RESUMO
Vector control has been an essential strategy in Brazil to manage vector-borne diseases, and the use of insecticides plays an important role in this effort. Pyriproxyfen (PPF) has become a common insect growth regulator used to control juvenile stages of mosquitoes by disturbing their growth and development. This study assesses the susceptibility and resistance status of Brazilian Ae. aegypti populations that previously showed low resistance levels to PPF. Eggs of Ae. aegypti were collected from six cities located in the northeast states of Ceará (Quixadá, Icó, and Juazeiro do Norte), and Bahia (Itabuna, Brumado, and Serrinha). We used the Ae. aegypti Rockefeller strain as an experimental control and a strain known to be susceptible to insecticides. Inhibition of emergence rates by 50% of Ae. aegypti populations varied from 0.0098-0.046 µg/L. Mosquitoes from Icó, Serrinha, and Brumado showed low resistance levels [resistance ratio (RR50) = 2.33, 4.52, and 4.83, respectively], whereas moderate levels of resistance were detected in populations from Juazeiro do Norte (RR50=5.83) and Itabuna (RR50=7.88). Aedes aegypti collected from the Quixadá population showed a high resistance level to pyriproxyfen (RR50=11). The evolution of resistance in Brazilian Ae. aegypti populations to PPF can compromise vector control efforts. Continuous monitoring of insecticide resistance in Ae. aegypti is essential for making timely management decisions for effective vector control and management.
Assuntos
Aedes , Inseticidas , Piretrinas , Animais , Inseticidas/farmacologia , Resistência a Inseticidas , Brasil/epidemiologia , Hormônios Juvenis/farmacologia , Mosquitos Vetores , Piretrinas/farmacologiaRESUMO
Zika virus (ZIKV) infection has caused devastating consequences in Brazil as infections were associated with neurological complications in neonates. Aedes aegypti is the primary vector of ZIKV, and the evolution of insecticide resistance (IR) in this species can compromise control efforts. Although relative levels of phenotypic IR in mosquitoes can change considerably over time, its influence on vector competence for arboviruses is unclear. Pyriproxyfen (PPF)-resistant populations of Ae. aegypti were collected from five municipalities located in Northeast of Brazil, which demonstrated different resistance levels; low (Serrinha, Brumado), moderate (Juazeiro do Norte, Itabuna), and high (Quixadá). Experimental per os infection using ZIKV were performed with individuals from these populations and with an insecticide susceptible strain (Rockefeller) to determine their relative vector competence for ZIKV. Although all populations were competent to transmit ZIKV, mosquitoes derived from populations with moderate to high levels of IR exhibited similar or lower susceptibility to ZIKV infection than those from populations with low IR or the susceptible strain. These observations suggest an association between IR and arbovirus infection, which may be attributable to genetic hitchhiking. The use of PPF to control Brazilian Ae. aegypti may be associated with an indirect benefit of reduced susceptibility to infection, but no changes in disseminated infection and transmission of ZIKV among PPF-resistant phenotypes.