Banca de DEFESA: Kauara Brito Campos
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : Kauara Brito Campos
DATE: 15/06/2023
TIME: 08:30
LOCAL: Plataforma Teams
TITLE:
SUSCEPTIBILITY OF Ae. aegypti TO THE INSECTICIDES PYRIPROXYFEN AND MALATHION AND THE CAPACITY OF ZIKA VIRUS INFECTION IN POPULATIONS RESISTANT TO PYRIPROXYFEN
KEY WORDS:
Arbovirus, Aedes aegypti, insecticide resistance, organophosphate insecticides, pyriproxyfen, mosquito control, Zika virus, oral infection, vector competence
PAGES: 226
BIG AREA: Ciências da Saúde
AREA: Medicina
SUMMARY:
Introduction: Aedes aegypti chemical control in Brazil remains the main tool for preventing arboviral outbreaks. Monitoring the vector's susceptibility to insecticides is essential for replacing substances in case of confirmed resistance. Still, the relationship between resistant mosquitoes and the ability to infect arboviruses is little explored and unclear, especially with the Zika virus (ZKV). Objectives: To analyze the susceptibility of Ae. aegypti populations to the insecticides pyriproxyfen (PPF) and malathion between 2017 and 2018 in Brazil, as well as to reassess the evolution of PPF resistance after two years of exposure to bimonthly applications of the larvicide; and to investigate the relationship betweenresistant mosquitoes to PPF and its ability to be infected by ZIKV. Methods: Ae. aegypti eggs were collected in 132 cities using oviposition traps. Colonies were subjected to susceptibility tests with larvae exposed to the Diagnostic Dose (DD) of PPF (0.3 µg/L) and adults with the DD of malathion obtained in our laboratory (20 µg), in addition to the DD indicated by the World Health Organization (WHO) (50 µg) in bottle assay. Subsequently, DoseResponse (DR) bioassays with PPF were performed in populations with EI < 98% to estimate the RR. In 2020, eggs were collected in cities where we previously recorded PPF resistance for new DR bioassays. Mosquitoes from populations with different resistance levels to PPF and an insecticide-susceptible strain (Rockefeller) were experimentally orally infected with ZIKV to determine their relative vector competence. Results: Changes in susceptibility to PPF were recorded in 6 (4.5%) populations, in Bahia and Ceará states, with a Resistance Ratio (RR) from 1.51 to 3.58. For malathion, 73 (55.3%) of the populations distributed in the country were resistant when exposed to local DD (20 µg/bottle). On the other hand, no population was resistant, and only 10 (7.6%) populations showed reduced susceptibility (mortality rate 90 to 98%) when the WHO DD (50 µg/bottle) was used. In 2020, mosquitoes from Icó, Serrinha, and Brumado showed low levels of PPF resistance (RR50= 2.33, 4.52, and 4.83, respectively); moderate levels were detected in populations from Juazeiro do Norte (RR50=5.83) and Itabuna (RR50=7.88), and high level in Quixadá (RR50=11). Although all populations were competent to become infected with ZIKV, those with moderate to high levels of insecticide resistance (IR) exhibited similar or lower susceptibility to ZIKV infection compared to populations with low IR or the strain susceptible. Conclusions: Resistance to PPF was registered in Ae. aegypti populations from northeastern Brazil; as well as the local DD for malathion (20 µg/bottle) was more sensitive than the WHO one (50 µg/bottle) for early detection of decreased susceptibility; the evolution of this resistance can compromise efforts to control it, and continuous monitoring is essential for effective insecticide management. The use of PPF to control Ae. aegypti may be associated with the indirect benefit of reduced susceptibility to ZIKV infection without changes in disseminated infection and transmission of this arbovirus among PPF-resistant phenotypes.
BANKING MEMBERS:
Presidente - 1974062 - MARCOS TAKASHI OBARA
Interno - 3343228 - RODRIGO GURGEL GONCALVES
Externa à Instituição - DINAIR COUTO LIMA
Externa à Instituição - JULIANA TELLES DEUS - IP
Externa à Instituição - Grasielle Caldas DÁvila Pessoa