Displaying publications 21 - 40 of 82 in total

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  1. Lee YW, Zairi J
    Trop Biomed, 2006 Jun;23(1):37-44.
    PMID: 17041550 MyJurnal
    Studies were carried out on the residual efficacy of Bacillus thuringiensis H-14 (water dispersible granule, VectoBac ABG 6511) as direct application in the control of Aedes larvae in the field. Field Aedes sp populations in the earthen and glass jars were predetermined before initiation of the trial. On confirmation of the presence of Aedes species in the designated area, Sungai Nibong Kecil, Penang Island, Malaysia, Bti was introduced in the 55L earthen and 3L glass jars). Two test designs were carried out. The first design had treated water replenished daily with 6L of seasoned water and the second design is without the replenishment of water but evaporated water was replenished. Bti was effective in the field for at least 35 days with more than 80% reduction in the Aedes larvae in the treated containers. For earthen jars with daily replenishment of water, 100% reduction was recorded for the first 3 days, while more than 80% reduction was recorded up to day 40. At day 60, Bti still provided an efficacy of 54.32 +/- 4.61 (%) of reduction. Whilst for earthen jars without daily replenishment of water, 100% reduction was recorded for the first 5 days, while more than 80% of reduction was recorded up to day 40. For the glass jars studied, similar efficacy was observed. In jars with daily replenishment of water a better larval control was observed. Percentage of reduction from day 50 to 60 for replenishment of water was between 50 to 70% compared to without replenishment of water with less than 40%.
    Matched MeSH terms: Mosquito Control/methods*
  2. Abagli AZ, Alavo TBC
    Trop Biomed, 2019 Dec 01;36(4):1003-1013.
    PMID: 33597470
    Cx. quinquefasciatus is a common nuisance mosquito widely distributed in tropical and subtropical areas. This mosquito is also a vector of urban filariasis. Control with chemicals has been hampered by the development of resistance against chemical insecticides and rising problems of environmental contamination associated with them. Therefore, it is important to adopt more integrated mosquito management approaches that include sustainable, non chemical solutions. The mermithid nematode Romanomermis iyengari is one of several natural control alternatives to synthetic pesticides for mosquito suppression. This study evaluated the effectiveness of the nematode R. iyengari for control of Cx. quinquefasciatus. The nematode R. iyengari was mass-produced, and pre-parasitics (J2) were used for laboratory and field experiments. In laboratory experiments, two concentrations of pre-parasitics (5 and 10 J2 per larva) were tested against L1, L2 and L3 instars larvae of Cx. quinquefasciatus. Infected larvae were observed daily to determine their mortality rate and the number of postparasitic nematodes emerging from dead larvae. In field experiments, 1000, 2000 and 3000 J2/m2 were sprayed in separate natural Cx. quinquefasciatus breeding sites. After treatment, the larval mosquito density in the breeding sites was assessed every 5 days. Laboratory results showed that all tested Cx. quinquefasciatus instars larvae were susceptible to nematode infection. The mortality rates observed for each larval stage indicated that the concentration of 10 J2 kills larvae faster, and that the L1 larvae died earlier than older larvae. The average number of post-parasitic nematodes emerging per larva increases with increasing nematode concentration; also more post-parasitic nematodes emerged from the L2 larvae. Field data showed that, in breeding site treated with 3000 J2 per square meter, larval mosquito reduction reached 97% after nematode application. The dosage of 1000 J2 per square meter did not reduce the larval density. The insect parasitic nematode R. iyengari could be easily used as component of integrated mosquitoes control program in lymphatic filariasis endemic countries.
    Matched MeSH terms: Mosquito Control/methods
  3. Mahmud MAF, Abdul Mutalip MH, Lodz NA, Muhammad EN, Yoep N, Hashim MH, et al.
    BMJ Open, 2019 05 15;9(5):e026101.
    PMID: 31097485 DOI: 10.1136/bmjopen-2018-026101
    INTRODUCTION: Dengue is among the most important mosquito-borne diseases, with more than half of the world's population at risk of infection in dengue endemic countries. Environmental management, which includes any activities that involve environmental modification, environmental manipulation and changes to human behaviour have been used to mitigate the risk of dengue transmission. In this protocol, we will integrate the data from various sources to assess the overall effect of environmental management on the incidence of dengue and other entomological indices.

    METHODS AND ANALYSES: We will conduct a systematic review of intervention that assess the effect of environmental management on the incidence of dengue and/or entomological indices. We will include any studies that include intervention through environmental management for dengue control, involving environmental modification, environmental manipulation and changes to human behaviour. A comprehensive search will be performed in electronic databases PUBMED, CENTRAL, SCOPUS, Web of Science and relevant research websites such as PROPSERO, WHO ICTRP and ClinicalTrials.gov to identify studies that meet our inclusion criteria. A systematic approach to searching, screening, reviewing and data extraction will be applied based on Preferred Reporting Items for Systematic reviews and Meta-Analysis. Titles, abstract, keywords for eligibility will be examined independently by researchers. The quality of the included studies will be assessed using quality assessment tool for studies with diverse design and Cochrane risk of bias tool. The characteristics of the selected articles will be described based on the study design, types of intervention and outcomes of the study in various countries. These include the types of environmental management intervention methods and the effectiveness of the intervention in reducing dengue cases or incidence and impact on entomological indices.

    ETHICS AND DISSEMINATION: We will register this systematic review with the National Medical Research Register, Ministry of Health Malaysia. This protocol also had been registered with the PROSPERO. No ethical approval is necessary, as there will be no collection of primary data. The results will be disseminated though a peer-reviewed publication and conference presentation.

    TRIAL REGISTRATION NUMBER: CRD42018092189.

    Matched MeSH terms: Mosquito Control/methods
  4. Lee HL, Khadri MS, Chiang YF
    J Vector Ecol, 1997 Dec;22(2):146-9.
    PMID: 9491365
    The combined adulticidal, larvicidal, and wall residual activity of ULV-applied bifenthrin, a synthetic pyrethroid, was evaluated in houses in Kuala Lumpur, Malaysia, against larvae and adults of lab-bred Aedes aegypti and Culex quinquefasciatus. A portable ULV sprayer was used to disperse a ULV formulation of bifenthrin at a discharge rate of 45 ml/min. The results indicated that bifenthrin sprayed at this rate exhibited all the three activities against the test mosquitoes. Complete adult mortalities were achieved, while very high larvicidal activity was also effected, which persisted for seven days. Wall bioassay with adults of Ae aegypti also resulted in very high mortality, which also persisted for one week. The combined mosquitocidal activities of bifenthrin is considered more effective especially in the control of dengue vectors.
    Matched MeSH terms: Mosquito Control/methods*
  5. Corbel V, Kont MD, Ahumada ML, Andréo L, Bayili B, Bayili K, et al.
    Parasit Vectors, 2023 Jan 20;16(1):21.
    PMID: 36670470 DOI: 10.1186/s13071-022-05554-7
    BACKGROUND: The continued spread of insecticide resistance in mosquito vectors of malaria and arboviral diseases may lead to operational failure of insecticide-based interventions if resistance is not monitored and managed efficiently. This study aimed to develop and validate a new WHO glass bottle bioassay method as an alternative to the WHO standard insecticide tube test to monitor mosquito susceptibility to new public health insecticides with particular modes of action, physical properties or both.

    METHODS: A multi-centre study involving 21 laboratories worldwide generated data on the susceptibility of seven mosquito species (Aedes aegypti, Aedes albopictus, Anopheles gambiae sensu stricto [An. gambiae s.s.], Anopheles funestus, Anopheles stephensi, Anopheles minimus and Anopheles albimanus) to seven public health insecticides in five classes, including pyrethroids (metofluthrin, prallethrin and transfluthrin), neonicotinoids (clothianidin), pyrroles (chlorfenapyr), juvenile hormone mimics (pyriproxyfen) and butenolides (flupyradifurone), in glass bottle assays. The data were analysed using a Bayesian binomial model to determine the concentration-response curves for each insecticide-species combination and to assess the within-bioassay variability in the susceptibility endpoints, namely the concentration that kills 50% and 99% of the test population (LC50 and LC99, respectively) and the concentration that inhibits oviposition of the test population by 50% and 99% (OI50 and OI99), to measure mortality and the sterilizing effect, respectively.

    RESULTS: Overall, about 200,000 mosquitoes were tested with the new bottle bioassay, and LC50/LC99 or OI50/OI99 values were determined for all insecticides. Variation was seen between laboratories in estimates for some mosquito species-insecticide combinations, while other test results were consistent. The variation was generally greater with transfluthrin and flupyradifurone than with the other compounds tested, especially against Anopheles species. Overall, the mean within-bioassay variability in mortality and oviposition inhibition were mosquito species-insecticide combinations.

    CONCLUSION: Our findings, based on the largest susceptibility dataset ever produced on mosquitoes, showed that the new WHO bottle bioassay is adequate for evaluating mosquito susceptibility to new and promising public health insecticides currently deployed for vector control. The datasets presented in this study have been used recently by the WHO to establish 17 new insecticide discriminating concentrations (DCs) for either Aedes spp. or Anopheles spp. The bottle bioassay and DCs can now be widely used to monitor baseline insecticide susceptibility of wild populations of vectors of malaria and Aedes-borne diseases worldwide.

    Matched MeSH terms: Mosquito Control/methods
  6. Lam SK
    Expert Rev Vaccines, 2013 Sep;12(9):995-1010.
    PMID: 24053394 DOI: 10.1586/14760584.2013.824712
    Dengue is a major public health concern worldwide, with the number of infections increasing globally. The illness imposes the greatest economic and human burden on developing countries that have limited resources to deal with the scale of the problem. No cure for dengue exists; treatment is limited to rehydration therapy, and with vector control strategies proving to be relatively ineffective, a vaccine is an urgent priority. Despite the numerous challenges encountered in the development of a dengue vaccine, several vaccine candidates have shown promise in clinical development and it is believed that a vaccination program would be at least as cost-effective as current vector control programs. The lead candidate vaccine is a tetravalent, live attenuated, recombinant vaccine, which is currently in Phase III clinical trials. Vaccine introduction is a complex process that requires consideration and is discussed here. This review discusses the epidemiology, burden and pathogenesis of dengue, as well as the vaccine candidates currently in clinical development.
    Matched MeSH terms: Mosquito Control/methods*
  7. Tan AW, Loke SR, Benjamin S, Lee HL, Chooi KH, Sofian-Azirun M
    PMID: 23082582
    A one year study was conducted to evaluate the impact of spray application of Bacillus thuringiensis israelensis (Bti), strain AM65-52 on vector populations and dengue transmission in a dengue endemic state in Malaysia. Residential sites with similar populations of Aedes aegypti (L.) and Aedes albopictus Skuse were studied. One site was treated with spray application of Bti into all outdoor target vector habitats, which consisted of natural and artificial containers. The other site was not treated. The impact of spray application was measured with an indoor and outdoor ovitrap index (OI) and epidemiologic data. Significant reductions in both Ae. aegypti and Ae. albopictus, OI were observed both indoors and outdoors, in treated sites compared to untreated sites (p < 0.05). OI reduction was achieved over time in the treated area. The OI was suppressed to below 10%. This was maintained for 4 weeks into the post-treatment phase. The outdoor OI at the untreated site remained at more than 40% for 38 weeks during the evaluation period. One dengue case occurred at the Bti treatment site at the beginning of the treatment phase, but no further cases were detected during the remainder of the treatment phase. However, there was an ongoing dengue outbreak in the untreated area with 15 serologically confirmed cases during weeks 37-54. Intensive fogging operations with pyrethroids at the untreated (Bti) site had a positive impact on Ae. albopictus, but not on Ae. aegypti.
    Matched MeSH terms: Mosquito Control/methods*
  8. Ahmad R, Ali WN, Nor ZM, Ismail Z, Hadi AA, Ibrahim MN, et al.
    Malar J, 2011;10:361.
    PMID: 22166101 DOI: 10.1186/1475-2875-10-361
    The application of the Geographic Information Systems (GIS) to the study of vector transmitted diseases considerably improves the management of the information obtained from the field survey and facilitates the study of the distribution patterns of the vector species.
    Matched MeSH terms: Mosquito Control/methods
  9. Cyranoski D
    Nature, 2008 May 22;453(7194):435.
    PMID: 18497781 DOI: 10.1038/453435a
    Matched MeSH terms: Mosquito Control/methods*
  10. Vythilingam I, Chan ST, Shanmugratnam C, Tanrang H, Chooi KH
    Acta Trop, 2005 Oct;96(1):24-30.
    PMID: 16076459
    A study was carried out from July 2001 until January 2003 in the Kinabatangan area of Sabah, part of Borneo island, where malaria used to be mesoendemic. Vector surveys determined that Plasmodium falciparum was the predominant species and Anopheles balabacensis the primary vector. Malaria cases have dropped drastically over the years but P. falciparum is still predominant. In the present study, Anopheles donaldi was the predominant species and was positive for sporozoites. Although An. balabacensis was present, none were infective. An. donaldi bite more outdoors than indoors and have a peak biting time from 18:00 to 19:00 h when most people are still out of their homes. An integrated malaria control programme along with area development has helped in the control of malaria and its vector.
    Matched MeSH terms: Mosquito Control/methods*
  11. Winskill P, Carvalho DO, Capurro ML, Alphey L, Donnelly CA, McKemey AR
    PLoS Negl Trop Dis, 2015 Nov;9(11):e0004156.
    PMID: 26554922 DOI: 10.1371/journal.pntd.0004156
    BACKGROUND: Aedes aegypti, the principal vector of dengue fever, have been genetically engineered for use in a sterile insect control programme. To improve our understanding of the dispersal ecology of mosquitoes and to inform appropriate release strategies of 'genetically sterile' male Aedes aegypti detailed knowledge of the dispersal ability of the released insects is needed.

    METHODOLOGY/PRINCIPAL FINDINGS: The dispersal ability of released 'genetically sterile' male Aedes aegypti at a field site in Brazil has been estimated. Dispersal kernels embedded within a generalized linear model framework were used to analyse data collected from three large scale mark release recapture studies. The methodology has been applied to previously published dispersal data to compare the dispersal ability of 'genetically sterile' male Aedes aegypti in contrasting environments. We parameterised dispersal kernels and estimated the mean distance travelled for insects in Brazil: 52.8 m (95% CI: 49.9 m, 56.8 m) and Malaysia: 58.0 m (95% CI: 51.1 m, 71.0 m).

    CONCLUSIONS/SIGNIFICANCE: Our results provide specific, detailed estimates of the dispersal characteristics of released 'genetically sterile' male Aedes aegypti in the field. The comparative analysis indicates that despite differing environments and recapture rates, key features of the insects' dispersal kernels are conserved across the two studies. The results can be used to inform both risk assessments and release programmes using 'genetically sterile' male Aedes aegypti.

    Matched MeSH terms: Mosquito Control/methods
  12. Lee HL, Singh KI
    PMID: 7526473
    A novel method for the control of Mansonia larvae was developed and tested. In this method, foliar absorption and translocation of a chemical insecticide, monocrotophos, a known systemic insecticide was studied in the Eicchornia plant. Acetone solution of the insecticide was painted onto leaves of the plant. At daily intervals, stems were severed and divided into equal sections which were introduced into bowls. Larvae of Aedes aegypti were tested for the presence of monocrotophos. It was found that translocation of the insecticide occurred at different rates in the stems and in some plants the chemical was also released into the surrounding water. Based on these results, 2 insecticides namely, monocrotophos and temephos were painted onto leaves of the host plant and their translocation to the root and water environment was examined by testing with Mansonia and Aedes aegypti larvae. The results again confirmed the translocation process and it was found that the insecticides were secreted into the surrounding water, thereby killing the larvae. However, in leaves painted with permethrin (synthetic pyrethroid) or flufenoxuron (chitin synthesis inhibitor), such a process was not detected. The potential of this new concept in Mansonia larval control is examined.
    Matched MeSH terms: Mosquito Control/methods*
  13. Bermejo A, Veeken H
    Bull World Health Organ, 1992;70(3):293-6.
    PMID: 1638658
    Insecticide-impregnated bed nets act as a physical barrier to repel and kill mosquitos. Community intervention trials suggest that these nets are effective in preventing malaria-related mortality and morbidity--but not malaria infection--in areas of low and moderate transmission; the results from areas of high transmission are not so encouraging. Comparison of the results from these trials and their interpretation are difficult because of variations in the epidemiology of malaria and several methodological flaws. Problems such as defining appropriate health indicators, monitoring bed-net usage, introducing bed nets randomly, selecting adequate controls, performing statistical analysis, and comparing bed nets with other available interventions are considered. Further community intervention trials are needed, paying attention to the methods and to assessment of their impact on malaria.
    Matched MeSH terms: Mosquito Control/methods*
  14. Vythilingam I, Chiang GL, Amatachaya C
    PMID: 1355928
    The efficacy of two formulations, wettable powder and emulsifiable concentrate, of cyfluthrin sprayed on plywood [10 mg (ai)/m2] was assessed against six species of mosquitos. The bioassay followed the WHO standard method, with some modification for the bioassay of insecticidal deposits on wall surfaces. The results indicated that these two formulations of cyfluthrin were effective against Anopheles dirus and Mansonia uniformis, moderately toxic to Aedes aegypti and Ae. albopictus in decreasing mortality through out the study period. It was least effective against Culex quinquefasciatus and An. maculatus, respectively. There was no statistically significant difference between these two formulations.
    Matched MeSH terms: Mosquito Control/methods*
  15. Hii J, Alexander N, Chuan CK, Rahman HA, Safri A, Chan M
    PMID: 8629079
    Matched MeSH terms: Mosquito Control/methods*
  16. Vythilingam I, Ridhawati, Sani RA, Singh KI
    PMID: 7909171
    The residual effectiveness of 0.005mg/ml of cyhalothrin applied to cattle was determined against three species of mosquitos: Anopheles maculatus Theobald. Anopheles dirus Peyton and Harrison Mansonia uniformis Theobald. Twenty-four hour post exposure mortality and the degree of successful blood engorgement were determined by exposing mosquitos for 10 minutes to cattle. Three replicated assays were conducted and mortality determined at 1, 2, 7, 14 and 21 days after each treatment. An initial mortality of 92-94% for An. dirus and Ma. uniformis and 79% for An. maculatus was obtained. Percentage mortality declined to 10%, 18% and 31% for An. maculatus, An. dirus and Ma. uniformis respectively on day 7 post application. On day 21 post application, percentage mortality was 2-3% for the three species of mosquitos.
    Matched MeSH terms: Mosquito Control/methods*
  17. Lim JL, Visvalingam M
    PMID: 2402678
    Two highly active synthetic pyrethroid insecticides, lambdacyhalothrin and cypermethrin, were evaluated as thermal fogs against houseflies (Musca domestica Linnaeus) and mosquitos (Aedes aegypti Linnaeus). Lambdacyhalothrin (OMS 3021) showed an average of 2.5 times more knockdown activity and over 5 times more adulticidal activity than cypermethrin against Musca domestica and Aedes aegypti. These results demonstrate that lambdacyhalothrin is highly effective at very low rates as a thermal fog against Ae. aegypti and M. domestica. Commercially available formulations of 2.5% and 5% lambdacyhalothrin can be diluted either with water for ULV cold aerosol space-spraying or with diesel/kerosene for thermal fogging at recommended application rates of 0.5-1 g ai/ha for mosquito control and 2 g ai/ha for housefly control. Due to the very low rates of application, formulated products of lambdacyhalothrin are unlikely to present any acute hazards in normal use. The low dosages required to bring about rapid control of houseflies and mosquitos make this new pyrethroid insecticide particularly cost-effective. Coupled with its good residual activity (Jutsum et al, 1984), lambdacyhalothrin can be adopted as a powerful tool in integrated pest management program for the control of medically important pests and vectors.
    Matched MeSH terms: Mosquito Control/methods*
  18. Lee HL, Seleena P
    PMID: 1948250
    A screening program searching for indigenous microbial control agents of mosquitos in Malaysia is initiated since 1987 and to date at least 20 isolates of mosquitocidal Bacillus thuringiensis serotypes have been obtained. Preliminary field evaluation of several isolates indicated that they are highly effective in the control of medically important mosquito species. For operational purposes, there is an urgent need to produce this agent utilizing cheap and locally available wastes through fermentation biotechnology. Fermentation studies in shake-flasks containing standard nutrient broth and soya bean waste, respectively, indicate that it takes about 37 hours for a Malaysian isolate of B. thuringiensis serotype H-14 to mature. In the grated coconut waste, fishmeal and rice bran, the bacteria took 28 hours, 26 hours and 126 hours respectively to mature. The endotoxin was harvested from the standard nutrient broth at 55 hours and at 50 hours from soybean, grated coconut waste and fishmeal. The endotoxin could only be harvested 150 hours after inoculation from rice bran medium. However, no bacterial growth was detected in palm oil effluent. In terms of endotoxin and biomass production, fishmeal appears to be a suitable medium. Variations in the pH of the fermenting media were also noted.
    Matched MeSH terms: Mosquito Control/methods*
  19. Lee HL, Seleena P
    PMID: 2237596
    A nationwide screening program searching for microbial control agents of mosquitos was initiated in Malaysia in 1986. A total of 725 samples were collected and 2,394 bacterial colonies were isolated and screened for larvicidal activity. From such screening, 20 Bacillus thuringiensis, 6 B. sphaericus, 1 Clostridium bifermentans and 2 Pseudomonas pseudomallei larvicidal isolates were obtained. Of these, a new B. thuringiensis named as subspecies malaysianensis was found, while the C. bifermentans was also a new anaerobe individualized as serovar malaysia. It was concluded that this screening program was highly successful.
    Matched MeSH terms: Mosquito Control/methods*
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