Displaying publications 1 - 20 of 65 in total

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  1. Rozilawati H, Tanaselvi K, Nazni WA, Mohd Masri S, Zairi J, Adanan CR, et al.
    Trop Biomed, 2015 Mar;32(1):49-64.
    PMID: 25801254 MyJurnal
    Entomological surveillance was conducted in order to determine the abundance and to evaluate any changes of biological vectors or ecology, especially in the dengue outbreak areas. The abundance and breeding preference of Aedes albopictus and Aedes aegypti were conducted in selected dengue outbreak localities in three states of peninsular Malaysia namely Selangor, Federal Territory of Kuala Lumpur, and Penang Island using ovitraps and larval survey method. It was determined that Ae. albopictus was predominant in most of the localities and found to breed more outdoor than indoor. A wide range of breeding foci were recorded in this study. It was also determined that ovitrap method was more effective to detect the presence of Aedes mosquitoes when the larval survey was at low rate of infestation. The abundance of Ae. albopictus in dengue outbreak localities emphasis that the vector control programme should also target this species together with the primary dengue vector, Ae. aegypti.
    Matched MeSH terms: Aedes/physiology*
  2. Mohamad N, Zuharah WF
    Trop Biomed, 2014 Mar;31(1):166-73.
    PMID: 24862057 MyJurnal
    Toxorhynchites splendens larvae are a natural predator of dengue vector mosquito larvae, Aedes albopictus. This study was carried out to evaluate the predation rate of Tx. splendens third instar larvae on Ae. albopictus larvae in 24 h. Each predator was offered prey at a density between 10 to 50 individuals. Predation rate of Tx. splendens were also tested with two manipulated factors; various types of container and different water volumes. The experiment was evaluated in man-made containers (tin cans, plastic drinking glasses and rubber tires) and natural container (bamboo stumps) which were filled with different water volumes (full, half full, 1/4 full, and 1/8 full). The prey density and the characteristics of the container were found as significant factors which influence the predation rate of Tx. splendens. The predator consumed significantly more prey at higher prey densities (40 and 50 preys) compared to the lowest density (10 preys) (F=3.935, df=4, p=0.008). The results showed significantly higher consumption in horizontal shaped container of rubber tire than in vertical shape of bamboo stumps (F=3.100, df=3, p=0.029). However, the water volume had no significant effect on predation rate of Tx. splendens (F=1.736, df=3, p=0.162). We generally suggest that Tx. splendens is best to be released in discarded tires or any other containers with horizontal shape design with wide opening since Tx. splendens can become more effective in searching prey in this type of container design. This predator is also a suitable biocontrol candidates to be introduced either in wet and dry seasons in Malaysia.
    Matched MeSH terms: Aedes/physiology*
  3. Arbaoui AA, Chua TH
    Trop Biomed, 2014 Mar;31(1):134-42.
    PMID: 24862053 MyJurnal
    Since a safe and effective mass vaccination program against dengue fever is not presently available, a good way to prevent and control dengue outbreaks depends mainly on controlling the mosquito vectors. Aedes aegypti mosquito populations can be monitored and reduced by using ovitraps baited with organic infusions. A series of laboratory experiments were conducted which demonstrated that the bacteria in bamboo leaf infusion produce volatile attractants and contact chemical stimulants attractive to the female mosquitoes. The results showed that the female mosquitoes laid most of their eggs (59.9 ± 8.1 vs 2.9 ± 2.8 eggs, P<0.001) in bamboo leaf infusions when compared to distilled water. When the fresh infusion was filtered with a 0.45 μm filter membrane, the female mosquitoes laid significantly more eggs (64.1 ± 6.6 vs 4.9 ± 2.6 eggs, P<0.001) in unfiltered infusion. However when a 0.8 μm filter membrane was used, the female laid significantly more eggs (62.0 ± 4.3 vs 10.1 ± 7.8 eggs, P<0.001) in filtrate compared to a solution containing the residue. We also found that a mixture of bacteria isolated from bamboo leaf infusion serve as potent oviposition stimulants for gravid Aedes mosquitoes. Aedes aegypti laid significantly more eggs (63.3 ± 6.5 vs 3.1 ± 2.4 eggs, P<0.001) in bacteria suspension compared to sterile R2A medium. Our results suggest microbial activity has a role in the production of odorants that mediate the oviposition response of gravid mosquitoes.
    Matched MeSH terms: Aedes/physiology*
  4. Ahbirami R, Zuharah WF, Yahaya ZS, Dieng H, Thiagaletchumi M, Fadzly N, et al.
    Trop Biomed, 2014 Sep;31(3):456-65.
    PMID: 25382472
    Bioprospecting of plant-based insecticides for vector control has become an area of interest within the last two decades. Due to drawbacks of chemical insecticides, phytochemicals of plant origin with mosquito control potential are being utilized as alternative sources in integrated vector control. In this regard, the present study aimed to investigate oviposition deterring and oviciding potentials of Ipomoea cairica (L.) (Family: Convolvulaceae) crude leaf extract against dengue vectors, Aedes aegypti and Aedes albopictus. Ipomoea cairica is an indigenous plant that has demonstrated marked toxicity towards larvae of Ae. aegypti and Ae. albopictus. Leaves of I. cairica were extracted using Soxhlet apparatus with acetone as solvent. Oviposition deterrent activity and ovicidal assay was carried out in oviposition site choice tests with three different concentrations (50, 100, 450 ppm). Acetone extract of I. cairica leaf strongly inhibited oviposition with 100% repellence to Ae. aegypti at lower concentration of 100 ppm, while for Ae. albopictus was at 450 ppm. The oviposition activity index (OAI) values which ranged from -0.69 to -1.00 revealed that I. cairica demonstrated deterrent effect. In ovicidal assay, similar trend was observed whereby zero hatchability was recorded for Ae. aegypti and Ae. albopictus eggs at 100 and 450 ppm, respectively. It is noteworthy that I. cairica leaf extract had significantly elicited dual properties as oviposition deterrent and oviciding agent in both Aedes species. Reduction in egg number through oviposition deterring activity, reduction in hatching percentage and survival rates, suggested an additional hallmark of this plant to be integrated in Aedes mosquito control. Ipomoea cairica deserved to be considered as one of the potential alternative sources for the new development of novel plant based insecticides in future.
    Matched MeSH terms: Aedes/physiology
  5. Wan-Norafikah O, Nazni WA, Noramiza S, Shafa'ar-Ko'ohar S, Azirol-Hisham A, Nor-Hafizah R, et al.
    Trop Biomed, 2010 Dec;27(3):662-7.
    PMID: 21399609
    A preliminary study on the vertical dispersal of Aedes populations in high-rise apartments was carried out in Presint 9, Putrajaya, Malaysia. Ovitraps were placed indoors within four blocks of high-rise apartments from the ground floors (0.0 - 3.0 m) until up to the tenth floors (28.1 - 30.0 m). Aedes aegypti was the dominant species found in the ovitraps (87.85%), while Aedes albopictus was found in lower numbers. From total number of larvae collected (650), 40.92% of these larvae were obtained from the fourth block; Block D. The peak density of Aedes sp. was observed at level 6 (16.1 - 18.0 m), while Ae. aegypti was found until the tenth floor (28.1 - 30.0 m). In contrast, Ae. albopictus was found only up to the sixth floor (16.1 - 18.0 m). A poor correlation of the mean number of Aedes larvae collected with the level of high-rise apartments occupied (N=40; ρ=-0.349) was also observed which indicated the possibility of lesser Aedes populations to be found at higher level of high-rise apartments. Therefore, larger scale studies are strongly recommended to examine the vertical dispersal of Aedes mosquitoes.
    Matched MeSH terms: Aedes/physiology*
  6. Nyamah MA, Sulaiman S, Omar B
    Trop Biomed, 2010 Apr;27(1):33-40.
    PMID: 20562811 MyJurnal
    This cross-sectional study was to compare and categorize potential breeding sites of dengue vectors, Aedes aegypti and Aedes albopictus at three different places, namely, an urban (Taman Permas Jaya, Johor Bahru, Johor), a suburban (Kg. Melayu Gelang Patah, Johor Bahru, Johor) and a rural (Felda Simpang Waha, Kota Tinggi, Johor) habitats in Malaysia. Larval surveys were conducted once in every two months at each habitat over a period of 11 months from August 2000 until June 2001. There was a significant difference between the three study sites in terms of potential breeding sites inspected (p<0.001). There were more potential breeding sites found in the rural area when compared to the urban and suburban habitats. The mean Potential Container Index (PCI) values in descending order were as follows: rural habitat (57.72)>suburban (29.35)>urban habitat (16.97). Both breeding sites and potential breeding sites were the nominator and the total number of containers inspected as the denominator in the formula of PCI, thus the latter could be a potential indicator to initiate anti-dengue campaign at the community level to rid off potential Aedes breeding sites. The three most common potential breeding sites of Aedes species were similar for urban and suburban habitats (flower pots, pails and bowls respectively). However, flower pots, vases and tyres were the three most common potential breeding sites for the rural habitat. Another finding in this study was that various types of larval habitats were found indoors and outdoors for both species.
    Matched MeSH terms: Aedes/physiology*
  7. Lim KW, Sit NW, Norzahira R, Sing KW, Wong HM, Chew HS, et al.
    Trop Biomed, 2010 Aug;27(2):185-92.
    PMID: 20962714 MyJurnal
    A year-long ovitrap surveillance was conducted between November 2007 and October 2008 in two insular settlements (Kampung Pulau Ketam and Kampung Sungai Lima) within the Malaysian island of Pulau Ketam. Eighty standard ovitraps were placed indoors and outdoors of randomly selected houses/locations. Results demonstrated an endemic baseline Aedes population throughout the year without weekly large fluctuations. Kampung Pulau Ketam has high Aedes aegypti and Aedes albopictus population, but only Ae. aegypti was found in Kampung Sungai Lima. Aedes aegypti showed no preference for ovitraps placed indoor versus outdoor. However, as expected, significantly more outdoor ovitraps were positive for Ae. albopictus (p<0.05). Trends in Ae. albopictus and Ae. aegypti populations mirrored each other suggesting that common factors influenced these two populations.
    Matched MeSH terms: Aedes/physiology*
  8. Lee HL, Aramu M, Nazni WA, Selvi S, Vasan S
    Trop Biomed, 2009 Dec;26(3):312-9.
    PMID: 20237445
    The natural and artificial mating of laboratory bred Aedes albopictus and transgenic Aedes aegypti RIDL-513A-Malaysian strain was conducted. The experiment consisted of crossmating of homologous Ae. aegypti RIDL female symbol X Ae. aegypti RIDL male symbol and reciprocal Ae. aegypti RIDL female symbol X Ae. albopictus WT male symbol. The other set comprised homologous Ae. albopictus WT female symbol X Ae. albopictus WT male symbol and reciprocal Ae. albopictus WT female symbol X Ae. aegypti RIDL male symbol. This study demonstrated that reproductive barriers exist between these two species. Cross insemination occurred between A. albopictus male and Ae. aegypti female and their reciprocals. There was 26.67% and 33.33% insemination rate in Ae. aegypti RIDL female cross-mating with A. albopictus WT male and Ae. albopictus female cross-mating with Ae. aegypti RIDL male, respectively. There was 0% hatchability in both directions of the reciprocals. There was also no embryonation of these eggs which were bleached. Although none of the female Ae. albopictus WT was inseminated in the cross-mating with Ae. albopictus WT female symbol X Ae. aegypti RIDL male symbol, a total of 573 eggs were obtained. The homologous mating was very productive resulting in both high insemination rate and hatchability rates. Generally there was a significantly higher insemination rate with artificial mating insemination of homologous than with artificial mating of reciprocal crosses. Interspecific mating between Ae. aegypti RIDL and Ae. albopictus wild type was not productive and no hybrid was obtained, indicating absence of horizontal transfer of introduced RIDL gene in Ae. aegypti to Ae. albopictus.
    Matched MeSH terms: Aedes/physiology*
  9. Rozilawati H, Zairi J, Adanan CR
    Trop Biomed, 2007 Jun;24(1):83-94.
    PMID: 17568381 MyJurnal
    Ovitrap surveillance was conducted in a selected urban area and suburban area, ie. Taman Permai Indah(TPI) and Kampung Pasir Gebu (KPG) in Penang for 14 months. It was found that Aedes albopictus was the most abundant Aedes species in both study areas, even though a small percentage of Aedes aegypti and Culex quinquefasciatus were found to breed simultaneously in the same ovitrap. This study indicated that the main dengue vector was Ae. albopictus. A strong correlation was found between rainfall and egg population in both of the study sites (r = 0.982 and r = 0.918).
    Matched MeSH terms: Aedes/physiology*
  10. Nur Aida H, Abu Hassan A, Nurita AT, Che Salmah MR, Norasmah B
    Trop Biomed, 2008 Aug;25(2):117-25.
    PMID: 18948882
    A semi laboratory experiment using 3 cohorts of Aedes albopictus adults was performed to obtain age-specific mortality and fecundity information and to derive statistical estimates of some population growth parameters. Life expectancy was calculated for both males and females. The following population parameters were estimated: intrinsic rate of increase (rm= 0.21), net reproductive (replacement) rate (Ro= 68.70), age at mean cohort reproduction (To=10.55 days), birth rate (B=0.23), death rate (D=0.02) and generation time (G=20.14 days). The high rm/B (0.91) and B/D (11.50) ratios indicated the high colonizing ability of Ae. albopictus in nature.
    Matched MeSH terms: Aedes/physiology*
  11. Oli K, Jeffery J, Vythilingam I
    Trop Biomed, 2005 Dec;22(2):249-51.
    PMID: 16883295 MyJurnal
    Adult mosquito collections were conducted for 12 weeks in two residential areas in Kuala Lumpur. The CDC light traps were compared using dry ice and yeast as sources of carbon dioxide attractants for mosquitoes. The efficacy of the dry ice baited trap was significant over yeast generated CO2 trap. The predominant species obtained were Culex quinquefasciatus, Stegomyia albopicta and Armigeres subalbatus.
    Matched MeSH terms: Aedes/physiology
  12. Chen CD, Nazni WA, Lee HL, Seleena B, Mohd Masri S, Chiang YF, et al.
    Trop Biomed, 2006 Dec;23(2):224-7.
    PMID: 17322826 MyJurnal
    Ovitrap surveillance was conducted in four dengue endemic areas in Kuala Lumpur and Selangor, Malaysia to determine the distribution and percentage of mixed breeding of both Aedes aegypti and Aedes albopictus. The percentage of mixed breeding in all study sites both indoors and outdoors accounted for 10 to 32 % from the total ovitraps collected. Ae. aegypti was found at a higher frequency than Ae. albopictus in these ovitraps. This study again indicates that ovitrap is a sensitive tool to attract gravid females of more than one mosquito species to oviposit in the container.
    Matched MeSH terms: Aedes/physiology*
  13. Rozilawati H, Lee HL, Mohd Masri S, Mohd Noor I, Rosman S
    Trop Biomed, 2005 Dec;22(2):143-8.
    PMID: 16883280 MyJurnal
    Field bioefficacy of residual-sprayed deltamethrin against Aedes vectors was evaluated in an urban residential area in Kuala Lumpur. The trial area consisted of single storey wood-brick houses and a block of flat. The houses were treated with outdoor residual spraying while the flat was used as an untreated control. Initial pre-survey using ovitrap surveillance indicated high Aedes population in the area. Deltamethrin WG was sprayed at a dosage of 25mg/m2 using a compression sprayer. The effectiveness of deltamethrin was determined by wall bioassay and ovitrap surveillance. The residual activity of 25mg/m2 deltamethrin was still effective for 6 weeks after treatment, based on biweekly bioassay results. Bioassay also indicated that both Aedes aegypti and Aedes albopictus were more susceptible on the wooden surfaces than on brick. Aedes aegypti was more susceptible than Ae. albopictus against deltamethrin. Residual spraying of deltamethrin was not very effective against Aedes in this study since the Aedes population in the study area did not reduce as indicated by the total number of larvae collected using the ovitrap (Wilcoxon Sign Test, p> 0.05). Further studies are required to improve the effectiveness of residual spraying against Aedes vectors.
    Matched MeSH terms: Aedes/physiology
  14. Nazni WA, Lee HL, Dayang HA, Azahari AH
    PMID: 19323032
    Reciprocal and homologous mating experiments between Malaysian Aedes aegypti and Aedes albopictus mosquitoes were conducted in the laboratory. Two methods were employed, namely an artificial mating technique and a natural cage mating technique. The study demonstrated there exists a strong reproductive isolation between Ae. aegypti and Ae. albopictus. Insemination occurred in cross-mating experiments between Ae. aegypti females and Ae. albopictus males and also between Ae. albopictus females and Ae. aegypti males. Cross mating between Ae. aegypti females and Ae. albopictus males produced more eggs than that between Ae. albopictus females and Ae. aegypti males with both artificial mating and natural cage mating techniques. The matings did not result in the production of viable eggs by the females. No embryonation of these eggs was observed when the eggs were bleached. With homologous mating Aedes aegypti produced significantly greater numbers of eggs compared to Aedes albopictus mosquitoes, and all the eggs hatched successfully.
    Matched MeSH terms: Aedes/physiology*
  15. Chua KB, Chua IL, Chua IE, Chua KH
    PMID: 16438137
    A prospective field study was carried out to investigate any preferential differences of gravid female Aedes mosquitoes in ovipositing their eggs in man-made containers placed in different environmental conditions. The findings of this study show that gravid female Aedes mosquitoes preferred to breed in containers found in the outdoor garden than those placed on the patio and or inside the house. The findings also show that if the breeding habitats in the garden were removed, they would favorably use the breeding habitats found on the patio or inside the house as alternatives. An incidental interesting finding in this study shows that ultra-low volume fogging of insecticides using the vehicle-mounted equipment carried out outside the house may promote the gravid female Aedes mosquitoes to enter the house to breed.
    Matched MeSH terms: Aedes/physiology*
  16. Chua KB, Chua IL, Chua IE, Chua KH
    PMID: 15689073
    A study was made of the oviposit behavior of gravid female Aedes mosquitos in man-made habitats under field conditions. The study showed that the gravid female Aedes mosquitos preferred containers with relatively easy access but not too open to external environmental influence. The dark surface of the containers served as the initial and long-range attractant to the breeding sites. Volatile chemicals generated by the decaying vegetation in the container may serve as a close-range attractant. Finally, the water quality and the quantity of 'food' derived from decaying vegetative matter in the water determined the amount of eggs deposited in each container. The study confirmed previous findings that each gravid female Aedes mosquito had the tendency to lay her eggs in more than one container. However, the results of the study suggests that under favorable conditions, each gravid female Aedes mosquito could be encouraged to lay all her eggs in a single breeding site.
    Matched MeSH terms: Aedes/physiology*
  17. Afizah AN, Mahirah MN, Azahari AH, Asuad MK, Nazni WA, Lee HL
    PMID: 26863856
    Ovitrap surveillance was conducted in 2012 and 2006 in Malay and Aboriginal Villages on Carey Island. In each village, standard ovitraps were placed indoors and outdoors at randomly selected houses/locations. All L3 larvae recovered were identified up to species level. Results demonstrated that only larvae of Aedes albopictus were found in all the positive ovitraps placed indoors and outdoors. In 2012, a high ovitrap index (OI) of 66.7% indoor and 84.0% outdoor in the Malay Village; and 62.5% indoor and 88.0% outdoor in Aboriginal Village with an apparent absence of Aedes aegypti. In 2006, a 100% OI was recorded in all ovitraps set indoors and outdoors in both villages.
    Matched MeSH terms: Aedes/physiology*
  18. Chang MS, Jute N
    PMID: 7777923
    An Aedes survey using various larval survey methods was conducted in 12 urban housing areas and 29 vacant lands in Sibu town proper. Aedes albopictus larvae were found in all areas surveyed while Aedes aegypti larvae were present in 10 localities and 4 vacant lands. There were no significant difference in the house index, breteau and larval density index of these two Aedes (Stegomyia) species from the survey areas. The proportion of containers positive with Ae. aegypti and Ae. albopictus in area outside the house compound and near the house fencing were 3.2 times higher than outdoor compound. The indoor/outdoor breeding ratio for Ae. aegypti alone is 1.6:1. The most preferred breeding habitats outdoor were plastic cups and used tires while indoor habitats were ant traps and flower vases. In the vacant lands, the average number of larvae per containers was significantly higher than in houses and over 51% of the containers inspected were positive. Shared breeding between Ae. aegypti and Ae. albopictus larvae accounted for 9% in house surveys and 4.5% in vacant land survey. The use of various methods in Aedes larval survey may provide essential information in the study of vector epidemiology in dengue and dengue hemorrhagic fever transmission.
    Matched MeSH terms: Aedes/physiology*
  19. Ahmad R, Chu WL, Ismail Z, Lee HL, Phang SM
    PMID: 15272748
    The effect of ten microalgal chlorophytes isolated from mosquito breeding containers on the survival, larval development and adult body size of the mosquito Aedes aegypti was investigated. All larvae fed with six of the microalgal isolates died after 7 days. These isolates were found to be resistant to digestion by mosquito larvae. Delayed pupation and body size reduction of the mosquitos fed with Chlorococcum UMACC 218 and Scenedesmus UMACC 220 were observed. In contrast, larvae fed with Ankistrodesmus convolutus UMACC 101 and Chlorococcum UMACC 213 were bigger in size than those fed with normal insectory feed. The present study showed that microalgal chlorophytes have the potential to be used as larvicidal agents for mosquitos.
    Matched MeSH terms: Aedes/physiology*
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