College of Life Science, Shanxi University, Taiyuan 030006, China.
Micron. 2013 Jan;44:303-11. doi: 10.1016/j.micron.2012.08.002. Epub 2012 Aug 18.
The aim of this study was to better understand the pathogenesis of the entomopathogenic fungus Beauveria bassiana (Balsamo) strain TST05 observed on the peach fruit moth (Carposina sasakii (Matsumura)), an important orchard pest. The morphological and ultrastructural characterization of the mature larvae of C. sasakii infected by B. bassiana was investigated by using light, scanning and transmission electron microscopy. The results of the study show that B. bassiana TST05 infected the host larvae mainly by penetrating the integument. The conidia of the fungus adhere easily to the area around the mouthparts and to the basal area around the acanthae on the thorax and abdomen. Observations of the host's defensive response to the fungal attack indicated that dark spots appeared on the cuticle and that melanization appeared in the hemocoel. After overcoming the host's defense system, the pathogen grew and reproduced primarily in the hemocoel. The infection spread sequentially to the internal tissues, e.g., fat body, muscle, Malpighian tubules, gut and even the silk gland. Ultimately, the larval internal organs and tissues were damaged very extensively. Finally, the fungus emerged through the cuticle of the dead insect and released conidiophores that could act as new pathogens to infect other larvae.
本研究旨在更好地了解桃小食心虫（Carposina sasakii (Matsumura)）上观察到的虫生真菌球孢白僵菌（Beauveria bassiana (Balsamo)）菌株 TST05 的发病机制，桃小食心虫是一种重要的果园害虫。本研究采用光学显微镜、扫描电子显微镜和透射电子显微镜对被 B. bassiana 感染的成熟 C. sasakii 幼虫的形态和超微结构进行了研究。结果表明，B. bassiana TST05 主要通过穿透体壁感染宿主幼虫。真菌的分生孢子容易附着在口器周围区域和胸部及腹部刚毛基部周围的基区。对宿主对真菌攻击的防御反应的观察表明，表皮出现黑斑，血腔出现黑化。在克服宿主防御系统后，病原体主要在血腔中生长和繁殖。感染依次传播到内部组织，如脂肪体、肌肉、马氏管、肠道，甚至丝腺。最终，幼虫的内脏器官和组织受到广泛破坏。最后，真菌通过死亡昆虫的体壁穿出并释放出可以作为新病原体感染其他幼虫的分生孢子梗。
