The ecology and biology of aedes aegypti (l.) and aedes albopictus (skuse) (diptera: culicidae) and the resistance status of aedes albopictus (field strain) against organophosphates in Penang, Malaysia
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Date
2006
Authors
Sivanathan, Manorenjitha Malar
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Abstract
Outdoor Ovitrap surveys were carried out in two suburban locations in Penang; Paya Terubong (Air Itam) and Bagan Dalam (Butterworth). Statistical analyses showed a strong correlation between rainfall and egg population in Paya Terubong while Bagan Dalam showed a moderate correlation. Almost 99 % eggs collected in Paya Terubong and 95 % of eggs collected in Bagan Dalam emerged as Aedes albopictus in the laboratory. Only a small percentage of Aedes aegypti emerged from the paddles collected in both locations. Aedes albopictus was the most predominant outdoor species in both sampling area.
Aedes aegypti‘s eggs and Aedes albopictus’s eggs which were submerged after 1 month and 3 weeks, respectively, produced the highest hatching rate. The development from the first instar larva to adult stage for Aedes aegypti (VCRU-strain), Aedes aegypti (BD-strain),Aedes albopictus (VCRU-strain) dan Aedes albopictus (PT-strain) was about 6.25 ± 0.26 days, 6.84 ± 0.30 days, 8.36 ± 0.18 days dan 7.73 ± 0.24 days, respectively. Female Aedes albopictus (VCRU-strain) fed with 10% sucrose only showed the highest mean survival which was 55.5 ± 1.25 days while male Aedes albopictus (PT-strain) fed with 10% sucrose recorded 37.7 ± 0.74 days which was the shortest mean survival. Gonotrophic cycle for Aedes aegypti (BD-strain) and Aedes albopictus (PT-strain) were 3.00 ± 0.83 days
and 2.73 ± 0.18 days, respectively. Larvae reared under optimal condition showed a very short pupation period and low mortality rate compared to larvae reared under suboptimal condition. Larvae reared under optimal condition produce more eggs. The number of eggs recorded for Aedes aegypti (BD-strain) was 86.2 ± 2.20 eggs and for Aedes albopictus (PT-strain) was 67.5 ± 4.37 eggs. Both Aedes sp. showed preference to cone shaped substrate than flat substrate. Number of eggs recorded on cone shaped substrates for Aedes aegypti (BD-strain) and Aedes albopictus (PT-strain) was 122.7 ± 1.83 eggs and 96.5 ± 4.08 eggs respectively.
Field collected Aedes albopictus larvae are still susceptible to temephos although temephos has been used in Penang for a long period. No resistance was shown by Aedes albopictus (field strain) when tested against other organophosphate larvicides. Chlorpyrifos showed the highest insecticidal activity compared to other larvicides.
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Keywords
Aedes aegypti , Aedes albopictus , Organophosphates