Evaluation of insecticidal and antifungal activities of flavonoid compounds extractedfrom lemongrass herb (Cymbopogon citratus) and its formulation against Spodopteralittoralis and some plant pathogenic fungi

Aromatic plants are rich in phenolic compounds which known as safe alternatives to chemical pesticides.This study is made for the evaluation of insecticidal and antifungal activities of flavonoid compounds extracted from lemongrass (Cymbopogon citratus) leaves and its formulation.The yield of methanolic extract percentage was nearly 5.8% for leaves and the yield of total flavonoids precipitated was recorded 15.2% of the dry weight.The high performance liquid chromatographic (HPLC) analysis identified 15 compounds.The abundance of them were chlorogenic acid (52.62 g/ml), methy gallate (22.78 g/ml), gallic acid (21.32 g/ml), rutin (11.10 g/ml), ellagic acid (7.43 g/ml), and coumaric (6.89 g/ml), with respect to their standards.The local formulation overruns all of the laboratory investigations as soluble liquid (SL) formulation.The effectiveness of different concentrations of the methanolic extract of C. citrates on the neonates of Spodoptera littoralis was evaluated before and after formulation.The results showed that flavonoids formulation (SL) have more effects than flavonoid extract (a.i),where LC50 values were 3074.2 and 5689.3 ppm, respectively.In addition both compounds exhibit the significant reductions in all developmental stages of S. littoralis larval survival, pupation, adult emergence, coupled with prolonged developmental durations and negatively affect reproductive activity.On the other hand, the antifungal effects of the same extract and its formulation were evaluated on Fusarium.oxysporum, Fusarium solani and Alternaria solani in vitro.Flavonoid extract (a.i) or formulation (SL) caused a decrease in the straight development of all fungi and had an inhibitory impact on the linear growth of fungal mycelial at all tested concentrations.The results showed that, the formulation (SL) is more effective than flavonoid extract (a.i).Flavonoid formulation (SL) gave completely inhibition for F. oxysporium at concentration of 8000 ppm, the EC50 value was 1860.90 ppm.Finally from this study and the previous results flavonoid extract formulation (SL) could be used as safe alternative of chemical pesticides against S. littoralis and F. oxysporum, F. solani and A. solani after complete the needed studies.