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

• Published in: Industrial crops and products 2013-02, Vol.45, p.283-292
• Main Authors: Muñoz, Evelyn, Escalona, Daniela, Salazar, Juan R., Alarcon, Julio, Céspedes, Carlos L.
• Format: Article
• Language: English
• Subjects: Abietatriene; aerial parts; Bioinsecticides; Calceolaria; Calceolaria talcana; Calceolariaceae; corn; diet; Diptera; Diterpenes; diterpenoids; Drosophila melanogaster; Drosophilidae; fruit flies; fruits; insect growth; Insect pests; Insect-growth-regulation; insecticidal properties; Lepidoptera; metabolism; naphthoquinones; Noctuidae; Pimaradiene; Scrophulariaceae; Spodoptera frugiperda; triterpenoids
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2012.12.038

► Pimaradiene and abietatriene from C. talcana showed insect growth inhibitory activity. ► The lethal concentration was between 20.0 and 30.0μg/mL of compounds. ► Highest antifeedant inhibition was 100% at 20μg/mL of cyclopropylpimaradiene. ► Cyclopropylpimaradiene and 2-hydroxynaphtoquinones were the majority active metabolites. ► At low concentrations were showed pre-emergence effects on S. frugiperda. The n-hexane extract from aerial parts of Calceolaria talcana (Calceolariaceae, formerly Scrophulariaceae) afforded 1,10-α-cyclopropyl-4,13-dimethyl-19-α-hydroxy-9-epi-ent-7,15-isopimaradiene (1,10-cyclopropyl-9-epi-ent-isopimarol) 1, and 19α-hydroxy-8,11,13-abietatriene 2 together with other known triterpenes and naphthoquinones. These natural products together with n-hexane extract and several fractions showed insecticidal and insect growth regulatory activity against fall armyworm (Spodoptera frugiperda, Lepidoptera: Noctuidae), and fruit fly (Drosophila melanogaster, Diptera: Drosophilidae), insect pests of corn and fruits, respectively. The most active samples were a mixture (M1) of the diterpenes 1+2 (6:4) that showed insecticidal activity between 10 and 20ppm. Additionally, a mixture of triterpenes 3–5 (M2), fraction 5 (F-5), a mixture of two naphthoquinones 6, 7 (M3), and the n-hexane extract, which had significant effects between 20.0 and 35.0μg/mL in diets. Almost all samples were insecticidal with lethal doses between 35 and 50μg/mL. Our results indicate that these compounds at low concentrations appear to have selective effects on the pre-emergence metabolism of the insect. The results were fully comparable to known natural insect growth inhibitors such as gedunin, MeOH-Cedrela and MeOH-Yucca extracts, suggesting a possible role as natural insecticidal agents.