Perfil de susceptibilidad a Temefos en poblaciones de Aedes aegypti (Diptera: Culicidae) de Ciudad del Este - Alto Paraná, Paraguay

In Paraguay, the control of Aedes aegypti mosquitoes, involved in the transmission of several arboviruses, implies the use of temephos, an organophosphate that has been used by national vector control programs for more than two decades in search of reducing larval stages. In view of the need to evaluate periodically the larvicidal activity of this chemical compound, this study aimed to monitor the susceptibility profile to temephos of larval stages of Ae. aegypti. For this, an experimental analytical study with bioassays dose rate – response was applied, using third instar larvae of the first generation from a mosquitoes colony collected in Ciudad del Este. The larvae were exposed to different concentrations ranges of themephos that were defined by a pre-test. The number of larvae exposed and mortality at the end of each trial were recorded. The results determined the LC50 = 0.00966 mg/L and LC90 = 0.03015 mg/L, from which quantitative indicators of resistance were obtained, resistance ratio RR = 2.3734 and 4.1643 respectively. The latter value indicates characteristics related to low resistance in populations of Ae. aegypti evaluated according to standardized ranges (RR> 3 <5). The results observed in larval wild populations indicate an alert situation, considering that our study showed an incipient process of resistance to temephos. Finally, based on these results, proposing and implementing strategies based in actions that allow to preserve the larvicidal activity of this compound are recommended to avoiding the progressive increase of resistance in wild populations.