Synergistic interaction of thymol with Piper ribesioides (Piperales: Piperaceae) extracts and isolated active compounds for enhanced insecticidal activity against Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract Background Plant secondary metabolites or mixtures in extracts essential oils are well known to enhance the activity binary mixtures. The present study is first report that thymol synergistically additively enhances of P. ribesioides and isolated compounds against S. exigua larvae at sublethal doses. Results Thymol was synergistic when mixed with hexane extract; however, if extract level higher (LD 30 ) than 10 ), reaction antagonistic. CH 2 Cl were more toxic alone, EtOAc synergized by components combined similar levels (1:1 thymol:EtOAc LD ). MeOH individually had moderate insecticidal activity, but all combinations as Isolated compounds, piperine, phenethyl cinnamamide cinnamic acid represented synergistic, additive, antagonistic action after combining Detoxification enzymes exposure insects treatments showed + could inhibit CE, GST AChE exceptional being piperine thymol, which induced detoxification enzyme activity. Conclusion extract- dose-specific. impact on variable dependent composition doses used a mixture. In this metabolic model, major insect compound an may become detoxified, whereas minor will act unimpeded, showing lower 50 acting alone. This model suggests synergizes differently, depend specific dose applied. Such studies help design effective insecticides based natural plant compound. Graphical abstract