Bioassay and biochemical studies of the status of pirimiphos-methyl and cypermethrin resistance in Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Singapore Singapore 138667
- Author:
Lee, R.M.L.
;
Choong, C.T.H.
;
Goh, B.P.L.
;
Ng, L.C.
;
Lam-Phua, S.G.
- Publication Type:Journal Article
- From:Tropical Biomedicine
2014;31(4):670-679
- CountryMalaysia
- Language:English
-
Abstract:
Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stegomyia) albopictus (Skuse)
were sampled from five regions of Singapore (Central, North East, North West, South East and
South West) and tested with diagnostic concentrations of the technical grade insecticides,
pirimiphos-methyl and cypermethrin. Biochemical assays were performed on the same
populations of Ae. aegypti and Ae. albopictus to determine activities of detoxifying enzymes,
including non-specific esterase (EST), monooxygenase (MFO) and acetylcholinesterase
(AChE). The diagnostic test showed that all Ae. aegypti populations were susceptible to
pirimiphos-methyl (mortality = 99 to 100%), but resistant to cypermethrin (mortality = 11 to
76%). Resistance to pirimiphos-methyl was observed in all Ae. albopictus populations (mortality
= 49 to 74%) while cypermethrin resistance was detected in most Ae. albopictus populations
(mortality = 40 to 75%), except those from Central (mortality = 86%) and South East (mortality
= 94%) showing incipient resistance. The biochemical assays showed that there was significant
enhancement (P < 0.001) of MFO activity in pyrethroid-resistant Ae. albopictus populations
and most Ae. aegypti populations. The biochemical assay results suggested that AChE could
play a role in pirimiphos-methyl resistance of Ae. albopictus in South West, South East and
North East regions. The small but significant increase in EST activities in Ae. aegypti from all
regions suggest that it may play a role in the observed cypermethrin resistance.
- Full text:W020150601560672028939.pdf
