Neurotoxic effect of spinetoram on Spodoptera littoralis (Boisd.) Larvae

Document Type : Original Article

Authors

1 Department of Entomology, Faculty of Science, Ain Shams Univ., Cairo, Egypt

2 Plant Protec. Res. Instit., Agric. Res. Center, El Dokki, Giza, Egypt

Abstract

The present study was conducted to evaluate the neurotoxic effect of spinetoram on Spodoptera littoralis (Boisd.) larvae. Testing different concentrations of this green chemical compound against 4th instar larvae showed that spinetoram is a fairly toxic with LC50 (1.11 ppm). Its neurotoxicity was manifested as evident histopathological changes in the structure of neurosecretory (NSCs) and ordinary nerve cells (NCs) of suboesophageal ganglion (SOG) of this pest after treatment with LC50 of this compound.
Photo and electron micrographs of suboesophageal ganglion (SOG) of treated S.littoralis larvae with LC50 of spinetoram showed aggregation of neurosecretory granules in the oval, triangle and irregular shaped neurosecretory cells but not in the round shaped cells. Also, the SOG of treated larvae showed an apparent vacuolization and increase in the size of cytoplasm, abundance and aggregation of mitochondria in nerve cells and all kinds of NSCs (round, irregular, triangle and oval) and the appearance of multivesicular bodies in the cytoplasm of neurosecretory cells.    

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