Trends in the selection of insecticide resistance in A nopheles gambiae s.l. mosquitoes in northwest T anzania during a community randomized trial of longlasting insecticidal nets and indoor residual spraying

• Published in: Medical and veterinary entomology Vol. 29; no. 1; pp. 51 - 59
• Main Authors: MATOWO, J., KITAU, J., KAAYA, R., KAVISHE, R., WRIGHT, A., KISINZA, W., KLEINSCHMIDT, I., MOSHA, F., ROWLAND, M., PROTOPOPOFF, N.
• Format: Journal Article
• Language: English
• Published: 01-03-2015
• ISSN: 0269-283X; 1365-2915
• DOI: 10.1111/mve.12090

Abstract
Anopheles gambiae s.l.
(
D
iptera:
C
ulicidae) in
M
uleba,
T
anzania has developed high levels of resistance to most insecticides currently advocated for malaria control. The
kdr
mutation has almost reached fixation in
A
n. gambiae s.s.
in
M
uleba. This change has the potential to jeopardize malaria control interventions carried out in the region. Trends in insecticide resistance were monitored in two intervention villages using
W
orld
H
ealth
O
rganization (
WHO
) susceptibility test kits. Additional mechanisms contributing to observed phenotypic resistance were investigated using
C
enters for
D
isease
C
ontrol (
CDC
) bottle bioassays with piperonylbutoxide (
PBO
) and
S,S,S
‐tributyl phosphorotrithioate (
DEF
) synergists. Resistance genotyping for
kdr
and
A
ce‐1
alleles was conducted using quantitative polymerase chain reaction (
qPCR
). In both study villages, high phenotypic resistance to several pyrethroids and
DDT
was observed, with mortality in the range of 12–23%. There was a sharp decrease in mortality in
A
n. gambiae s.l.
exposed to bendiocarb (carbamate) from 84% in
N
ovember 2011 to 31% in
D
ecember 2012 after two rounds of bendiocarb‐based indoor residual spraying (
IRS
).
A
nopheles gambiae s.l.
remained susceptible to pirimiphos‐methyl (organophosphate). Bendiocarb‐based
IRS
did not lead to the reversion of pyrethroid resistance. There was no evidence for selection for
A
ce‐1
resistance alleles. The need to investigate the operational impact of the observed resistance selection on the effectiveness of longlasting insecticidal nets and
IRS
for malaria control is urgent.