[Status of insecticide susceptibility of public health use in natural populations of Aedes aegypti (Diptera: Culicidae) of Casanare, Colombia].

INTRODUCTION

Physiological resistance of Aedes aegypti is a major threat to effective control programs in the transmission of dengue virus.

OBJECTIVE

To determine the status of susceptibility to insecticides used in public health, in natural populations of A. aegypti from three endemic dengue localities of Casanare.

MATERIALS AND METHODS

Adult mosquitoes were recovered from A. aegypti immature stages from seven natural populations collected for three municipalities. The first filial generation was used to assess the biochemical mechanisms associated with loss of susceptibility: nonspecific esterase (NSE) and enzyme cytochrome P450 monooxygenases group. The second filial generation allowed us to evaluate the susceptibility to insecticides from bioassays using the CDC 1998 methodology for adult mosquitoes and WHO 1981 technique for larvae.

RESULTS

IN the seven adult populations recorded loss of susceptibility to organochlorine DDT and pyrethroids lambda-cyhalothrin and permethrin. Two populations showed susceptibility to deltamethrin and five populations showed susceptibility to cyfluthrin. There was a susceptibility to organophosphates temephos, malathion and fenitrothion in all populations. No population showed increased NSE but an increase of P450 in two populations

CONCLUSIONS

It appears that the P450 may play an important role in resistance to pyrethroids and DDT, still other resistance mechanisms may be acting in populations. Susceptibility to organophosphate allows continued use of this chemical group to interrupt transmission of dengue in Casanare.