorium formation ultimately penetrating the integument of P. xylostella 4 h after inoculation. The hyphal bodies had spread into the body cavity 24 h after inoculation. The penetrating hyphae of I. fumosorosea produced a number of granular hyphal bodies by budding or septation, and became distributed throughout the cuticle and hemocoel of the infected larvae. The penetration and propagation of the hyphal bodies was achieved by a combination of mechanical pressure and enzymatic action during the infection process.