Head Lice Recognize and Prefer Head Odor Over Foot and Forearms.

F. GALASSI; M PICOLLO; P. GONZALEZ AUDINO

Buenos Aires

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

UBA

Human head lice Pediculus humanus capitis (De Geer) (Phthiraptera: Pediculidae) areinsect parasites closely associated with humans, feeding on the blood of their hosts andcausing them skin irritation and probable secondary infections. Despite being a severenuisance, very few studies have reported on intraspecifc chemical communication in headlice. Here, we evaluated the behavioral responses of head lice to the volatile compoundsand solvent extracts from their feces. We also chemically analysed the main volatilecomponents of these feces by CG-MS and those of the feces extracts by HPLC-MS. Headlice were attracted to the methanol extract of their feces but not to the hexane ordichloromethane extracts, suggesting the polar nature of bioactive chemicals present inhead louse feces. Follow-up chemical identifications, in fact, showed the presence ofhypoxanthine, uric acid, and another purine tentatively identified as either guanine or isoguanine. Additionally, head lice were significantly attracted by volatiles emitted fromsamples containing feces. The volatiles emanated from feces alone contained 19identified substances. The major compounds found were decanal, nonanal, hexanal, andacetic acid, together representing approximately 60% of the identified compounds. Thiswork represents the first chemical evidence of intraspecies communication among headlice. The results support the existence of active substances present in the feces of P.humanus capitis that may be involved in its aggregation behaviour.