Assessment of insecticide resistance of (Diptera: Culicidae) populations to insect growth regulator pyriproxyfen, in the northeast region of Brazil.

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 populations that previously showed low resistance levels to PPF. Eggs of 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 Rockefeller strain as an experimental control and a strain known to be susceptible to insecticides. Inhibition of emergence rates by 50% of populations varied from 0.0098-0.046 µg/L. Mosquitoes from Icó, Serrinha, and Brumado showed low resistance levels [resistance ratio (RR) = 2.33, 4.52, and 4.83, respectively], whereas moderate levels of resistance were detected in populations from Juazeiro do Norte (RR=5.83) and Itabuna (RR=7.88). collected from the Quixadá population showed a high resistance level to pyriproxyfen (RR=11). The evolution of resistance in Brazilian populations to PPF can compromise vector control efforts. Continuous monitoring of insecticide resistance in is essential for making timely management decisions for effective vector control and management.