FUMIGANT BIOACTIVITY OF ESSENTIAL OILS FROM NATIVE ARGENTINEAN PLANTS AGAINST HEAD LICE PEDICULUS HUMANUS CAPITIS (ANOPLURA: PEDICULIDAE)

TOLOZA. A.C.; MOUGABURE CUETO G. A.; ZYGADLO J.; ZERBA E. AND PICOLLO M.I.

Montevideo, Uruguay.

Congreso; V Reunión de la Sociedad Latinoamericana de Fotoquímica “Prof. Emer. Patrick Moyna”. I Congreso de Fitoterápicos del Mercosur.; 2005

Parasitic diseases represent a serious health problem in most of the countries. In particular, the infestation with head lice (Pediculus humanus capitis) or pediculosis, represents a widespread problem affecting most of the primary school children. The strategies developed for the chemical control of  head lice have been based in a wide variety of insecticides such as DDT, lindane, carbaryl, malathion and pyrethroids. Despite the insecticides employed, their repeated use have resulted in the development of resistance to one or more of this products in several countries during the past decades (1). Thus, one alternative to conventional insecticides is the new use of botanical compounds such as essential oils (EO), which have evoked a great deal of interest as a natural means of pest control because of its repellent, ovicidal, adulticidal, feeding inhibition and attractant activity against various insect species (2). The purpose of the present study was to evaluate the vapor activity of essential oils of native plants from different regions of Argentina against permethrin-resistant head lice from Buenos Aires. The native plants Acantholippia riojana, Aloysia polystachia, Artemisia verlotorum, Chenopodium ambrosioides, Minthostachys verticillata, Myrcianthes cisplatensis, Psila spartioides and Schinus areira were collected in the spring season of 2003 and 2004 from different regions of Argentina. Dried leaves of each individual plant species were hydrodistilled in Clevenger-like apparatus by 1 h and the obtained oils were dried over anhydrous sulphate and stored in a refrigerator until analysis. Fumigant activity of the tested substances was evaluated in an enclosed chamber (70cm3) that allowed to create a vapor system. A total of 60 mL of the tested EO was used in each treatment. Control consisted of the enclosed chamber without the addition of any substance. The number of knockdown head lice was recorded at fixed time intervals of 5 min for 1h, and then a probit regression analysis was made to determine the knockdown time 50% (KT50 ) of the tested substances. The most effective vapors of the EO were those belonging to Myrcianthes cisplatensis, Aloysia polystachia, Minthostachys verticillata and Schinus areira, with KT50 values of 1.29, 23.43, 39.36 and 40.40 min, respectively. The potential of the essential oils for the control of permethrin-resistant Pediculus humanus capitis is discussed.