BACKGROUND The massive use of
insecticides in
public health has exerted selective
pressure resulting in the development of resistance in
Aedes aegypti to different
insecticides in
Venezuela. Between 2010 and 2020, the only
insecticides available for
vector control were the
organophosphates (Ops)
fenitrothion and
temephos which were focally applied. OBJECTIVES To determine the
state of
insecticide resistance and to identify the possible biochemical and molecular mechanisms involved in three
populations of Ae. aegypti from
Venezuela.
METHODS CDC bottle
bioassays were conducted on Ae. aegypti collected between October 2019 and February 2020 in two hyperendemic localities for
dengue in Aragua
State and in a
malaria endemic area in Bolívar
State.
Insecticide resistance mechanisms were studied using biochemical assays and
polymerase chain reaction (
PCR) to detect kdr
mutations. FINDINGS
Bioassays showed contrasting results among
populations; Las Brisas was resistant to
malathion,
permethrin and deltamethrin, Urbanización 19 de Abril was resistant to
permethrin and Nacupay to
malathion. All
populations showed significantly higher activity of
mixed function oxidases and
glutathione-S-
transferases (GSTs) in comparison with the susceptible
strain. The kdr
mutations V410L, F1534C, and V1016I were detected in all
populations, with F1534C at higher frequencies. MAIN CONCLUSION
Insecticide resistance persists in three Ae. aegypti
populations from
Venezuela even in the relative absence of
insecticide application.