Response of Pediculus humanus capitis to Volatiles of Whole and Individual Components of the Human Scalp

A new study has evaluated the response of head lice to volatiles that emanate from the human scalp, identifying the volatile components of the odor and the attractive or repellent activity of their pure main components.

The study by Galassi et al., published in the January 2018 Journal of Medical Entomology identified twenty-four volatiles identified in the human scalp odor, with the main compounds being; nonanal, sulcatone, geranylacetone, and palmitic acid. These volatiles were collected by means of Solid Phase microextraction and the extract obtained was chemically analyzed by gas chromatograph-mass spectrometer.

The findings suggested that head lice were highly attracted by the blend human scalp volatiles, as well as by the individual major components. The results of this study indicate that head lice may use chemical signals in addition to other mechanisms to remain on the host.

A significant finding of this study was to demonstrate that nonanal activity depends on the mass of the compound as it is repellent at high concentrations and an attractant at low concentrations.