In Brazil, decades of
dengue vector control using
organophosphates and
pyrethroids have led to dissemination of resistance. Although these
insecticides have been employed for decades against Aedes aegypti in the country, knowledge of the impact of
temephos resistance on vector viability is limited. We evaluated several fitness parameters in two Brazilian Ae. aegypti populations, both classified as
deltamethrin resistant but with distinct resistant ratios (RR) for
temephos. The
insecticide-susceptible Rockefeller strain was used as an experimental control. The population presenting the higher
temephos resistance level, Aparecida de Goiânia, state of Goiás (RR(95) of 19.2), exhibited deficiency in the following four parameters: blood meal acceptance, amount of ingested blood, number of eggs and frequency of inseminated females. Mosquitoes from Boa Vista, state of Roraima, the population with lower
temephos resistance level (RR(95) of 7.4), presented impairment in only two parameters, blood meal acceptance and frequency of inseminated females. These results indicate that the overall fitness handicap was proportional to
temephos resistance levels. However, it is unlikely that these disabilities can be attributed solely to
temephos resistance, since both populations are also resistant to
deltamethrin and harbour the kdr allele, which indicates resistance to
pyrethroids. The effects of reduced fitness in resistant populations are discussed.