Abstract: The histopathological changes of the midgut of rice leaf folder, Cnaphalocrocis medinalis (Guenée) larvae feeding on Bt rice line“KMD1" and“KMD2" were observed using transmission electron microscopy. The results showed that cellular alternations in the midgut tissues, such as swelling of mitochondria, endoplasmic reticulum, and dilatation of intercellular spaces, fenestration or disorganization of the Golgi complex, and concentric arrangement of rough endoplasmic reticulum. The initial infected organelles were mitochondria. After longer feeding on Bt rice by the larvae, the upper portions of the cells swelled, and cytoplasm in these regions decreased in electronic density and other organelles were damaged to a certain degree, such as wiredraw of nucleus, condensation of nuclear, and the increase of number of rough endoplasmic reticulum. As the infection proceeded further, pathological changes in the mitochondrial abundant areas of basal membrane enfoldings of columnar cells and cytoplasmic projections of goblet cells became more obvious. Finally, the midgut epithelium cells disrupted and sloughed off from the basal membrane.

Key words: Cnaphalocrocis medinalis, transgenic Bt rice, midgut, histopathological change, transmission electron microscopy