Head lice are more attracted to blends of human scalp than to isolated compounds

V. ADJEMIAN; F. GALASSI; M. PICOLLO; P. GONZÁLEZ AUDINO

Buenos Aires

Congreso; 6T Congres of the Latin american assocition of chemical ecology; 2021

Pediculushumanus capitis (De Geer) is an obligate bloodsuckingectoparasite of human scalp. Pediculosis affects mainly kids at scholar age.Chemical cues areinvolved in the head lice - human interaction. These were recently analyzed byOrtega-Insaurralde et al. (2017) and Galassi et al. (2018, 2019). In the firstreport, authors demonstrated for the first time that adult head lice respondedto host chemical stimuli. They found that insects decreased their locomotoractivity and performed blood search associated behavior in presence of humanscalp samples. Later, Galassi et al. (2018) demonstrated that head lice werehighly attracted to volatiles present in human scalp, identified them and testedthe attraction towards the major individual components nonanal, sulcatone,geranyl-acetone and palmitic acid. More recently, these authors demonstratedthat head lice recognize and prefer the whole odor (highly and moderatelyvolatile emanations) of the human head over the whole odor of other parts ofthe human body. In this work, we studiedthe head louse attraction produced by the mixture of major volatiles from humanscalp extracts compared to their isolated components. So, we evaluated the headlouse attraction produced by human scalp main components alone and in mixtures.Although volatile fraction composition was already available from Galassi et al2018, we identified the whole odor (highly and moderately volatile emanations)composition in order to select major components for individual and in mixturesevaluation. We tried to establish if there are critical compounds involved inthe attraction behavior and if there is an optimal mixture involved attractionbehavior of lice towards the human host. Volatiles blends of nonanal, sulcatoneand geranylacetone presented a synergistic attractive effect (0,10>p-value>0,05)compared against isolated compounds. Whole odor tests are still in process.