Chemical constituents of essential oils of Muna, Bolivian plants traditionally used as pesticides, and their insecticidal properties against Chagas' disease vectors

The composition of essential oils from two muna, Bolivian medicinal plants, derived from Minthostachys andina and Hedomea mandonianum, were analyzed by gas chromatography/mass spectrometry. Major differences were observed in their chemical composition. Pulegone was the major component of H. mandonianum oil (44.6%) and M. andina oil (25.5%); menthone and isomenthone were around 33% of these oils. Differences were also observed in their insecticidal activity against the Chagas' disease vector, Rhodnius neglectus or Triatoma infestans bugs exposed on impregnated oil filter papers. While M. andina oil showed 30%-50% of mortality in both triatomine species after a period of 1 week, H. mandonianum oil did not show any insecticidal activity. Nevertheless, both species had insecticidal activity (33.3% and 50%) when oils were topically applied. The significance of these results is discussed in relation to the variability of the chemical composition and their potential use in Chasgas' disease vector control.