Exposure to carbaryl leads to ultrastructural changes and alters activity of antioxidant enzymes in Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract. The toxic effect of carbamate insecticide carbaryl on Spodoptera exigua (Lepidoptera: Noctuidae) larvae was examined. Insects appeared to be highly sensitive to it; numerous malfunctions and malformations were observed. The first ultrastructural alterations, including biological membrane swelling, nuclear condensation, and disintegration, and abnormalities around the mitochondria were observed even before massive mortality was noted. Scanning electron microscopy revealed changes in cuticle. Carbaryl depleted the wet weight of fat body mass and changed (in most of the cases elevated) the activity of antioxidant enzymes. The majority of these malformations are rather non-specific and are common among animals exposed to xenobiotics. However, they all suggest serious disruptions in metabolism, in addition to indicating that reactive oxygen species may play an important role in the toxic effect of carbaryl.