Abstract

FIGUEROA ACOSTA, Luisa Elena; MARIN ALVAREZ, María; PEREZ PINTO, Enrique  and  MOLINA DE FERNANDEZ, Darjaniva. Mechanisms of resistance to organosyntetic insecticides in a population of Anopheles aquasalis Curry (Diptera: Culicidae) from Aragua State. Bol Mal Salud Amb [online]. 2006, vol.46, n.1, pp.39-47. ISSN 1690-4648.

Anopheles aquasalis from Aragua State is found in zones of developed agriculture and fishing near Valencia Lake and receives indirect pressure from the insecticides which are directed against agricultural pests. The level of resistance to the insecticides lambdacyhalothrin and pirimiphosmethyl was determined. Bioassays were carried out using the bottle method in which mosquitoes are exposed to glass bottles treated with insecticides, estimating as a threshold of resistance the survival of mosquitoes after 60-min exposure to a specific dose of the products evaluated. Mosquitoes turned out to be resistant to the pyrethroid lamdacyhalothrin at 0.1 μg/mL with TL98 at 140.7 min and to the organophosphate primiphosmethyl 0.1 μg mL with TL98 at 93.0 min. Resistance mechanisms were detected IN VIVO using the synergists piperonyl butoxide (PBO) and S, S, S, Trisbutylphosphotristioate and in IN VITRO using the substrate betanaphtylacetate. Multfunctional oxidases (MFO) and esterases are suggested as cause of resistance in these groups of insects. The values of the slope were between 3.7 and 7.6 which means that the population response was stable and homogenous. The results obtained contribute to a better knowledge of the insecticide resistance of this medically important species.

Keywords : pyrethroids; organophosphates; synergists; oxidases; esterases.