[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. The larvae proved to be susceptible to clorpirifos, malathion and methylpyrimifos. The results obtained through the use of sinergists indicated that esterases play an important role in the detected resistance to organophosphate insecticides, but not in the resistance to propoxur. However, the monooxigenases take part only in the resistance to fenitothrion. These mechanisms were found at an elevated frequency in the larvae from this municipality. It was confirmed the role played by esterases in the resistance to temephos by polyacrilamide gel inhibition tests.