Mi. Picollo et al., LABORATORY STUDIES OF SUSCEPTIBILITY AND RESISTANCE TO INSECTICIDES IN PEDICULUS-CAPITIS (ANOPLURA, PEDICULIDAE), Journal of medical entomology, 35(5), 1998, pp. 814-817
The susceptibility of local head lice to permethrin, sumithrin, deltam
ethrin, and carbaryl was determined by laboratory bioassays in field-c
ollected colonies. Head lice collected from the infested heads of chil
dren 6-12 yr old were tested within 3 h of collection. The longest sur
vival of control insects in the laboratory was obtained by keeping the
m in the dark at 18 degrees C and 70-80% RH. The base line susceptibil
ity data obtained for insects collected from children not treated for
lice, the reference colony, showed that deltamethrin caused the highes
t mortality of the insecticides tested (LC50, 0.06%). Permethrin, sumi
thrin, and carbaryl showed no significant difference in mortality (sup
erposition of confidence intervals), being 10 times lower than that ca
used by deltamethrin All field-collected lice required a higher LC50 o
f permethrin than the reference colony. Resistance levels varied from
3 to >100 for colonies that were taken from children treated with anti
-lice products. Lice colonies with permethrin resistance showed resist
ance to sumithrin and deltamethrin, but resistance was not observed to
the carbamate carbaryl.