棉铃虫幼虫感染棉铃虫微孢子虫后的组织病理变化

Observations on histopathology of tissue infected by Nosema sp. (Microsporida) in Helicoverpa armigera (Hübner) larvae

1997年田间调查时发现一种寄生于棉铃虫Helicoverpaarmigera (H櫣ｂｎｅｒ)的微孢子虫Nosemasp .,它对棉铃虫有较强的致病力并可经卵垂直传播。利用透射电镜对棉铃虫幼虫感染该微孢子虫后的组织病理变化进行了初步观察。结果表明 :该微孢子虫可侵染棉铃虫的中肠、马氏管、脂肪体、神经等组织 ;侵染后可导致寄主中肠的微绒毛脱落 ,线粒体内脊排列方向发生变化 ,线粒体整体发生变形并最终瓦解 ;内质网发生断裂 ;细胞核体积变小并变形 ,但该微孢子虫并不入侵细胞核 ;马氏管膨大 ,边缘向外突出隆起 ;神经细胞的细胞核变成长条形 ,细胞界线模糊 ;在神经细胞内也发现了微孢子虫孢子 ,证明该微孢子虫也入侵寄主神经细胞。

A previously unknown microsporidian pathogen Nosema sp.in Helicoverpa armigera(Hübner)is described. It invaded H.armigera larvae and could be transmitted vertically to their offspring. This study investigates ultrastructural changes of infected host cells using electron microscopy. The results indicate that the pathogen occurs in the midgut, fat bodies, malpighian tubules and nerve cells of the host. After invading the host, it causes the micro-villi of the midgut to fall off, the nucleus to become smaller and the shape of the nucleus to change. The malpighian tubules become swollen and the nucleus of nerve cells becomes elongated and their boundaries indistinct. The mitochondria become smaller and the cristae become aligned parallel or at an angle to the long axis of the mitochondria. The endoplasmic reticulum is disordered, however, the pathogen did not invade the nucleus.