Insect growth regulatory effects by diterpenes from Calceolaria talcana Grau & Ehrhart (Calceolariaceae: Scrophulariaceae) against Spodoptera frugiperda and Drosophila melanogaster

► Pimaradiene and abietatriene from C. talcana showed insect growth inhibitory activity. ► The lethal concentration was between 20.0 and 30.0 μg/mL of compounds. ► Highest antifeedant inhibition was 100% at 20 μg/mL of cyclopropylpimaradiene. ► Cyclopropylpimaradiene and 2-hydroxynaphtoquinones were the majority active metabolites. ► At low concentrations were showed pre-emergence effects on S. frugiperda.