ARRESTANT EFFECT OF HUMAN SCALP COMPOUNDS ON PEDICULUS HUMANUS CAPITIS BEHAVIOUR

ISABEL ORTEGA INSAURRALDE; ARIEL CEFERINO TOLOZA; PAOLA GONZALEZ AUDINO; MARÍA INÉS PICOLLO

Congreso; 1st Joint meeting ISCE/ALAEC; 2016

International Society of chemical ecology

The human headlouse, Pediculus humanus capitis (Phthiraptera: Pediculidae), is anobligate ectoparasite that causes Pediculosis capitis and has been incontact with humans since the beginning of humankind. Head lice depend exclusively on the human scalp microenvironmentwhich provides them with refuge, food and oviposition sites during their entirelife cycle. Unfortunately, there is no information about the chemicalcommunication that occurs when a louse interacts with its host.  Host related cues have been widely shown to inducestereotyped behaviour in the parasites and epidemiological reports indicate the presence of differential levels ofinfestation among humans. Considering it, we proposed the hypothesis that humanscalp compounds could modify the behaviour of head lice.In this work, we studied the effect of human scalpcompounds on the behaviour of adult head lice. Filter paper segments  were rubbed on volunteers scalps during 30seconds and then were placed in the test arena. The movement of the insects wasrecorded using the software EthoVision®. Average movement parameters werecalculated for the treatments in the bioassays such as total distance,velocity, frequency in the zone transition and time in each zone of the arena. We found that scalpcompounds induced head lice to decrease average locomotor activity and toremain arrested on the treated paper. We also observed that head lice, incloseness with human scalp substances, performed behaviour presumablyassociated to the search for blood on the skin such as stillness, body raisingperpendicular to the surface, and head disposition near  the surface.  Ourresults showed for the first time the effect of host compounds conditioning headlice behaviour. We discuss the role of these compounds in the dynamics of  head lice infestation.