Displaying publications 261 - 280 of 337 in total

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  1. Fulltext Genotoxicity following Organophosphate Pesticides Exposure among Orang Asli Children Living in an Agricultural Island in Kuala Langat, Selangor, Malaysia
    Sutris JM, How V, Sumeri SA, Muhammad M, Sardi D, Mohd Mokhtar MT, et al.
    Int J Occup Environ Med, 2016 Jan;7(1):42-51.
    PMID: 26772597 DOI: 10.15171/ijoem.2016.705
    BACKGROUND: Agriculture is an important sector for the Malaysian economy. The use of pesticides in agriculture is crucial due to its function in keeping the crops from harmful insects. Children living near agricultural fields are at risk of pesticide poisoning.

    OBJECTIVE: To evaluate the genotoxic risk among children who exposed to pesticides and measure DNA damage due to pesticides exposure.

    METHODS: In a cross-sectional study 180 Orang Asli Mah Meri children aged between 7 and 12 years were studied. They were all living in an agricultural island in Kuala Langat, Selangor, Malaysia. The data for this study were collected via modified validated questionnaire and food frequency questionnaire, which consisted of 131 food items. 6 urinary organophosphate metabolites were used as biomarkers for pesticides exposure. For genotoxic risk or genetic damage assessment, the level of DNA damage from exfoliated buccal mucosa cells was measured using the comet assay electrophoresis method.

    RESULTS: Out of 180 respondents, 84 (46.7%) showed positive traces of organophosphate metabolites in their urine. Children with detectable urinary pesticide had a longer tail length (median 43.5; IQR 30.9 to 68.1 μm) than those with undetectable urinary pesticides (median 24.7; IQR 9.5 to 48.1 μm). There was a significant association between the extent of DNA damage and the children's age, length of residence in the area, pesticides detection, and frequency of apple consumption.

    CONCLUSION: The organophosphate genotoxicity among children is associated with the amount of exposure (detectability of urinary pesticide) and length of residence in (exposure) the study area.

    Matched MeSH terms: Insecticides/adverse effects*; Insecticides/urine
  2. Comparative field evaluation of residual-sprayed deltamethrin WG and deltamethrin WP for the control of malaria in Pahang, Malaysia
    Rohani A, Zamree I, Lim LH, Rahini H, David L, Kamilan D
    Southeast Asian J Trop Med Public Health, 2006 Nov;37(6):1139-48.
    PMID: 17333767
    The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation at 25 mg a.i./m2 and 20 mg a.i./m2 for the control of malaria was compared with the current dose of 20 mg/m2 deltamethrin wettable powder (WP) in aboriginal settlements in Kuala Lipis, Pahang, Malaysia. The malaria vector has been previously identified as Anopheles maculatus. The assessment period for the 20 mg/m2 dosage was six months, but for the 25 mg/m2 dosage, the period was 9 months. Collections of mosquitoes using the bare-leg techniques were carried out indoors and outdoors from 7:00 PM to 7:00 AM. All mosquitoes were dissected for sporozoites and parity. Larval collections were carried out at various locations to assess the extent and distribution of breeding of vectors. A high incidence of human feeds was detected during May 2005 and a low incidence during January 2005 for all the study areas. Our study showed that deltamethrin WG at 25 mg/m2 suppressed An. maculatus biting activity. More An. maculatus were caught in outdoor landing catches than indoor landing catches for all the study areas. The results indicate that 25 mg/m2 WG is good for controlling malaria for up to 9 months. Where residual spraying is envisaged, the usual two spraying cycles per year with 20 mg/m2 deltamethrin may be replaced with 25 mg/m2 deltamethrin WG every 9 months.
    Matched MeSH terms: Insecticides/administration & dosage*; Insecticides/toxicity
  3. Indirect effects of cigarette butt waste on the dengue vector Aedes aegypti (Diptera: Culicidae)
    Dieng H, Rajasaygar S, Ahmad AH, Rawi CS, Ahmad H, Satho T, et al.
    Acta Trop, 2014 Feb;130:123-30.
    PMID: 24239749 DOI: 10.1016/j.actatropica.2013.11.001
    Despite major insecticide-based vector control programs, dengue continues to be a major threat to public health in urban areas. The reasons for this failure include the emergence of insecticide resistance and the narrowing of the spectrum of efficient products. Cigarette butts (CBs), the most commonly discarded piece of waste, also represent a major health hazard to human and animal life. CBs are impregnated with thousands of chemical compounds, many of which are highly toxic and none of which has history of resistance in mosquitoes. This study was performed to examine whether exposure to CB alters various biological parameters of parents and their progeny. We examined whether the mosquito changes its ovipositional behaviors, egg hatching, reproductive capacity, longevity and fecundity in response to CB exposure at three different concentrations. Females tended to prefer microcosms containing CBs for egg deposition than those with water only. There were equivalent rates of eclosion success among larvae from eggs that matured in CB and water environments. We also observed decreased life span among adults that survived CB exposure. Extracts of CB waste have detrimental effects on the fecundity and longevity of its offspring, while being attractive to its gravid females. These results altogether indicate that CB waste indirectly affect key adult life traits of Aedes aegypti and could conceivably be developed as a novel dengue vector control strategy, referring to previously documented direct toxicity on the larval stage. But this will require further research on CB waste effects on non-target organisms including humans.
    Matched MeSH terms: Insecticides
  4. An optical biosensor for dichlovos using stacked sol-gel films containing acetylcholinesterase and a lipophilic chromoionophore
    Wong FC, Ahmad M, Heng LY, Peng LB
    Talanta, 2006 Jun 15;69(4):888-93.
    PMID: 18970653 DOI: 10.1016/j.talanta.2005.11.034
    An optical biosensor consisting of a chromoionophore (ETH5294) (CM) doped sol-gel film interfaced with another sol-gel film immobilized with acetylcholinesterase (AChE) was employed to detect the insecticide dichlorvos. The main advantage of this optical biosensor is the use of a sol-gel layer with immobilized CM that possesses lipophilic property. The highly lipophilic nature of the CM and its compatibility with the sol-gel matrix has prevented leaching, which is frequently a problem in optical sensor construction based on pH indicator dyes. The immobilization of the indicator and enzyme was simple and need no chemical modification. The CM layer is pH sensitive and detects the pH changes of the acetylcholine chloride (AChCl) substrate when hydrolyzed by AChE layer deposited above. In the absence of the AChE layer, the pH response of the CM layer is linear from pH 6 to 8 (R(2)=0.98, n=3) and it showed no leaching of the lipophilic chromoionophore. When the AChE layer is deposited on top, the optical biosensor responds to AChCl with a linear dynamic range of 40-90mM AChCl (R(2)=0.984, n=6). The response time of the biosensor is 12min. Based on the optimum incubation time of 15min, a linear calibration curve of dichlorvos against the percentage inhibition of AChE was obtained from 0.5 to 7mg/L of dichlorvos (17-85% inhibition, R(2)=0.991, n=9). The detection limit for dichlorvos was 0.5mg/L. The results of the analysis of 1.7-6.0mg/L of dichlorvos using this optical biosensor agreed well with a gas chromatography-mass spectrometry detection method.
    Matched MeSH terms: Insecticides
  5. A novel nanobiosensor for the detection of paraoxon using chitosan-embedded organophosphorus hydrolase immobilized on Au nanoparticles
    Karami R, Mohsenifar A, Mesbah Namini SM, Kamelipour N, Rahmani-Cherati T, Roodbar Shojaei T, et al.
    Prep Biochem Biotechnol, 2015 Oct 26.
    PMID: 26503886
    Organophosphorus (OP) compounds are one of the most hazardous chemicals used as insecticides/pesticide in agricultural practices. A large variety of OP compounds are hydrolyzed by organophosphorus hydrolases (OPH; EC 3.1.8.1). Therefore, OPHs are among the most suitable candidates which could be used in designing enzyme-based sensors for detecting OP compounds. In the present work, a novel nanobiosensor for the detection of paraoxon was designed and fabricated. More specifically, OPH was covalently embedded onto chitosan and the enzyme-chitosan bioconjugate was then immobilized on negatively charged gold nanoparticles (AuNPs) electrostatically. The enzyme was immobilized on AuNPs without chitosan as well to compare the two systems in terms of detection limit and enzyme stability under different pH and temperature conditions. Coumarin 1, a competitive inhibitor of the enzyme, was used as a fluorogenic probe. The emission of coumarin 1 was effectively quenched by the immobilized Au-NPs when bound to the developed nanobioconjugates. However, in the presence of paraoxon, coumarin 1 left the nanobioconjugate leading to enhanced fluorescence intensity. Moreover, compared to the immobilized enzyme without chitosan, the chitosan-immobilized enzyme was found to possess decreased Km value by over 50%, increased Vmax and Kcat values by around 15% and 74%, respectively. Higher stability within a wider range of pH (2-12) and temperature (25-90°C) was also achieved. The method worked in the 0 to 1050 nM concentration ranges, and had a detection limit as low as 5 × 10(-11) M.
    Matched MeSH terms: Insecticides
  6. The cashew nut, Anacardium occidentale (Anacardiaceae), and its perennial association with ants: extrafloral nectary location and the potential for ant defense
    Rickson F, Rickson M
    Am J Bot, 1998 Jun;85(6):835.
    PMID: 21684968
    Cashew nut trees are consistently ant-visited throughout the year, with the ants attracted to a large number of extrafloral nectaries on the leaves, inflorescences, flowers, and developing nuts. The commercial production of cashew nut, for example, in India, Brazil, and east Africa, consistently applies pesticides, especially insecticides, in large monoculture plantings. Each year prophylactic spraying begins with the first flush of new leaves, continues through flowering, ending at about mid-nut development. We surveyed for ant diversity in sprayed and unsprayed cashew monocultures of various sizes and ages in Sri Lanka, India, and Malaysia to document the ant-cashew relationship and to explore the potential of ants replacing chemical pesticides in insect control. Using for-profit, commercial-size plantations as examples, we present information that cashew has a strong potential for arthropod-dependent protection from pests and suggest important habitat considerations for encouraging ants within cashew plantings.
    Matched MeSH terms: Insecticides
  7. Fulltext Persistent mosquito fogging can be detrimental to non-target invertebrates in an urban tropical forest
    Lee NSM, Clements GR, Ting ASY, Wong ZH, Yek SH
    PeerJ, 2020;8:e10033.
    PMID: 33062440 DOI: 10.7717/peerj.10033
    Background: Human population growth has led to biodiversity declines in tropical cities. While habitat loss and fragmentation have been the main drivers of urban biodiversity loss, man-made interventions to reduce health risks have also emerged as an unintentional threat. For instance, insecticide fogging to control mosquito populations has become the most common method of preventing the expansion of mosquito-borne diseases such as Dengue. However, the effectiveness of fogging in killing mosquitoes has been called into question. One concern is the unintended effect of insecticide fogging on non-target invertebrates that are crucial for the maintenance of urban ecosystems. Here, we investigate the impacts of fogging on: (1) target invertebrate taxon (Diptera, including mosquitoes); (2) non-target invertebrate taxa; and (3) the foraging behavior of an invertebrate pollinator taxon (Lepidoptera) within an urban tropical forest.

    Methods: We carried out fogging with Pyrethroid insecticide (Detral 2.5 EC) at 10 different sites in a forest situated in the state of Selangor, Peninsular Malaysia. Across the sites, we counted the numbers of knocked-down invertebrates and identified them based on morphology to different taxa. We constructed Bayesian hierarchical Poisson regression models to investigate the effects of fogging on: (1) a target invertebrate taxon (Diptera) 3-h post-fogging; (2) selected non-target invertebrate taxa 3-h post-fogging; and (3) an invertebrate pollinator taxon (Lepidoptera) 24-h post-fogging.

    Results: A total of 1,874 invertebrates from 19 invertebrate orders were knocked down by the fogging treatment across the 10 sites. Furthermore, 72.7% of the invertebrates counted 3-h post-fogging was considered dead. Our regression models showed that given the data and prior information, the probability that fogging had a negative effect on invertebrate taxa 3-h post-fogging was 100%, with reductions to 11% of the pre-fogging count of live individuals for the target invertebrate taxon (Diptera), and between 5% and 58% of the pre-fogging count of live individuals for non-target invertebrate taxa. For the invertebrate pollinator, the probability that fogging had a negative effect 24-h post-fogging was also 100%, with reductions to 53% of the pre-fogging count of live individuals.

    Discussion: Our Bayesian models unequivocally demonstrate that fogging has detrimental effects on one pollinator order and non-target invertebrate orders, especially taxa that have comparatively lower levels of chitinisation. While fogging is effective in killing the target order (Diptera), no mosquitos were found dead in our experiment. In order to maintain urban biodiversity, we recommend that health authorities and the private sector move away from persistent insecticide fogging and to explore alternative measures to control adult mosquito populations.

    Matched MeSH terms: Insecticides
  8. Fulltext Organochlorines and organophosphates susceptibility of Aedes albopictus Skuse larvae from agricultural and non-agricultural localities in Peninsular Malaysia
    Wan-Norafikah O, Chen CD, Sofian-Azirun M
    Saudi J Biol Sci, 2021 Jan;28(1):1010-1016.
    PMID: 33424394 DOI: 10.1016/j.sjbs.2020.11.040
    Aedes albopictus larvae obtained from different types of agricultural and non-agricultural localities in Peninsular Malaysia were subjected to several larvicides at World Health Organization (WHO) recommended dosages. Upon 24 h of WHO larval bioassay using two organochlorines and six organophosphates, high resistance against dichlorodiphenyltrichloroethane (DDT), temephos, chlorpyrifos and bromophos were demonstrated among all larval populations. Aedes albopictus larvae from both paddy growing areas (92.33% mortality) and rubber estates (97.00% mortality) were moderately resistant to dieldrin while only Ae. albopictus larvae from dengue prone residential areas (89.00% mortality) showed high resistance against dieldrin. All Ae. albopictus larval populations also developed either incipient or high resistance to both malathion (33.67%-95.33% mortality) and fenitrothion (73.00%-92.67% mortality). Only Ae. albopictus larvae from fogging-free residential areas that were tolerant to fenthion (97.33% mortality), whereas Ae. albopictus larvae from dengue prone residential areas were highly resistant to the same organophosphate (88.33% mortality). Cross resistance between intraclass and interclass larvicides of organochlorines and organophosphates were also exhibited in this study. The present study provided baseline data on various susceptibility levels of Ae. albopictus larval populations from different types of agricultural and non-agricultural localities against organochlorines and organophosphates at WHO recommended dosages. Nevertheless, further susceptibility investigations are suggested using revised doses of larvicides established from the local reference strain of Ae. albopictus to prevent the underestimation or overestimation of insecticide resistance level among Ae. albopictus field strains of larvae.
    Matched MeSH terms: Insecticides
  9. Fulltext Costs of fogging activities and its contributing factors at Hulu Langat District Health Office, Selangor, Malaysia
    Muhammad Syazni, Aidalina Mahmud, Suhainizam Muhamad Saliluddin
    Malaysian Journal of Medicine and Health Sciences, 2019;15(104):107-107.
    MyJurnal
    Introduction: Dengue fever currently remains as one of the major public health issues in Malaysia. Dengue inci-dence in Malaysia has been increasing in the last 20 years. Dengue fever has been causing an economic burden to the country each year. Vector control is one of the preventions and control activities to reduce its incidence. Vector control activities, especially fogging is a resource-intensive activity. It uses most of the allocated budget of a district health office (33%). The major cost components of the prevention and control activities were human resources and pesticides with 60.7% were for human resources and 13.6% of the costs were for pesticides. Therefore, it is important to know, cost of each fogging activity and the factors that contribute to that cost. The objective of this study was to determine the costs of fogging activities carried out by Hulu Langat Health District Office, Selangor, Malaysia. Meth-ods: This study was a retrospective descriptive and analytical study using data from the Hulu Langat District Health Office for the year 2018. Cost analysis of fogging activities was carried out using the activity-based costing method-ology. The factors associated with, and predictors of, the costs of fogging activities were determined using chi-square and multiple linear regression. Results: In 2018, Hulu Langat District Health Office carried out total of 2,063 fogging activities. The average cost of each fogging activity was estimated as RM 1,579. Types of insecticides was statistically significant associated and predictive factor of the cost of fogging activity. Conclusion: The present study showed that the estimated average cost per fogging activity is RM 1,579 and water-based insecticide was found to be the cheaper option compared to oil-based insecticide. However, as this study did not determine the effectiveness of these insec-ticides, recommendations cannot be made as to which insecticide should be used.
    Matched MeSH terms: Insecticides
  10. Fulltext Mosquito larvicidal potential of tropical seaweeds: acetylcholinesterase inhibitory effects of bryopsis pennata, padina australis and sargassum binderi on Aedes aegypti (L.) and Aedes albopictus skuse
    Ke-Xin Yu, Rohani Ahmad, Ching-Lee Wong, Ibrahim Jantan
    Malaysian Journal of Medicine and Health Sciences, 2020;16(101):125-130.
    MyJurnal
    Introduction: Inhibition of the cholinesterase’s function leads to paralysis and death. This mechanism is served as a common mode of action of insecticide. The three tropical seaweeds, namely Bryopsis pennata, Padina australis and Sargassum binderi were reported for its potential mosquito larvicidal effect. In the present study, these seaweeds were evaluated for their potential as a cholinesterase inhibitor in the mechanism of larvicidal action. Methods: Ace- tylcholinsterase (AChE) inhibition assay was carried out based on the colorimetric method using a microplate reader. Phytochemical content of the seaweed extracts was screened by using liquid chromatography-mass spectroscopy (LC-MS). Results: Green seaweed B. pennata showed the strongest inhibition effect towards in vitro AChE by using
    tissue homogenates of Aedes aegypti (IC50 value = 0.84 mg mL ) and Aedes albopictus as the enzyme source (IC
    -1
    value = 0.92 mg mL-1). The pattern of Lineweaver-Burk plots revealed that B. pennata was a mixed type inhibitor of
    AChE, as the readings of Km, Vmax, Ki and Ki’, indicates that it had a strong inhibition ability with high binding affin- ity towards both free enzyme and enzyme-substrate complex. Conclusion: These findings suggest the compound(s) in
    B. pennata extract serves as a promising source that could be developed into a mosquito larvicidal agent with AChE inhibition effect.
    Matched MeSH terms: Insecticides
  11. Fulltext Entomological Surveillance on Resistance of Aedes to Aqua K-Otherine at Taman Sri Rugading, Tuaran, Sabah, Malaysia
    Netto, Marcus
    Borneo Journal of Medical Sciences, 2018;12(101):39-0.
    MyJurnal
    Dengue fever and its fatal complications have made a comeback since its control in the 1990’s. The Flavivirus has evolved into 4 serotypes DEN 1,2,3,4 which can be passed on by the mosquitoes for 7 generations for each serotype. This communicable disease is predominantly confined to urban areas. Quick control of the spread of the disease will prevent it from becoming an epidemic. The two species mosquitoes involved have different behaviours. The Aedes aegypti is an indoor vector which breeds in clean, clear and calm freshwater. The Aedes albopictus is an outdoor breeding mosquito which breeds in stagnant waters. Surveillance of the areas prone to outbreaks is vital. One of the roles of the entomologist is to monitor the vector for resistance to the insecticides. Localities that have been subjected to recurrent outbreaks will have vector which develop resistance to the insecticides used.
    Matched MeSH terms: Insecticides
  12. Fulltext Efficacy of Insecticide and Bioinsecticide Ground Sprays to Control Metisa plana Walker (Lepidoptera: Psychidae) in Oil Palm Plantations, Malaysia
    Salim H, Rawi CS, Ahmad AH, Al-Shami SA
    Trop Life Sci Res, 2015 Dec;26(2):73-83.
    PMID: 26868711 MyJurnal
    The effectiveness of the synthetic insecticides trichlorfon, lambda-cyhalothrin, cypermethrin emulsion concentrated (EC) and cypermethrin emulsion water based (EW) and a bio-insecticide, Bacillus thuringiensis subsp. kurstaki (Btk), was evaluated at 3, 7, 14 and 30 days after treatment (DAT) for the control of Metisa plana larvae in an oil palm (Elaeis guineensis) plantation in Malaysia. Although all synthetic insecticides effectively reduced the larval population of M. plana, trichlorfon, lambda-cyhalothrin and cypermethrin EC were the fastest-acting. The larval population dropped below the economic threshold level (ETL) 30 days after a single application of the synthetic insecticides. Application of Btk, however, gave poor results, with the larval population remaining above the ETL post treatment. In terms of operational productivity, ground spraying using power spray equipment was time-consuming and resulted in poor coverage. Power spraying may not be appropriate for controlling M. plana infestations in large fields. Using a power sprayer, one man could cover 2-3 ha per day. Hence, power spraying is recommended during outbreaks of infestation in areas smaller than 50 ha.
    Matched MeSH terms: Insecticides
  13. Fulltext Co-breeding Association of Aedes albopictus (Skuse) and Aedes aegypti (Linnaeus) (Diptera: Culicidae) in Relation to Location and Container Size
    Hashim NA, Ahmad AH, Talib A, Athaillah F, Krishnan KT
    Trop Life Sci Res, 2018 Mar;29(1):213-227.
    PMID: 29644025 MyJurnal DOI: 10.21315/tlsr2018.29.1.14
    The occurrence of major outbreaks of dengue, and other vector borne diseases such as chikungunya and zika in tropical and subtropical regions has rendered control of the diseases a top-priority for many affected countries including Malaysia. Control of the mosquito vectors Aedes aegypti and Aedes albopictus through the reduction of breeding sites and the application of insecticides to kill immature forms and adults are the main control efforts to combat these diseases. The present study describes the association between Ae. albopictus and Ae. aegypti in shared breeding sites. This study is important given that any measure taken against one species may affect the other. A yearlong larval survey was conducted in four dengue endemic areas of Penang Island. Sorenson's coefficient index indicated that no association between number of the immatures of the two species regardless of container size and study location. Therefore, the mean number Ae. albopictus immature was not decreased in the presence of Ae. aegypti in shared breeding container. However Ae. aegypti appeared to prefer breeding in habitats not occupied by Ae. albopictus, the two species sharing breeding sites only where available containers were limited. In control efforts, eliminating the preferred breeding containers for one species might not affect or reduce the population of the other species.
    Matched MeSH terms: Insecticides
  14. Characterization of resistance to pirimiphos-methyl (an organophosphate insecticide) in Culex pipiens pipiens (Diptera: Culicidae) from Northern and Southern Tunisia
    Tabbabi A, Daaboub J, Ben-Cheikh R, Laamari A, Feriani M, Boubaker C, et al.
    Trop Biomed, 2018 Dec 01;35(4):872-879.
    PMID: 33601837
    Despite the public health importance of Culex pipiens pipiens, their resistance to pirimiphos-methyl insecticides has not been explored enough. Late third and early fourth larvae of Culex pipiens pipiens were collected from three localities between 2003 and 2005 in Northern and Southern Tunisia. All bioassays were carried out using pirimiphosmethyl and propoxur insecticides. Populations of Culex pipiens pipiens were susceptible, moderate and resistant to pirimiphos-methyl insecticide. Resistance to this compound ranged from 2.62 in sample # 2 to 19.9 in sample # 1. The moderate resistance (5.25) was recorded in sample # 3. Synergist's tests showed that the resistance to pirimiphos-methyl was not affected by detoxification enzymes. However, biochemical assays showed the involvement of both metabolic (esterases) and target site (insensitive acetylcholinesterase) resistance mechanisms. The highest frequencies of the resistant phenotypes ([RS] and [RR]) (<0.74) were detected in the most resistant samples (#1). Four esterases enzymes including C1 encoded by the Est-1 locus and three esterases encoded by the Ester super locus: A2-B2, A4-B4 (or A5-B5, which has the same electrophoretic mobility) and B12 were detected. The highest (0.61) and the lowest (0.22) frequencies of these esterases were recorded in samples # 1 (Sidi Hcine) and # 2 (El Fahs) which recorded the highest and the lowest level of resistance, respectively. Monitoring of insecticide resistance should be evaluated regularly for management of vector control.
    Matched MeSH terms: Insecticides
  15. Multiple resistance mechanisms associated with low pirimifos-methyl resistance in Culex pipiens pipiens in three populations of Tunisia
    Tabbabi A, Daaboub J, Laamari A, Ben-Cheikh R, Feriani M, Boubaker C, et al.
    Trop Biomed, 2018 Dec 01;35(4):1107-1114.
    PMID: 33601857
    The aim of this study was to evaluate the resistance status of Culex pipiens pipiens to pirimiphos-methyl insecticide. Three field populations of mosquitoes were collected from Tunisia and analyzed in laboratory. The samples studied showed low level of resistance not exceeding 5-folds. The low resistance recorded is particularly interesting, because it leaves a range of tools useable by vector control services. Both metabolic and target-site resistance mechanisms were identified. Different esterases of high activity including A2-B2, A4-B4 (and/or A5-B5) and B12 were observed in studied field samples using starch electrophoresis although opposite results were found using synergists tests on samples # 1 and 3. The polymorphism of AChE1 (Acetylcholinesterase) was analyzed and three phenotypes were detected: susceptible (ACHE1S, phenotype [SS]), resistant (ACHE1R, phenotype [RR]), and heterozygous (phenotype [RS]) of ACHE1. The resistance of Culex pipiens pipiens to pirimiphos-methyl remains low although the occurrences of multiple resistance mechanisms are able to confer high resistance levels to organophosphate insecticides. Therefore, continuous monitoring of resistance is fundamental for rational use of insecticides and mosquito control programs.
    Matched MeSH terms: Insecticides
  16. Fulltext Pyrethroid resistance status of Aedes (Stegomyia) aegypti (Linneaus) from dengue endemic areas in Peninsular Malaysia
    Rosilawati, R., Lee, H.L., Nazni, W.A., Nurulhusna, A.H., Roziah, A., Khairul Asuad, M., et al.
    International Medical Journal Malaysia, 2017;16(2):73-78.
    MyJurnal
    Vector control is still the principal method to control dengue and chemical insecticides, especially the
    pyrethroids such as permethrin are the forerunners of mosquito control agent. Intensive and extensive use
    of pyrethroids often result in resistance, thereby hampering control efforts. The present study was
    conducted to evaluate the susceptible status of Aedes aegypti, the primary vector of dengue against
    permethrin. A nationwide mosquito sampling via ovitrapping was conducted in 12 dengue hotspots across 5
    states in Peninsular Malaysia. Field collected Aedes eggs were hatched and reared until L3 larval and further
    identified it species. Adult F0 Aedes aegypti were reared until F1 progeny and the female were used in
    adult assay, performed according to World Health Organization (WHO) protocol as to determine the
    resistance level. The laboratory strain maintained for more than 1000 generations that were susceptible to
    permethrin served as the control strain. Evaluation of resistance ratio was assessed by comparing the
    knockdown rate with laboratory susceptible strain. In this present study, 70% ofAe. aegypti population from
    dengue hotspots was highly resistance to permethrin. The study clearly demonstrated that widespread of
    permethrin resistant Ae. aegypti in Malaysian mosquito’s population, indicating the need of implementing
    an efficient pyrethroid resistance management.
    Matched MeSH terms: Insecticides
  17. Fulltext Assessment of inhibitive assay for insecticides using acetylcholinesterase from Puntius schwanenfeldii
    Mohd Khalizan Sabullah, Mohd Ezuan Khayat
    Journal of Biochemistry, Microbiology and Biotechnology, 2015;3(2):26-29.
    MyJurnal
    In this study, the substrate specificity and the inhibition kinetics of various types of insecticides to the acetylcholinesterase (AChE) from a local fish; Puntius schwanenfeldii were investigated. The substrate specificity determination was done using three thiocholine substrates, which were ATC, PTC and BTC. The results showed that he partially purified cholinesterase from Puntius schwanenfeldii that preferred ATC is a true AChE. The Km and Vmax values of AChE for these substrates were 16.61 mmol and 286.5 U/mg for ATC, 19.92 mmol and 245.3 U/mg for PTC, and 48.64 mmol and 219.6 U/mg for BTC, respectively. The IC50 values for the carbamates bendiocarb, carbaryl, propoxur, carbofuran and methomyl were 0.838, 7.045, 29.441, 1.411 and 8.335 mg/L, respectively, which were comparable to the IC50 values for carbamates from several AChE from fish.
    Matched MeSH terms: Insecticides
  18. Fulltext Screening of five plant extracts for larvicidal efficacy against larvae of Aedes aegypti (L.) and Aedes albopictus (Skuse)
    Azlinda Abu Bakar, Sallehudin Sulaiman, Baharudin Omar, Rasadah Mat Ali
    ASM Science Journal, 2018;11(2):103-116.
    MyJurnal
    The adverse effects of prolonged and rampant usage of chemical insecticides in controlling the population of vector arthropod have caused the development of resistance among vector populations as well as non-target organism. Application of plant extracts could be alternative sources for mosquito control. The present study assessed larvicidal activities of methanol extracts of leaf and stem of Jacaranda mimosifolia Don (Family: Bignoniaceae), Melaleuca cajuputi Powell (Family: Myrtaceae), Tabebuia chrysantha (Jacq.) Nicholson (Family: Bignoniaceae), Tabebuia pallida (Lindl.) Miers (Family: Bignoniaceae) and Tabebuia rosea Toll (Family: Bignoniaceae) against dengue vectors, Aedes (Diptera: Culicidae) sp. Among plants tested, M. cajuputi exhibited the most effective with the highest mortality against Ae. aegypti and Ae. albopictus. Leaf extracts showed significantly higher larvicidal effects in relative to stem extracts. The findings also revealed that Ae. aegypti is the most susceptible compared to Ae. albopictus. LC50 values of M. cajuputi leaf extracts were 183.35mg/L and 191.82mg/L against Ae. aegypti and Ae. albopictus respectively. These studies suggest leaf extracts of M. cajuputi have moderate potential as larvicidal against vector larvae of Aedes mosquitoes.
    Matched MeSH terms: Insecticides
  19. Optimization method for proteomic analysis of the larva and adult tissues of plutella xylostella (l.) (lepidoptera: plutellidae)
    Maizom Hassan, NorazilaYusoff, Wan Mohd Aizat, Idris Abd Ghani, Nurul Wahida Othman
    Sains Malaysiana, 2018;47:2975-2983.
    Plutella xylostella (L.) (Lepidoptera: Plutellidae), the major insect pest of cruciferous crops worldwide shows significant
    resistance to almost all classes of insecticides. In order to effectively prevent and manage the insecticidal resistance,
    it is crucial to understand the physiological adaptation of insects against insecticides. Identification of insect protein
    that interacting with insecticides and characterization of their modification in resistant strains can be done by using
    differential proteomics approach. This study focuses on optimizing a sensitive and rapid method for the extraction of
    high quality protein of both larva and adult tissues of P. xylostella to be used in two-dimensional gel electrophoresis.
    Five extraction methods were evaluated for protein concentration, yields and resolving patterns of one-dimensional
    and two-dimensional electrophoresis. The results showed that trichloroacetic acid/acetone extraction methods with
    two different concentrations of 2-mercaptoethanol produced the highest protein concentration and yield for both adult
    and larva tissues, respectively. Meanwhile, trichloroacetic acid/acetone with dithiothreitol extraction method gave
    better separation of spots and intensity for both larva and adult tissues compared to other methods tested. As such, we
    concluded that trichloroacetic acid/acetone with dithiothreitol successfully yielded high total protein concentration and
    good separation of two-dimensional electrophoresis gel spots in both adult and larva P. xylostella.
    Matched MeSH terms: Insecticides
  20. Fulltext Enhanced Carbofuran Degradation Using Immobilized and Free Cells of Enterobacter sp. Isolated from Soil
    Umar Mustapha M, Halimoon N, Wan Johari WL, Abd Shukor MY
    Molecules, 2020 Jun 16;25(12).
    PMID: 32560037 DOI: 10.3390/molecules25122771
    Extensive use of carbofuran insecticide harms the environment and human health. Carbofuran is an endocrine disruptor and has the highest acute toxicity to humans than all groups of carbamate pesticides used. Carbofuran is highly mobile in soil and soluble in water with a lengthy half-life (50 days). Therefore, it has the potential to contaminate groundwater and nearby water bodies after rainfall events. A bacterial strain BRC05 was isolated from agricultural soil characterized and presumptively identified as Enterobacter sp. The strain was immobilized using gellan gum as an entrapment material. The effect of different heavy metals and the ability of the immobilized cells to degrade carbofuran were compared with their free cell counterparts. The results showed a significant increase in the degradation of carbofuran by immobilized cells compared with freely suspended cells. Carbofuran was completely degraded within 9 h by immobilized cells at 50 mg/L, while it took 12 h for free cells to degrade carbofuran at the same concentration. Besides, the immobilized cells completely degraded carbofuran within 38 h at 100 mg/L. On the other hand, free cells degraded the compound in 68 h. The viability of the freely suspended cell and degradation efficiency was inhibited at a concentration greater than 100 mg/L. Whereas, the immobilized cells almost completely degraded carbofuran at 100 mg/L. At 250 mg/L concentration, the rate of degradation decreased significantly in free cells. The immobilized cells could also be reused for about nine cycles without losing their degradation activity. Hence, the gellan gum-immobilized cells of Enterobacter sp. could be potentially used in the bioremediation of carbofuran in contaminated soil.
    Matched MeSH terms: Insecticides
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