Toxicity of Hottentotta saulcyi venom against Sesamia nonagrioides on sugarcane plants

To evaluate the toxicity of Hottentotta saulcyi</em> venom on Sesamia nonagrioides</em>, we investigated the larval mortality, detoxification enzyme activity and histopathological alterations of the S. nonagrioides</em> organs. Venoms were injected into the larvae at five doses (0.15µg, 0.35µg, 0.5µg, 0.75µg and 1µg; fifteen larvae per each dose) and the doses causing death were recorded during the experiment. This study demonstrated that H. saulcyi</em> venom was able to cause external symptoms that eventually led to death of the intoxicated larvae. Moreover, this venom strongly inhibited glutathione S-transferases (GST) activity. Our data highlighted the relationship between the activity of GST enzyme and larval mortalities, so that the inactivation of this enzyme by scorpion venom may be responsible for the increasing the larval mortality. In the present study, the damage of midgut epithelium and malpighian tubules has been directly visualized and documented using histopathology methods. Clear histopathological alterations of intoxication were observed for all larvae injected with 1µg doses of venom, including a distinctive lysing and disorganizing of midgut epithelial cells that coupled with a progressive loss of the peritrophic membrane and the disappearance of microvilli.