Protectant potential of Marigold oil (Tagetes erecta L.) and its fractions against Tribolium castaneum (Herbst)

The essential oil from fresh flowers of Tagetes erecta was extracted by steam distillation using Dean and Stark apparatus. Refractive index, optical rotation, acid value, pH value and specific gravity of the oil were determined. Thin layer and column chromatography of oil was carried out to obtain the non-polar and polar fractions. Flower oil was found to be highly effective as insecticide where complete mortality of T. castaneum was achieved in 7 days at 5000 μg ml⁻¹. Among the various fractions, non-polar fraction had the highest potential as insecticide where complete mortality was observed in 4 days at 4000 μg ml⁻¹ concentration. The bioefficacy of the oil as well as the fraction was found to be dose and time dependent.