Insect growth regulatory activity of some extracts and compounds from Parthenium argentatum on fall armyworm Spodoptera frugiperda

The methanolic extract from aerial parts of Parthenium augentatum. afforded argentatin A and B. These compounds were evaluated for their effect on the fall armyworm (Spodoptera frugiperda). Toosendanin. a commercial insectici de derived from Melia azedarach was used as positive control. When tested f or activity, using neonate larvae into the no-choice artificial diet bioass ays, argentatin A, argentatin B and methanol extract caused significant gro wth inhibitory activity with GC(50) of 17.8. 36.1 and 6.4 ppm at 7 days. re spectively, and increased the development time of surviving larvae in a con centration-dependent manner with RGI values of 0.40, 0.60 and 0.26. at 25.0 , 25.0 and 5.0 ppm, respectively. In addition, it was possible to observe i n most of the treated groups a significant delay in the time of pupation, a dult emergence and deformities. Acute toxicity against adults of S. frugipe rda was also found. MeOH extract had the most potent activity with LDS, val ue of 3.10 ppm. In addition, MeOH extract and argentatin A caused acetylcho linesterase inhibition of 93.7% and 90.0%. at 5.0 and 50.0 ppm, respectivel y: whereas argentatin B had only slight inhibitory activity Therefore, the MeOH extract was identified as insecticidal extract from P. argentatum with activity at concentrations above 15.0 ppm.