ABSTRACT
A study was conducted on the level of resistance to seven insecticides, namely, 3 organophosphate compounds (malathion, chlorpyrifos and pirimiphos-methyl), one carbamate (propoxur) and 1 pyrethroid (cypermethrin, deltamethrin and lambdacialotrine) of three field-collected strains of Blattella germanica (Linnaeus, 1767) from Santiago de Cuba. These strains showed high resistance levels to malathion, cypermethrin, deltamethrin and lambdacialotrine and low resistance to pirimiphos-methyl, and also they were susceptible to chlorpyrifos and propoxur. The levels of resistance to tested organophosphate insecticides such as malathion and pirimiphos-methyl and to pyrethroid compounds like cypermethrin, deltamethrin and lambdacialotrine may be related to the increased production of esterases as a mechanism of resistance. The value of frequency of the resistant genes for enzyme acetylcholinesterase was very low, therefore, the modified acetylcholinesterase is not involved in resistance to insecticides tested in the studied strains from Santiago de Cuba.
Subject(s)
Animals , Blattellidae , Insecticides , Insecticides, Organophosphate , Pyrethrins , Insecticide Resistance , Lethal Dose 50 , Models, Theoretical , PropoxurABSTRACT
As a result of the most recent dengue outbreak in Santiago de Cuba province, a strain of this vector was studied to determine the levels of sensitivity and/or resistance to organophosphate and pyrethoid insecticides. The results of bioassays showed low levels of resistance to fention, malathion and deltametrine, moderate levels of resistance to temephos, metyl-pirimifos and cipermetrine and high levels of resistance to chlorpirifios. According to the results obtained from the use of S.S.S. phosphotrithiate trybutil synergist, it was shown that esterases play an important role in resistance to temephos and chlorpirifos. Piperonyl butoxide synergist disclosed that multifunction oxidases were not involved in the resistance to any of the evaluated insecticides. Biochemical techniques were applied to detect esterase-, glutathione-S-transferase- and acetylcholineaterase-mediated resistance mechanisms of Aedes aegypti. In accordance with the high frequency values observed in each of the mechanisms, it was proved that esterases and glutathione-S-transferase were involved in the insecticide resistance but acetylcholinesterases were not. However, acetylcholinesterase gen was found in Aedes aegypti for the first time though at low frequency. The polyacrylamide-gel electrophoresis made it possible to observe a well-stained band with a relative mobility value of 0.779; this band was called A4 it was not observed in the reference strain and may be associated to organophosphate resistance which remains to be proved in future research.