The olfactory system of the head louse

BARROZO, ROMINA; ORTEGA INSAURRALDE, ISABEL; PICOLLO, MARÍA INÉS; TOLOZA, ARIEL CEFERINO

Workshop; Short Course in Insect Chemical Ecology; 2017

Pediculus humanus capitis is a cosmopolitan hematophagous insect that has parasitized humans since the beginning of humankind. Head louse has remarkable characteristics due to its high dependence on human hosts, thus affecting the behavior and physiology during food and refuge assessment. In contrast to body lice that are vector of deadly diseases to humans, head lice are not capable of spread disease, although their bites produce pruritus, excoriations and prolonged scratching can lead to bacterial infection. Recent studies on body lice and other related lice (i.e. pigeon lice) showed that their sensorial system is rather simple, though lice have a few sensilla in the antennae and mouthparts as well as the set of genes with presumed sensorial function. The constraints in the number of sensilla and chemosensory genes could be the result of its parasitic lifestyle.Our main goal was to have a better understanding on the process of how head lice choose a human host. In particular, we wanted to know whether head lice make host-selection decisions relying on olfactory information. Thus, this study undergoes different levels of analysis: from periphery to the central level. We also explored the morphology of the antennae and mouthparts of lice searching for putative olfactory sensilla. In addition, we analyzed the behavioral response of lice to human scalp odors. Finally, we started to describe the louse brain, and by means of antennal backfills we followed up the antennal projections to the brain.