A Culex quinquefasciatus Say 1823 strain with resistant
genes to organophosphates was tested in the laboratory to
know the reproductive potential after exposure, as larvae,
at the LC^30 and LC^70 (mg/l) of three organophosphorus
insecticides: malathion, chlorpyrifos and
methyl-pirimiphos. Data showed that fecundity was decreased
significantly by malathion at LC^30=0.0025 and LC^70=
0.0075, whereas fertility had a no significant decrement by
chlorpyrifos and methyl-pirimiphos at the LC^70 (0.000016,
0.00043). The sexual index was affected by chlorpyrifos and
methyl-piritniphos showing a greater number of adult
females.