Levels of insecticide resistance and resistance mechanisms in Aedes aegypti from some Latin American countries.

Eight Latin American strains of Aedes aegypti were evaluated for resistance to 6 organophosphates (temephos, malathion, fenthion, pirimiphos-methyl, fenitrothion, and chlorpirifos) and 4 pyrethroids (deltamethrin, lambdacyhalothrin, betacypermethrin, and cyfluthrin) under laboratory conditions. In larval bioassays, temephos resistance was high (resistance ratio [RR50], > or =10X) in the majority of the strains, except for the Nicaragua and Venezuela strains, which showed moderate resistance (RR50, between 5 and 10X). The majority of the strains were susceptible to malathion, fenthion, and fenitrothion.

[Determination in vivo of the role of esterase and glutathione transferase enzymes in pyrethroid resistance of Aedes aegypti (Diptera: Culicidae)].

An in vivo study of two synergists, that is, Triphenil phosphate -specific esterase inhibitor- and ethacrynic acid -specific gluthation transferase inhibitor- was performed to determine if these enzymes were responsible for pyrethroid resistance of Aedes aegypti. To this end, two insecticide resistant Aedes aegypti strains were used, one strain selected with temephos by six selection generations (SAN-F6) and the other strain with delmamethrin by 12 selection generations (SAN-F12), being both strains resistant to pyrethroid insecticices. Through the use of TPP and EA synergists, it was proved that esterase and gluthation-s-transferase (GST) enzymes were responsible for pryrethroid resistance of these strains.

[Insecticide resistance mechanisms of Aedes aegypti (Diptera: Culicidae) from two Peruvian provinces].

Insecticide resistance of Aedes aegypti larvae and adults from two Peruvian provinces, that is, Trujillo and Tumbes provinces, was conducted. High infestation indexes and extensive use of insecticides based on the Vector Surveillance and Control Strategy of the Ministry of Public Health prevailed in these places. Larval bioassays revealed susceptibility to organophosphorate insecticide called malathion in TRUJILLO strain, it being moderate to fention and fenitrotion and high to chlorpyriphos and temephos;however, TUMBES strain was susceptible to the evaluated organophosphorate compounds, except for fention, with moderate resistance.

Selection of insensitive acetylcholinesterase as a resistance mechanism in Aedes aegypti (Diptera: Culicidae) from Santiago de Cuba.

A sample of Aedes aegypti (L.) (Diptera: Culicidae) from Santiago de Cuba, Cuba, with a high level of propoxur resistance compared with the reference susceptible Rockefeller strain (12.60 x at the 50% lethal concentration [LC50] and 18.

[Status of resistance to insecticides and resistance mechanisms in larvae from Playa municipality collected during the intensive campaign against Aedes aegypti in Havana City, 2001-2002].

The levels of susceptibility and/or resistance to inseciticides in Aedes aegypti larvae collected at the municipality of Playa during the intensive campaign against the mosquito Aedes aegypti, in Havana City, in the present year, were determined. In larvae, it was found a high resistance to the organophosphate insecticides phention and temephos and moderate to fenitrothion. A high resistance to propoxur carbamate was also detected.

[Resistance to insecticides in larvae and adults of Aedes aegypti, Havana City: prevalence of A4 esterasa associated with resistance to temephos].

2 strains of Aedes aegypti from 2 people's councils with high indexes of infestation of this vector were studied due to the need of carrying out an effective control of larvae and adults in the municipality of Guanabacoa. The levels of susceptibility and/or resistance to organophosphate insecticides, pyrethroids and a carbamate were determined. The results of the bioassays in larvae showed a complete susceptibility to organophosphate insecticides, malathion, clorpirifos, methyl-pyrimifos and propoxur carbamate in both people's councils.