Toxicological and biochemical effects of some safe compounds on fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

<ns3:p>The fall armyworm, Spodoptera frugiperda, is known as one of the most important insect pests in Egypt, depending on the wide host range and quick adaptation to climatic factors. The current study aimed to evaluate the toxic and biochemical effects of photosensitizer (magnesium chlorophillin (Mg-Chl), nanocomposites (graphene oxide (GO) nanomaterial over magnesium chlorophillin (Mg-Chl/GO), and essential oil of lemongrass (Cymbopogon citratus) against the second instar larvae of S. frugiperda. Four concentrations of three compounds were tested. Thereafter, some biochemical aspects of the surviving second instar larvae of S. frugiperda after each treatment were recorded. The findings indicated that the larval mortality rate exhibited a positive correlation with increasing both the concentration of tested compounds and exposure duration. The mortality percentage of the Mg-Chl/GO composite was higher than magnesium chlorophillin (Mg-Chl) and essential oil of lemongrass. According to LC50 values, Mg-Chl/GO (LC50=0.0005 ml/ l) as more effective than Mg-Chl (LC50=0.227 ml/ l) and C. citratus essential oil (LC50=7.5 ml/ l). Also, according to LT50 values, the Mg-Chl/GO nanocomposite had higher time-response effectiveness on S. frugiperda larval mortality % than the photosensitizing Mg-Chl treatments. At the exposure of 1 hour of light, LT50 there was 2.306 and 2.578 days at Mg-Chl/GO (10-2) and Mg-Chl (10-2), respectively. The three tested compounds demonstrated a markedly significant reduction in total protein levels when compared to the control group. Detoxification enzyme activity in treated larvae indicated a significant effect on acetylcholinesterase (AchE), GST, and CaE compared control.</ns3:p>