Insecticidal activity of the essential oil and extracts of Gutierrezia mandonii and G. repens (Asteraceae) growing in Argentina

The insecticidal activities of essential oils (EO), the remaining water phase (RW) from the hydrodistillation, and the dichloromethane and methanolic extracts from Gutierrezia repens Griseb. and Gutierrezia mandonii (Sell. Bip.) Solbrig were evaluated. The GC and GUMS analyses of the oils resulted in the identification of 52 compounds from G. mandonii and 17 compounds from G. repens comprising 88.7% and 98.5% of the oils, respectively. Sabinene (0-13.1%), beta-pinene (6.4-17.8%) limonene (0.7-13.3%), (E)-beta-ocimene (1.3-7.0%), terpinen-4-ol (0.7-4.1%), spathulenol (0-4.1%) and, the isomers (6R,7R)-bisabolone (6.6-58.0%) and (6S,7R)-bisabolone (0-1.6%) were the main components of the oils. Mortality and development delays of Ceratitis capitata larvae, reared using a treated artificial diet, were recorded. Gutierrezia mandonii methanolic extracts and the oil produced lethal effects (p <= 0.05). Methanolic and dichloromethane extracts, the oil and the remaining water from distillation (RW) produced sublethal effects. Meanwhile dichloromethane and methanolic extracts, the oil and RW from G. repens resulted in significant mortality (p <= 0.05), and all causing also significant development delays. The required concentration of G. repens oil to avoid development in 50% of C. capitata larvae (EC50) was significantly lower than G. mandonii.