RESUMO
The content of the digestive tract of 4 authoctonous species of fishes that presented characteristics of larvivorous fishes was analyzed. It was found that 28% of the caught specimens of Aequidens pulcher presented in their gastrointestinal content residues of larvae and pupae of mosquitoes combined with other food, and that 26 5 has only larvae and pupae. In Aequidens coeruleopunctatus, 6 % of their content was larvae and pupae with other food, whereas 10% had only larvae and pupae. 56% of the Poecilia caucana specimens had larvae and pupae with other food, and 34% only larvae and pupae. Poecilia reticulata contained larvae and pupae with other food in 62% and 33% only had larvae and pupae. These results show an effective bioregulator activity in these fishes identified as larvivorous under natural conditions.
Assuntos
Ciclídeos/fisiologia , Controle de Mosquitos , Controle Biológico de Vetores , Poecilia/fisiologia , Animais , Comportamento Alimentar , Insetos Vetores , Larva , Pupa , VenezuelaRESUMO
Resistance of Culex quinquefasciatus from Miranda, Venezuela to the organophosphate insecticides malathion and chlorpirifos was higher than 30x whereas resistance to pyrethroids metylpirimifos, fention, cipametrine, deltametrine, permetrine and lambdacyalotrine and to organochlorate DDT was lower than 4x. Resistance mechanisms were analyzed with piperonyl butoxide synergist (multifunction oxidases) and S.S.S. phosphotrithiate tributyl (DEF, esterase inhibitor). Multifunction oxidases did not play a significant role in resistance to organophosphate insecticides and carbamate; however, esterases were only mechanisms of resistance to malathion and chlorpirifos. The only insecticide affected by DEF and PB was cipermetrine. Biochemical tests revealed a very low frequency of the altered acetylcholinesterase mechanism (0.13). Esterase frequencies were high (1). Electrophoresis exposed the B1, A6 and B6 esterase phenotypes.
Assuntos
Animais , Carbamatos , Culex , Inseticidas Organofosforados , Piretrinas , Acetilcolinesterase , Culex , Esterases , Genótipo , Oxirredutases , Resistência a Medicamentos , VenezuelaRESUMO
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.