A differential response to essential oil vapors of Pediculus humanus capitis and Pediculus humanus humanus (Anoplura: Pediculidae).

ARIEL C. TOLOZA1, GASTÓN MOUGABURE CUETO1, J. ZYGADLO2, EDUARDO N. ZERBA1 & MARÍA I. PICOLLO1

Buenos Aires

Congreso; International Congress on Phthiraptera; 2006

CIPEIN

The head and body louse are conspecific and are obligate human ectoparasites that differ on their preferred location on the host. It has been suggested that both posses similar toxicological response and either head or body lice could be employed in laboratory assays. In recent years, the use of essential oils for pest control has received great interest because of their lower mammalian toxicity and low persistence in the environment. The purpose of the present study was to evaluate the vapor activity of three Eucalyptus essential oils compared to the synthetic insecticide DDVP against field permethrin-resistant head lice from Buenos Aires and a laboratory body lice strain. Head lice were collected from heads of infested children 6-12 yr old, using a fine toothed antilouse comb. Fumigant activity was evaluated in an enclosed chamber that allowed to create a vapor system. Control consisted of the enclosed chamber without the addition of any substance. The number of knockdown head and body lice was recorded every 5 min for 1h, and then a Probit regression analysis was made to determine the knockdown time 50% (KT50) of the tested components. There was a significant differential response between head and body lice to the evaluated essential oils. Head lice were more susceptible to the vapors of Eucalyptus viminalis, Eucalyptus saligna and Eucalyptus cinerea than body lice; with KT50 values of 18.16, 16.04 and 19.25 min, respectively. However, no significant toxicological difference was found when head and body lice were exposed to vapors of DDVP, with KT50 values of 21.99 and 31.51, respectively. The differential toxicological susceptibility of head and body lice related with permethrin resistance is discussed.