Bionomic Of Aedes Species And The Susceptibility To Insecticides In Penang Island, Malaysia

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Date
2015-10
Authors
Mohd Ngesom, Ahmad Mohiddin
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A field study was conducted in Flat Hamna (FH), Kampung Sungai Gelugor (KSG) and Kampung Tanjung Tokong (KTT) for a period of 14 months from January 2010 until February 2011. The objectives of this study are to determine the population and distribution of Aedes mosquito and the resistance status among the larvae and adult mosquitoes against selected insecticides that have been used in the vector control activity in Penang Island. The result showed that Ae. albopictus was a dominant species in Flat Hamna, Kampung Sungai Gelugor and Kampung Tanjung Tokong. It was found at higher frequency in both indoor and outdoor compared to Ae. aegypti. In indoor, overall Ae. albopictus accounts high number of larvae collection in Flat Hamna (28.59±1.10), Kampung Sungai Gelugor (19.94±1.59) and Kampung Tanjung Tokong (24.10±1.80) as compared to Ae. aegypti. However, Ae. aegypti was preferred to breed outdoor with 186% higher than indoor. A negative correlation was found between the ovitrap index and temperature in Flat Hamna and Kampung Sungai Gelugor. Whereas, positive correlation was recorded between ULV activity with number of collected larvae from Flat Hamna and Kampung Sungai Gelugor except from Kampung Tanjung Tokong. Aedes albopictus FH strain showed incipient resistance scale to all commonly used insecticides against permethrin, deltamethrin and malathion which caused 93%, 97% and 87% of mortality respectively using WHO adult bioassay diagnostic dose kit. KSG strain also started to develop resistance towards permethrin, whereas the KTT strain was still susceptible to all insecticides. However, statistically significant differences were detected between all insecticides tested and localities (F(2,6) = 4.798, p = 0.008). The highest KdT95 of 42.26 min occurred in KTT strain to deltamethrin but showed no significant difference compared to other insecticides (F(2,6) = 3.316, p = 0.107). The highest RR95 value of was detected in the FH strain against permethrin with 1.93 fold. Larval bioassays were also carried out to determine the lethal time (LT50 and LT95) and resistance ratio (RR50 and RR95) to temephos and Bacillus thuringiensis israelensis (Bti). The result showed that Ae. albopictus from FH, KSG, and KTT were susceptible to Bti and temephos. This study found that the abundance of larvae would be increased after two or three month following the rainy season with a high number of OI. As conclusion the application of insecticide in vector control in Penang on selected areas still relevant and effective tool to control Aedes mosquito populations.
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