Molecular Identification And Genetics Status Of Aedes Mosquitoes In Penang

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Date
2016-06
Authors
Mustafa Kamal, Nur Zawani
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Abstract
Dengue fever is one of the mosquito-borne diseases affecting millions of people worldwide. The cases of dengue fever are increasing rapidly around the world including in Malaysia. Research has been done towards the two main vectors of dengue fever which are Aedes aegypti and Aedes albopictus to help in designing the best vector control strategy. The present study was conducted to identify mosquitoes species in 31 locations in Penang using cytochrome oxidase subunit 1 (COI) marker and to examine the population genetics structure of Ae. aegypti and Ae. albopictus. Identification using COI marker showed that, out of 497 mosquito larvae that were successfully genotyped from 31 locations, 92.35 % were from the genus Aedes, 7.04 % from the genus Culex and 0.60 % from Toxorhynchites. Study on population genetics structure of Aedes mosquitoes revealed 39 haplotypes from 106 larvae samples of Ae. aegypti and 64 haplotypes out of 328 samples of Ae. albopictus were analyzed. Low nucleotide (π) and high haplotype diversity (h) was recorded in most of the populations for both mosquito species. This pattern suggested the occurrence of population expansion which can lead to retention of new mutations. The result was supported by neutrality test; Tajima’s D and Fu’s Fs which showed negative results for most of the populations studied. However, mismatch distribution analysis showed different results for Ae. albopictus and Ae. aegypti where the mismatch distribution graph showed unimodal and bimodal characteristics respectively. Unimodal characteristic indicated that the Ae. albopictus population has undergone recent demographic expansion while bimodal distribution hypothesized that the migration rate of Ae. aegypti is low. The phylogenetic tree for both species showed a low bootstrap value with no genetic structure and the result was further corroborated by minimum spanning network analysis which showed the mixture of haplotypes in different locations in Penang. The hypothesis of limited phylogeographic partitioning is strengthen by low genetic distance within and between population and pairwise FST values which showed no significant difference except for some Medan Mahsuri. Analysis of molecular variance (AMOVA) also revealed that most of the mtDNA variation occurred among samples within population. Thus, all of the results concluded that there is no population genetics structure of Ae. aegypti and Ae. albopictus in 31 locations in Penang. Further research should be done by using other genetic markers such as microsatellite marker to investigate the population genetics structure of Aedes mosquitoes in Penang Research on insecticide resistance gene also shoul be carried out to investigate whether Aedes mosquitoes in Penang area still can be eliminated by using chemicals or otherwise.
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Identify mosquitoes species in 31 locations in Penang , using cytochrome oxidase subunit 1 (COI) marker
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