Insecticidal activity of chicory (Cichorium intybus L.) extracts against two dipterous insect-disease vectors: Mosquito and housefly

Abstract

The plant chicory, Cichorium intybus L. (Asteraceae), was subjected to a bioassay-guided fractionation scheme, starting with successive extraction of the whole plant powder with petroleum ether, chloroform, ethyl acetate and methanol. Toxicity screening against larvae and adults of the mosquito (Anopheles pharoensis) and the housefly (Musca domestica), revealed high potency for petroleum ether and chloroform extracts, with LC50 of 15.3mgkg−1 and 0.023mg/cm2 against larvae and adults of mosquitoes, respectively. The LC50 for housefly larvae equaled 65.8mgkg−1 and the LD50 for adults equaled 0.112μg/insect. Saponification of petroleum ether extract resulted in saponifiable and unsaponifiable fractions, the latter was highly toxic than the former. Their activity was referred to the presence of fatty acid methyl esters in the saponifiable fraction, and sterols and hydrocarbons in the unsaponifiable fraction. Successive TLC fractionation to the chloroformic extract resulted in isolation and identification of two biologically active compounds, e.g., lactucopicrin-15-oxalate (compound I) and chicoralexin (compound II); both showed high toxicity towards the two tested insects. Compound II was more toxic than compound I to the mosquito larvae, while the opposite was obtained for the housefly larvae. The two compounds possessed equitoxic values against the adult stages of both insects. It was concluded that fractionation of the chicory plant (C. intybus) was in favor of toxicity increase towards the two insect pests used in the present study. Moreover, the obtained results provide new data on the insecticidal efficacy of this native plant against pests of medical importance such as mosquitoes and housefly.