COMPARATIVE SUSCEPTIBILITY OF LARVAE OF 3 AEDES SPECIES TO MALATHION AND PERMETHRIN

Larvae of Aedes hendersoni, Ae. atropalpus, and 6 geographic strains o f Ae. triseriatus were compared in terms of their susceptibility to ma lathion and permethrin. Aedes atropalpus was most tolerant to malathio n, whereas Ae. triseriatus (Walton strain) was most tolerant to permet hrin. Malathion LC(50)s for 6 geographic strains of Ae. triseriatus ra nked from high to low were: Alabama (ALA) > Michigan (UNDERC)> Indiana (WAL)> Kentucky (UKEN) > Texas (SAL)> Florida (VB); similar ranking o f permethrin LC(50)s resulted in: WAL > VB > SAL > UKEN > UNDERC > ALA . Differences in susceptibility were detected but were not considered large (i.e., over several orders of magnitude). As a result, no change in application rate of malathion or permethrin, from an operational v iewpoint, would be warranted if used against these 3 mosquito species or the geographic strains of Ae. triseriatus investigated.