Gao Ying, Xie Ying Ping, Xiong Qi, Liu Wei Min, Xue Jiao Liang
School of Life Science, Shanxi University, Taiyuan, China.
Institute of Applied Biology, Shanxi University, Taiyuan, China.
PLoS One. 2015 Jan 28;10(1):e0117428. doi: 10.1371/journal.pone.0117428. eCollection 2015.
The histopathological changes of the second instar nymph of the mealybug Phenacoccus fraxinus infected with Lecanicillium lecanii strain 3.4505 were investigated using light, scanning and transmission electron microscopy. The results demonstrated that L. lecanii 3.4505 could infect P. fraxinus in a short period. At 24 h post-inoculation, the conidia of L. lecanii 3.4505 adhered to the indented gloves or intersegmental folds of the insect body surface. Subsequently, the germinated conidia produced germ-tubes, appressoria and extended hyphae, which tightly adhered to the cuticle. Penetration of cuticle could be achieved either by peg form appressoria or directly by hyphae. Also, the conidia and hyphae could secrete massive mucilages causing visible damage to the host cuticle. After 48 h, the body wall, tissues and organs, including cuticle, trachea, fat body, muscle, Malpighian tubules and nerve ganglion, were destroyed by ramification of hyphae as a result of infection. The endoplasmic reticulum hypertrophied and formed obvious fingerprint agglomerates, and the mitochondria swelled and deformed in the haemocytes. Finally, the mycelium fully occupied the entire haemocoel. The entire bodies were wrapped in a white mycelium, with the mycelium extending radically outward.
利用光学显微镜、扫描电子显微镜和透射电子显微镜，研究了感染蜡蚧轮枝菌3.4505菌株的白蜡绵粉蚧二龄若虫的组织病理学变化。结果表明，蜡蚧轮枝菌3.4505可在短时间内感染白蜡绵粉蚧。接种后24小时，蜡蚧轮枝菌3.4505的分生孢子附着在昆虫体表的凹陷处或节间褶皱处。随后，萌发的分生孢子产生芽管、附着胞并延伸出菌丝，这些菌丝紧紧附着在角质层上。角质层的穿透可通过附着胞形成的钉状结构或直接由菌丝实现。此外，分生孢子和菌丝可分泌大量黏液，对宿主角质层造成明显损伤。48小时后，由于感染，菌丝分支破坏了包括角质层、气管、脂肪体、肌肉、马氏管和神经节在内的体壁、组织和器官。血细胞中的内质网肥大并形成明显的指纹状聚集体，线粒体肿胀并变形。最后，菌丝体完全占据整个血腔。整个虫体被白色菌丝体包裹，菌丝体呈放射状向外延伸。
