Effect of fipronil on brain and muscle ultrastructure of Nilaparvata lugens (Stål) (Homoptera: Delphacidae).

The ultrastructure of Nilaparvata lugens brain cells was damaged by treatment at different fipronil concentrations. The cell showed swollen mitochondria and vacuolization, but no mitochondrial cristae. Rough endoplasmic reticulum (RER) fragmentation and degranulation were seen. The dilatation of endoplasmic reticulum cisterns was very prominent, and the predominant lamellar RERs were arranged chaotically. The Golgi apparatus demonstrated obvious changes in configuration, as dilated with closed cisternae and atypical vesicles. The mitochondria mainly showed large vacuolization in muscles. Nuclear degeneration and condensation and increased numbers of large hydropic vacuoles and lysosomes were observed. It was concluded that the effect on cellular components was fipronil-specific. Changes in cellular ultrastructure seem to be an appropriate ecotoxicological indicator of the insecticide's efficacy.