Increased Mono-oxygenase Activity Associated with Resistance to Permethrin in Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae) from Argentina.

GONZÁLEZ AUDINO P., S. BARRIOS, C. VASSENA, G. MOUGABURE CUETO, E. ZERBA & M. I. PICOLLO

JOURNAL OF MEDICAL ENTOMOLOGY

Entomological Society of America.

Lugar: Lanham, Maryland; Año: 2006 vol. 42 p. 342 - 345

0022-2585

In this work we studied the profile of permethrin resistance in head lice populations infesting children aged 6-12 years old in schools and children homes from Buenos Aires and around (Argentina). Five permethrin resistant populations with different levels of resistance -Hogar Loyola (HL), Republica de Turquia (RT), Hogar Mitre (HM), Guardia de Honor (GH), Ricardo Guiraldes (RG)- and one susceptible population, Bandera Argentina (BA) were collected. The level of resistance was evaluated by the topical application method developed at CIPEIN. Results showed resistance ratios (RR) of 13 for HL, 16 for RT, 22 for HM, 61 for GH and 69 for RG. In order to elucidate the possible involvement of cytochrome P450 monooxygenase system in conferring permethrin resistance, ethoxycoumarin-O-deethylase (ECOD) activity was measured in abdomens of individual third nymphs and adults using a fluorometric assay.  The ECOD activity was lower in the susceptible BA population (4.7 ng/ins) than in the resistant ones (13.7 ng/ins for RG, 12.3 ng/ins for GH, 8.6 ng/ins for RT, 8.2 ng/ins for HL). The ECOD activity was significantly correlated to the level of resistance in the field populations (r= 0.97, p=0.0009) suggesting the role of cytochrome monooxygenase P450 system in permethrin resistance of P. humanus capitis.  Key words: Pediculus humanus capitis, monooxygenase, P450, permethrin resistance.