Insecticidal efficacy of the essential oil of jambú (Acmella oleracea (L.) R.K. Jansen) cultivated in central Italy against filariasis mosquito vectors, houseflies and moth pests

Ethnopharmacological relevance Acmella oleracea (L.) R.K. Jansen (Compositae), well-known as jambú, is a medicinal herb of pungent taste, native to Brazil but cultivated in different parts of the world due to its aromatic and pharmacological properties. In folk medicine, the plant has been used against parasites and to combat insects and mites. No data are available on the insecticidal activity of jambú essential oil. Aim of the study To test the jambú essential oil obtained from A. oleracea cultivated in central Italy against the filariasis vector, Culex quinquefasciatus, the Egyptian cotton worm, Spodoptera littoralis, and the housefly, Musca domestica. Materials and methods The chemical composition of the essential oil was achieved by GC-FID and GC-MS analyses. Acute toxicity experiments were conducted on larvae of the filariasis vector C. quinquefasciatus and S. littoralis and adults of M. domestica to determine the LC50(LD50) and LC90(LD90) values of the oil, along with the positive control, α-cypermethrin. Results (E)-caryophyllene (20.8%), β-pinene (17.3%), myrcene (17.1%) and caryophyllene oxide (10.0%) were the major volatile constituents. Interestingly, the oil contained little amounts (3.9%) of the insecticidal spilanthol. Jambú essential oil exerted relevant effects on C. quinquefasciatus (LC50 = 42.2 mg L−1, LC90 = 73.6 mg L−1) and S. littoralis 3rd instar larvae (LD50 = 68.1 µg larva-1, LD90 = 132.1 µg larva-1). High acute toxicity was also detected testing the jambú oil against adult females of M. domestica, achieving a LD50 value of 44.3 µg adult-1 and a LD90 value of 87.5 µg adult-1. Conclusions Taken together our data support the traditional use of jambú as an insecticidal agent and represent the scientific basis for the industrial exploitation of the essential oil in the fabrication of green insecticides.