Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides r... more Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides remain the most effective vector control approach forAedesmosquitoes. Four main classes of insecticides are widely used for mosquito control: organochlorines, organophosphates, pyrethroids and carbamates. Here, we review the distribution of dengue fever from 2000 to 2020 and its associated mortality in Southeast Asian countries, and we gather evidence on the trend of insecticide resistance and its distribution in these countries since 2000, summarising the mechanisms involved. The prevalence of resistance to these insecticides is increasing in Southeast Asia, and the mechanisms of resistance are reported to be associated with target site mutations, metabolic detoxification, reduced penetration of insecticidesviathe mosquito cuticle and behavioural changes of mosquitoes. Continuous monitoring of the status of resistance and searching for alternative control measures will be critical for mi...
Iranian Journal of Pharmaceutical Research : IJPR, 2019
Essential oil of Citrus family plant is known to have repellent effect against mosquito. Unfortun... more Essential oil of Citrus family plant is known to have repellent effect against mosquito. Unfortunately, due to its high volatility effect, its repellency effect was compromised. The incorporation of essential oil in a microencapsulation formulation has been shown to help improve the stability and potency of the repellent. In this study, Citrus grandis peel oil (CGPO) was encapsulated by using the interfacial precipitation chemistry technique. The microencapsulated CGPO was then formulated into lotion form to produce topical repellent formulation. This study includes the characterization of microcapsules with regards to the morphology, size distribution, zeta potential, Fourier Transmission Infrared spectrophotometer (FTIR), and Thermogravity analysis (TGA). The effectiveness of the microencapsulated CGPO-lotion formulation against mosquitoes was evaluated in the laboratory setting. Results indicated that CGPO have been successfully encapsulated with 6.5 µm in diameter and zeta poten...
... Different coils containing A. vera, A. indica, E. longifolia, F. adenophylla and C. nardus we... more ... Different coils containing A. vera, A. indica, E. longifolia, F. adenophylla and C. nardus were cut down to pieces weighing 1.5 g each. ... Malaysia: Pelandok Publications, 1995:205. 6. I Jantan, ZM Zaki and R Ahmad. Pertanika J Sci Technol 4 (1996), p. 51. ...
Essential oils have been widely used as an active ingredient in mosquito repellent products. Howe... more Essential oils have been widely used as an active ingredient in mosquito repellent products. However, essential oils are highly unstable and prone to degradation when exposed to the environment during storage. Microencapsulation techniques help to maintain the stability of molecules in essential oils that are sensitive to environmental stress, and therefore improve shelf life. In this study, the physical stability and efficacy of a repellent formulation consisting of encapsulated Citrus grandis essential oil (CGEO) were evaluated under different storage conditions over a 12-month period by comparing the formulation with a non-encapsulated formulation. The formulations were both stored under two different storage conditions, i.e., 25 ± 2 °C/60% ± 5% relative humidity (RH) and 40 ± 2 °C/75% RH ± 5%, for 12 months. Droplet size, zeta potential, and pH value were measured after 1, 6, and 12 months of storage to determine their stability. For the study of efficacy, each formulation was t...
The Southeast Asian journal of tropical medicine and public health, 2009
Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes al... more Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes albopictus Skuse cell line and used to infect adult female Aedes aegypti mosquitoes. Each serotype was mixed separately with fresh human erythrocytes and fed to adult female mosquitoes using an artificial membrane feeding technique. Fully engorged mosquitoes were selected and retained at 26 degrees C, 28 degrees C and 30 degrees C to observe dengue virus development in Aedes vectors. Virus detection was carried out by reverse-transcriptase polymerase chain reaction (RT-PCR). The virus was first detected on Day 9 at 26 degrees C and 28 degrees C and on Day 5 at 30 degrees C for both dengue 2 and 4. The study shows the incubation period of the viruses decreased when the extrinsic incubation temperature increases.
Discovering new mosquitocidal agent is the research focus of government authorities, researchers ... more Discovering new mosquitocidal agent is the research focus of government authorities, researchers and industrial investors. Seaweeds serve a great potential in providing unique components and compounds with effective bioactivity. In the present study, seaweed species collected from West Malaysia were evaluated for their larvicidal and adulticidal activities according to WHO guidelines. Extracts were prepared by maceration of dried seaweeds in methanol. Of the 15 species tested, the green seaweed Bryopsis pennata exhibited the strongest larvicidal activity against Aedes aegypti (LC50 value: 156.97 μg/ml) and Ae. albopictus (LC50 value: 177.50 μg/ml). The brown seaweed Sargassum siliquosum had the strongest adulticidal effect against Ae. aegypti (LC50 value: 17.53 mg/cm2) and Ae. albopictus (LC50 value: 35.40 mg/cm2), among the 11 species tested. Larvae and female adults showed signs of intoxication, such as restless movement, tremor, paralysis, and followed by eventual death, after ex...
The effectiveness of insecticide-based dengue control interventions is very much influenced by th... more The effectiveness of insecticide-based dengue control interventions is very much influenced by the insecticide resistance status of the mosquito at the targeted areas. This study aims to determine the insecticide resistance status and the enzymatic activity. WHO adult bioassays conducted on Ae. aegypti and Ae. albopictus from 12 dengue hotspots outbreak areas in Kuala Lumpur and Selangor towards insecticides currently and historically used for mosquito control in Malaysia which include two pyrethroids, one organoclorine, one organophosphate and one carbamate. Biochemical enzyme assays were conducted and the activity of enzymes αEsterase, MFO, GST and AChE were examined. Kruskal-Wallis H, Mann-Whitney U and ANOVA test were used to determine the significant difference of the mortality between insecticides and localities, the enzymes activity between the field and the lab strains, and the enzymes activity within all field strains. Ae. aegypti from all sites have developed resistance to...
The protein profiles of DENV-2 and DENV-4 viruses-infected adult Aedes aegypti were analysed usin... more The protein profiles of DENV-2 and DENV-4 viruses-infected adult Aedes aegypti were analysed using Coomassie-stained SDS-PAGE samples. For this study, adult female mosquitoes were infected orally with either DENV-2 or DENV-4 virus using spiked human blood samples. The infections in the individual mosquitoes were confirmed using the reverse transcription-polymerase chain reaction (RT-PCR). From the SDS-PAGE analyses, a total of 11 proteins with molecular weights of 22 kDa to greater than 181.8 kDa were identified in DENV-2 and DENV-4-infected mosquito homogenates. Three proteins (Mr 49, 64 and 200 kDa) from DENV-2-infected mosquitoes and five proteins (Mr 49, 50, 60, 135 and 200 kDa) from DENV-4-infected mosquitoes were identified at higher concentrations than in uninfected controls. Further work is now needed to specifically identify these proteins and study their biological roles in DENV infections.
Dengue is an increasing threat in Malaysia, particularly in the more densely populated regions of... more Dengue is an increasing threat in Malaysia, particularly in the more densely populated regions of the country. We present an Artificial Intelligence driven model in predicting Aedes outbreak, using predictors of weather variables and vector indices sourced from the Ministry of Health. Analysis and predictions to estimate Aedes populations were conducted, with its results being used to infer the possibility of dengue outbreaks at pre-determined localities around the Klang Valley, Malaysia. A Bayesian Network machine learning technique was employed, with the model being trained using predictor variables such as temperature, rainfall, date of onset and notification, and vector indices such as the Ae. albopictus count, Ae. aegypti count and larval count. The interfaces of the system were developed using the C# language for Server-side configuration and programming, and HTML, CSS and JavaScript for the Client Side programming. The model was then used to predict the population of Aedes at...
A large scale study was conducted to elucidate the true relationship among entomological, epidemi... more A large scale study was conducted to elucidate the true relationship among entomological, epidemiological and environmental factors that contributed to dengue outbreak in Malaysia. Two large areas (Selayang and Bandar Baru Bangi) were selected in this study based on five consecutive years of high dengue cases. Entomological data were collected using ovitraps where the number of larvae was used to reflect Aedes mosquito population size; followed by RT-PCR screening to detect and serotype dengue virus in mosquitoes. Notified cases, date of disease onset, and number and type of the interventions were used as epidemiological endpoint, while rainfall, temperature, relative humidity and air pollution index (API) were indicators for environmental data. The field study was conducted during 81 weeks of data collection. Correlation and Autoregressive Distributed Lag Model were used to determine the relationship. The study showed that, notified cases were indirectly related with the environmen...
Within the last century, increases in human movement and globalization of trade have facilitated ... more Within the last century, increases in human movement and globalization of trade have facilitated the establishment of several highly invasive mosquito species in new geographic locations with concurrent major environmental, economic and health consequences. The Asian tiger mosquito, Aedes albopictus, is an extremely invasive and aggressive daytime-biting mosquito that is a major public health threat throughout its expanding range. We used 13 nuclear microsatellite loci (on 911 individuals) and mitochondrial COI sequences to gain a better understanding of the historical and contemporary movements of Ae. albopictus in the Indo-Pacific region and to characterize its population structure. Approximate Bayesian computation (ABC) was employed to test competing historical routes of invasion of Ae. albopictus within the Southeast (SE) Asian/Australasian region. Our ABC results show that Ae. albopictus was most likely introduced to New Guinea via mainland Southeast Asia, before colonizing the...
Many essential oils have been reported as natural sources of insect repellents; however, due to h... more Many essential oils have been reported as natural sources of insect repellents; however, due to high volatility, they present low repellent effect. Formulation technique by using microencapsulation enables to control the volatility of essential oil and thereby extends the duration of repellency. In this study, the effectiveness of microencapsulated essential oils of Alpinia galanga, Citrus grandis and C. aurantifolia in the lotion formulations were evaluated against mosquito bites. Essential oils and N,N-Diethyl-3-methylbenzamide (DEET) were encapsulated by using interfacial pre- cipitation techniques before incorporation into lotion base to form microencapsulated (ME) formulation. The pure essential oil and DEET were also prepared into lotion base to produce non-encapsulated (NE) formulation. All the prepared formulations were assessed for their repellent activity against Culex quinquefasciatus under laboratory condition. Field evaluations also were conducted in three different stu...
Journal of the American Mosquito Control Association, 2016
Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Ting... more Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Tinggi District, Johor State, Malaysia, 3 plants selected for study, Citrus aurantifolia (leaves), Citrus grandis (fruit peel), and Alpinia galanga (rhizome), were extracted using hydrodistillation to produce essential oils. These essential oils were then formulated as a lotion using a microencapsulation process and then tested for their repellent effect against Aedes aegypti. N,N-diethyl-m-toluamide (deet) was also prepared in the same formulation and tested for repellency as controls. Four commercial plant-based repellent (KAPS(®), MozAway(®), BioZ Natural(®), and Mosiquard(®)) also were incorporated in the bioassay for comparison purposes. Bioassays revealed that at 20% concentration all repellent formulations demonstrated complete protection for 2 h and >90% for 4 h post-application. The A. galanga-based formulation provided the greatest level of protection (98.91%), which extended fo...
ABSTRAK Ciri toksik minyak pati dari lapan belas spesies tumbuhan keatas instar keempat larva tig... more ABSTRAK Ciri toksik minyak pati dari lapan belas spesies tumbuhan keatas instar keempat larva tiga nyamuk vektor (Anopheles maculatus, Aedes aegypti dan Culex quinquejasciatus) telah dikaji. Minyak pati daripada daun Litsea elliptica adalah yang paling efektif, menunjukkan ...
To investigate the larvicidal activity, inhibition effect on development, histopathological alter... more To investigate the larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by the extracts derived from seaweeds Bryopsis pennata (B. pennata), Sargassum binderi (S. binderi) and Padina australis in Aedes aegypti (Ae. aegypti) larvae and to characterize the phytochemical components of the three seaweeds. Larvicidal activity of the seaweeds towards the larvae of Ae. aegypti was determined according to WHO. The inhibition effect of seaweeds was assessed by determining the mortality, adult emergence rate, larval and pupa duration of the treated larvae. Histopathological effect on midgut epithelium of larvae and morphological aberration induced by the methanol extracts were examined. Phytochemical analysis was done to determine the presence of alkaloids, saponins, steroids and terpenoids in the seaweeds. Chloroform partition of B. pennata extract exhibited the strongest larvicidal activity (LC50 = 82.55 μg/mL), followed by methanol extract of B. pennata (LC50 = 160.07 μg/mL) and chloroform partition of S. binderi extract (LC50 = 192.43 μg/mL). The methanol extract of S. binderi exhibited the strongest effect on prolongation of larval period (1.5-fold longer as compared to control) and resulted in strongest inhibition effect in adult emergence (98.67%). The histopathological study showed that larvae treated with seaweed extracts had cytopathological alteration of the midgut epithelium. The morphological observation revealed that the anal papillae and terminal spiracles of larvae were the common sites of aberrations. The study provided information on various effects of seaweed extracts on Ae. aegypti. Further investigation on identifying the active compounds and their mechanisms of action is recommended.
Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides r... more Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides remain the most effective vector control approach forAedesmosquitoes. Four main classes of insecticides are widely used for mosquito control: organochlorines, organophosphates, pyrethroids and carbamates. Here, we review the distribution of dengue fever from 2000 to 2020 and its associated mortality in Southeast Asian countries, and we gather evidence on the trend of insecticide resistance and its distribution in these countries since 2000, summarising the mechanisms involved. The prevalence of resistance to these insecticides is increasing in Southeast Asia, and the mechanisms of resistance are reported to be associated with target site mutations, metabolic detoxification, reduced penetration of insecticidesviathe mosquito cuticle and behavioural changes of mosquitoes. Continuous monitoring of the status of resistance and searching for alternative control measures will be critical for mi...
Iranian Journal of Pharmaceutical Research : IJPR, 2019
Essential oil of Citrus family plant is known to have repellent effect against mosquito. Unfortun... more Essential oil of Citrus family plant is known to have repellent effect against mosquito. Unfortunately, due to its high volatility effect, its repellency effect was compromised. The incorporation of essential oil in a microencapsulation formulation has been shown to help improve the stability and potency of the repellent. In this study, Citrus grandis peel oil (CGPO) was encapsulated by using the interfacial precipitation chemistry technique. The microencapsulated CGPO was then formulated into lotion form to produce topical repellent formulation. This study includes the characterization of microcapsules with regards to the morphology, size distribution, zeta potential, Fourier Transmission Infrared spectrophotometer (FTIR), and Thermogravity analysis (TGA). The effectiveness of the microencapsulated CGPO-lotion formulation against mosquitoes was evaluated in the laboratory setting. Results indicated that CGPO have been successfully encapsulated with 6.5 µm in diameter and zeta poten...
... Different coils containing A. vera, A. indica, E. longifolia, F. adenophylla and C. nardus we... more ... Different coils containing A. vera, A. indica, E. longifolia, F. adenophylla and C. nardus were cut down to pieces weighing 1.5 g each. ... Malaysia: Pelandok Publications, 1995:205. 6. I Jantan, ZM Zaki and R Ahmad. Pertanika J Sci Technol 4 (1996), p. 51. ...
Essential oils have been widely used as an active ingredient in mosquito repellent products. Howe... more Essential oils have been widely used as an active ingredient in mosquito repellent products. However, essential oils are highly unstable and prone to degradation when exposed to the environment during storage. Microencapsulation techniques help to maintain the stability of molecules in essential oils that are sensitive to environmental stress, and therefore improve shelf life. In this study, the physical stability and efficacy of a repellent formulation consisting of encapsulated Citrus grandis essential oil (CGEO) were evaluated under different storage conditions over a 12-month period by comparing the formulation with a non-encapsulated formulation. The formulations were both stored under two different storage conditions, i.e., 25 ± 2 °C/60% ± 5% relative humidity (RH) and 40 ± 2 °C/75% RH ± 5%, for 12 months. Droplet size, zeta potential, and pH value were measured after 1, 6, and 12 months of storage to determine their stability. For the study of efficacy, each formulation was t...
The Southeast Asian journal of tropical medicine and public health, 2009
Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes al... more Dengue 2 and 4 viruses obtained from dengue-infected patients were maintained in a C6/36 Aedes albopictus Skuse cell line and used to infect adult female Aedes aegypti mosquitoes. Each serotype was mixed separately with fresh human erythrocytes and fed to adult female mosquitoes using an artificial membrane feeding technique. Fully engorged mosquitoes were selected and retained at 26 degrees C, 28 degrees C and 30 degrees C to observe dengue virus development in Aedes vectors. Virus detection was carried out by reverse-transcriptase polymerase chain reaction (RT-PCR). The virus was first detected on Day 9 at 26 degrees C and 28 degrees C and on Day 5 at 30 degrees C for both dengue 2 and 4. The study shows the incubation period of the viruses decreased when the extrinsic incubation temperature increases.
Discovering new mosquitocidal agent is the research focus of government authorities, researchers ... more Discovering new mosquitocidal agent is the research focus of government authorities, researchers and industrial investors. Seaweeds serve a great potential in providing unique components and compounds with effective bioactivity. In the present study, seaweed species collected from West Malaysia were evaluated for their larvicidal and adulticidal activities according to WHO guidelines. Extracts were prepared by maceration of dried seaweeds in methanol. Of the 15 species tested, the green seaweed Bryopsis pennata exhibited the strongest larvicidal activity against Aedes aegypti (LC50 value: 156.97 μg/ml) and Ae. albopictus (LC50 value: 177.50 μg/ml). The brown seaweed Sargassum siliquosum had the strongest adulticidal effect against Ae. aegypti (LC50 value: 17.53 mg/cm2) and Ae. albopictus (LC50 value: 35.40 mg/cm2), among the 11 species tested. Larvae and female adults showed signs of intoxication, such as restless movement, tremor, paralysis, and followed by eventual death, after ex...
The effectiveness of insecticide-based dengue control interventions is very much influenced by th... more The effectiveness of insecticide-based dengue control interventions is very much influenced by the insecticide resistance status of the mosquito at the targeted areas. This study aims to determine the insecticide resistance status and the enzymatic activity. WHO adult bioassays conducted on Ae. aegypti and Ae. albopictus from 12 dengue hotspots outbreak areas in Kuala Lumpur and Selangor towards insecticides currently and historically used for mosquito control in Malaysia which include two pyrethroids, one organoclorine, one organophosphate and one carbamate. Biochemical enzyme assays were conducted and the activity of enzymes αEsterase, MFO, GST and AChE were examined. Kruskal-Wallis H, Mann-Whitney U and ANOVA test were used to determine the significant difference of the mortality between insecticides and localities, the enzymes activity between the field and the lab strains, and the enzymes activity within all field strains. Ae. aegypti from all sites have developed resistance to...
The protein profiles of DENV-2 and DENV-4 viruses-infected adult Aedes aegypti were analysed usin... more The protein profiles of DENV-2 and DENV-4 viruses-infected adult Aedes aegypti were analysed using Coomassie-stained SDS-PAGE samples. For this study, adult female mosquitoes were infected orally with either DENV-2 or DENV-4 virus using spiked human blood samples. The infections in the individual mosquitoes were confirmed using the reverse transcription-polymerase chain reaction (RT-PCR). From the SDS-PAGE analyses, a total of 11 proteins with molecular weights of 22 kDa to greater than 181.8 kDa were identified in DENV-2 and DENV-4-infected mosquito homogenates. Three proteins (Mr 49, 64 and 200 kDa) from DENV-2-infected mosquitoes and five proteins (Mr 49, 50, 60, 135 and 200 kDa) from DENV-4-infected mosquitoes were identified at higher concentrations than in uninfected controls. Further work is now needed to specifically identify these proteins and study their biological roles in DENV infections.
Dengue is an increasing threat in Malaysia, particularly in the more densely populated regions of... more Dengue is an increasing threat in Malaysia, particularly in the more densely populated regions of the country. We present an Artificial Intelligence driven model in predicting Aedes outbreak, using predictors of weather variables and vector indices sourced from the Ministry of Health. Analysis and predictions to estimate Aedes populations were conducted, with its results being used to infer the possibility of dengue outbreaks at pre-determined localities around the Klang Valley, Malaysia. A Bayesian Network machine learning technique was employed, with the model being trained using predictor variables such as temperature, rainfall, date of onset and notification, and vector indices such as the Ae. albopictus count, Ae. aegypti count and larval count. The interfaces of the system were developed using the C# language for Server-side configuration and programming, and HTML, CSS and JavaScript for the Client Side programming. The model was then used to predict the population of Aedes at...
A large scale study was conducted to elucidate the true relationship among entomological, epidemi... more A large scale study was conducted to elucidate the true relationship among entomological, epidemiological and environmental factors that contributed to dengue outbreak in Malaysia. Two large areas (Selayang and Bandar Baru Bangi) were selected in this study based on five consecutive years of high dengue cases. Entomological data were collected using ovitraps where the number of larvae was used to reflect Aedes mosquito population size; followed by RT-PCR screening to detect and serotype dengue virus in mosquitoes. Notified cases, date of disease onset, and number and type of the interventions were used as epidemiological endpoint, while rainfall, temperature, relative humidity and air pollution index (API) were indicators for environmental data. The field study was conducted during 81 weeks of data collection. Correlation and Autoregressive Distributed Lag Model were used to determine the relationship. The study showed that, notified cases were indirectly related with the environmen...
Within the last century, increases in human movement and globalization of trade have facilitated ... more Within the last century, increases in human movement and globalization of trade have facilitated the establishment of several highly invasive mosquito species in new geographic locations with concurrent major environmental, economic and health consequences. The Asian tiger mosquito, Aedes albopictus, is an extremely invasive and aggressive daytime-biting mosquito that is a major public health threat throughout its expanding range. We used 13 nuclear microsatellite loci (on 911 individuals) and mitochondrial COI sequences to gain a better understanding of the historical and contemporary movements of Ae. albopictus in the Indo-Pacific region and to characterize its population structure. Approximate Bayesian computation (ABC) was employed to test competing historical routes of invasion of Ae. albopictus within the Southeast (SE) Asian/Australasian region. Our ABC results show that Ae. albopictus was most likely introduced to New Guinea via mainland Southeast Asia, before colonizing the...
Many essential oils have been reported as natural sources of insect repellents; however, due to h... more Many essential oils have been reported as natural sources of insect repellents; however, due to high volatility, they present low repellent effect. Formulation technique by using microencapsulation enables to control the volatility of essential oil and thereby extends the duration of repellency. In this study, the effectiveness of microencapsulated essential oils of Alpinia galanga, Citrus grandis and C. aurantifolia in the lotion formulations were evaluated against mosquito bites. Essential oils and N,N-Diethyl-3-methylbenzamide (DEET) were encapsulated by using interfacial pre- cipitation techniques before incorporation into lotion base to form microencapsulated (ME) formulation. The pure essential oil and DEET were also prepared into lotion base to produce non-encapsulated (NE) formulation. All the prepared formulations were assessed for their repellent activity against Culex quinquefasciatus under laboratory condition. Field evaluations also were conducted in three different stu...
Journal of the American Mosquito Control Association, 2016
Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Ting... more Based on an ethnobotanical study on use for plant species against mosquito bites in the Kota Tinggi District, Johor State, Malaysia, 3 plants selected for study, Citrus aurantifolia (leaves), Citrus grandis (fruit peel), and Alpinia galanga (rhizome), were extracted using hydrodistillation to produce essential oils. These essential oils were then formulated as a lotion using a microencapsulation process and then tested for their repellent effect against Aedes aegypti. N,N-diethyl-m-toluamide (deet) was also prepared in the same formulation and tested for repellency as controls. Four commercial plant-based repellent (KAPS(®), MozAway(®), BioZ Natural(®), and Mosiquard(®)) also were incorporated in the bioassay for comparison purposes. Bioassays revealed that at 20% concentration all repellent formulations demonstrated complete protection for 2 h and >90% for 4 h post-application. The A. galanga-based formulation provided the greatest level of protection (98.91%), which extended fo...
ABSTRAK Ciri toksik minyak pati dari lapan belas spesies tumbuhan keatas instar keempat larva tig... more ABSTRAK Ciri toksik minyak pati dari lapan belas spesies tumbuhan keatas instar keempat larva tiga nyamuk vektor (Anopheles maculatus, Aedes aegypti dan Culex quinquejasciatus) telah dikaji. Minyak pati daripada daun Litsea elliptica adalah yang paling efektif, menunjukkan ...
To investigate the larvicidal activity, inhibition effect on development, histopathological alter... more To investigate the larvicidal activity, inhibition effect on development, histopathological alteration and morphological aberration induced by the extracts derived from seaweeds Bryopsis pennata (B. pennata), Sargassum binderi (S. binderi) and Padina australis in Aedes aegypti (Ae. aegypti) larvae and to characterize the phytochemical components of the three seaweeds. Larvicidal activity of the seaweeds towards the larvae of Ae. aegypti was determined according to WHO. The inhibition effect of seaweeds was assessed by determining the mortality, adult emergence rate, larval and pupa duration of the treated larvae. Histopathological effect on midgut epithelium of larvae and morphological aberration induced by the methanol extracts were examined. Phytochemical analysis was done to determine the presence of alkaloids, saponins, steroids and terpenoids in the seaweeds. Chloroform partition of B. pennata extract exhibited the strongest larvicidal activity (LC50 = 82.55 μg/mL), followed by methanol extract of B. pennata (LC50 = 160.07 μg/mL) and chloroform partition of S. binderi extract (LC50 = 192.43 μg/mL). The methanol extract of S. binderi exhibited the strongest effect on prolongation of larval period (1.5-fold longer as compared to control) and resulted in strongest inhibition effect in adult emergence (98.67%). The histopathological study showed that larvae treated with seaweed extracts had cytopathological alteration of the midgut epithelium. The morphological observation revealed that the anal papillae and terminal spiracles of larvae were the common sites of aberrations. The study provided information on various effects of seaweed extracts on Ae. aegypti. Further investigation on identifying the active compounds and their mechanisms of action is recommended.
Uploads
Papers