Options
A survey of the level of major enzymes involved in biochemical resistance of Aedes mosquitoes in Singapore
Author
Choong, Calvin Tsern Hoong
Supervisor
Lam-Phua, Sai Gek
Goh, Beverly P. L. (Beverly Pi Lee)
Abstract
Despite a well-established integrated nationwide Aedes mosquito control programme that incorporates chemical control, source reduction, public health education and law enforcement, Singapore has not been spared the regional resurgence of Dengue fever. The focus of this project was to establish biochemical baseline data of insecticide resistance of Aedes populations to pyrethroid and organophosphate in Singapore, by determining the activities of non-specific esterases, monooxygenases and acetylcholinesterases respectively. The mechanism underlying the insecticide resistance that involves the activities of non-specific esterases, monooxygenases and insensitive acetylcholinesterases was investigated. The feasibility of using a biochemical microassay, in term of enzyme activities as an early indicator of insecticide resistance was assessed. Field Aedes mosquitoes elicited little resistance and tolerance to organophoshorus compounds. High resistance to pyrethroid, observed as a high level of enzyme activities, was detected in field mosquitoes across Singapore. Resistance in field Aedes populations was mainly due to a metabolic process and to a lesser extent, a target site mutation. Results suggest that there is currently no cross resistance of the insecticides pyrethroid and organophosphate in field Aedes mosquitoes in Singapore. Enzyme microassays are feasible methods that can be applied in field insecticide resistance testing. Results of these assays can be used to guide decision-making on whether to embark on toxicity bioassays to save time and cost. This aids in better vector surveillance and management. They are also low cost, experimentally simple, rapid, reliable and sensitive at the level of individual insect. Surveillance and monitoring using these methods are highly recommended compared to lab-based toxicity bioassays.
Date Issued
2008
Call Number
QL536 Cho
Date Submitted
2008