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Dengue vector control in Sri Lanka: Occurrence of `kdr’ type mutations and wolbachia in Aedes vector mosquito populations, and the effect of insecticide fogging on insect pollinators.

NRC Grant:  14-094

Prof. S.H.P.P. Karunaratne
Dept. of Zoology
Faculty of Science
University of Peradeniya
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Area of Research:Genetics & Medical Science
Status:Ongoing

 

objectives

a) To determine the presence and prevalence of different `kdr’ types mutations in the voltage gated sodium channel regulatory genes which are responsible for Aedes aegypti and Aedes albopictus resistance to pyrethroids through target site insensitivity.

b) To assess the effect of pyrethroid fogging on non-target insects, especially pollinators.

c) To determine the presence and prevalence of Wolbacia in Aedes aegypti and Aedes albopictus populations.

overview

Aedes aegypti and Ae. albopictus are the major vectors of dengue.  Dengue disease control of the island is mainly achieved through vector control by elimination of breeding sites and application of insecticides.  Insecticide fogging has been widely used for several years in Sri Lanka to control dengue vectors, especially during disease outbreaks. Development of pyrethroid resistance can hamper dengue control programmes and early detection of resistance and the underlying molecular mechanisms is of vital to the success of dengue control in the country.  Gene mutations (known as kdr type mutations) in the pyrethroid target site `sodium channel regulatory proteins of the insect nerve membrane’ bring about insensitivity to pyrethroids.  To date, more than thirty seven such mutations have been detected in these target sites and eight are from Ae. aegypti and Ae. albopictus.  The proposed study will explore the presence of kdr type mutations in dengue vector populations for the first time in Sri Lanka.  Such knowledge would help to decrease dengue incidence and also will prolong the effectiveness of available insecticides.  During this project, effect of insecticide fogging on insect pollinators and thereby to the ecosystems and to the economy of the country will be assessed systematically.  With increasing resistance to insecticides in mosquito populations and environmental concerns for insecticides, we need to look for alternative methods for vector control.  Possible use of Wolbachia bacteria as a biological control agent will be explored by determining the occurrence of Wolbachia in natural dengue vector populations.