Abstract

RODRIGUEZ, MARÍA M.; BISSET, JUAN; RODRIGUEZ, ILEANA  and  DIAZ, CRISTINA. Determinación de la resistencia a insecticidas y sus mecanismos bioquímicos en 2 cepas de Culex quinquefasciatus procedentes de Santiago de Cuba. Rev Cubana Med Trop [online]. 1997, vol.49, n.3, pp.209-214. ISSN 0375-0760.

It was analyzed the behavior of the resistance of 3 organophosphated insecticides (malathion, clorpirifos and methyl-pyrimifos), 3 pyrethroids (deltamethrin, lambda-cyhalothrin and cypermethrin), and 1 carbamate (propuxur) in populations of Culex quinquefasciatus from 2 municipalities of the province of Santiago de Cuba. The values of the resistance factor proved that there is resistance to malathion and clorpirifos. However, in spite of the existance of a high frequency of the mechanisms of elevated esterases and altered acetylcholinesterase no resistance to methyl-pymirifos, was observed which demostrated that this insecticide is not affected by these mechanisms selected in our populations of Culex quinquefasciatus. There was resistence to deltamethrin, and lambda-cyhalothrin in Santiago de Cuba, whereas it was moderate to cypermethrin in Santiago and San Luis. Resistance to delta-methrin was also found in San Luis, but it was mild to lambda-cyhalothrin. The results obtained from the use of the synergists S,S,S tributyl phosphotritiade (DBF) and piperonyl butoxide (PB) indicated that the mechanisms of resistance of unspecific esterases and oxidases of multiple function are involved in the resistance to pyrethroids in both strains from Santiago de Cuba and San Luis. It was determined by the biochemical tests that there existed a high frequency of the mechanisms of esterases and altered acetyl-cholinesterase. The results of the polyacrylamide gel electrophoresis (PAGE) showed that esterase B1 appears more frequently associated with esterases A6 and B6. It was inferred that this association coul be connected with the resistance to pyrethroids.

Keywords : INSECTICIDES, ORGANOPHOSPHATE [pharmacology]; CULEX [drug effects]; INSECTICIDE RESISTANCE [genetics]; MOSQUITO CONTROL [methods]; LARVA [enzymology]; LARVA [drug effects]; ESTERASES [genetics]; ACETYLCHOLINESTERASE [genetics].