UNIDEF   23986
UNIDAD DE INVESTIGACION Y DESARROLLO ESTRATEGICO PARA LA DEFENSA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Near fixation in knockdown resistance alleles to pyrethroids in head louse (Pediculus humanus capitis) populations from Argentina
Autor/es:
ARIEL C. TOLOZA; ASCUNCE MARINA; REED DAVID; MARIA INES PICOLLO
Reunión:
Conferencia; 5th International Conference on Phthiraptera; 2014
Resumen:
In Argentina, the overuse of products containing permethrin (a commonly
used synthetic pyrethroid) in the last three decades has led to the development
of resistant louse populations.
Pyrethroid insecticides act on the nervous system affecting
voltage-sensitive sodium channels (VSSC). Two point mutations at the
corresponding amino acid sequence positions T917I and L920F in the
voltage-gated sodium channel gene are mainly responsible for contributing to
knockdown resistance (kdr). The
management of pyrethroid resistance requires either early detection or the
characterization of the mechanisms involved in head louse populations that are
essential to perform optimal control strategies.
In the present study, we estimated the geographical distribution of kdr alleles in 154 head lice from six
geographic regions throughout Argentina. Pyrethroid resistance kdr alleles were found in high frequencies ranging from 67 to 100%,
reaching near fixation. Of these, 131 (85.1%) were homozygous resistant, 13
(8.4%) were homozygous susceptible, and 10 (6.5%) were heterozygous. Exact
tests for Hardy-Weinberg equilibrium for each location showed that genotype
frequencies differed significantly from expectation in 4 of the 6 sites studied
(67%). These results show that pyrethroid resistance is well established and
has evolved rapidly among head louse populations from Argentina.