MyMedR

Displaying publications 1 - 20 of 92 in total

Abstract:

Sort:

Evaluation of the neurotoxic effects of chronic embryonic exposure with inorganic mercury on motor and anxiety-like responses in zebrafish (Danio rerio) larvae

Abu Bakar N, Mohd Sata NS, Ramlan NF, Wan Ibrahim WN, Zulkifli SZ, Che Abdullah CA, et al.

Neurotoxicol Teratol, 2017 Jan-Feb;59:53-61.
PMID: 27919701 DOI: 10.1016/j.ntt.2016.11.008

Chronic exposure to mercury (Hg) can lead to cumulative impairments in motor and cognitive functions including alteration in anxiety responses. Although several risk factors have been identified in recent year, little is known about the environmental factors that either due exposure toward low level of inorganic mercury that may led to the developmental disorders. The present study investigated the effects of embryonic exposure of mercury chloride on motor function and anxiety-like behavior. The embryo exposed to 6 different concentrations of HgCl2 (7.5, 15, 30, 100, 125, 250nM) at 5hpf until hatching (72hpf) in a semi-static condition. The mortality rate increased in a dose dependent manner where the chronic embryonic exposure to 100nM decreased the number of tail coiling, heartbeat, and swimming activity. Aversive stimulus was used to examine the effects of 100nM interferes with the development of anxiety-related behavior. No elevation in both thigmotaxis and avoidance response of 6dpf larvae exposed with 100nM were found. Biochemical analysis showed HgCl2 exposure affects proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. These results showed that implication of HgCl2 on locomotor and biochemical defects affects motor performance and anxiety-like responses. Yet, the potential underlying mechanisms these responses need to be further investigated which is crucial to prevent potential hazards on the developing organism due to neurotoxicant exposure.

Matched MeSH terms: Larva/drug effects*
Fulltext The toxicity of angiotensin converting enzyme inhibitors to larvae of the disease vectors Aedes aegypti and Anopheles gambiae

Abu Hasan Z', Williams H, Ismail NM, Othman H, Cozier GE, Acharya KR, et al.

Sci Rep, 2017 03 27;7:45409.
PMID: 28345667 DOI: 10.1038/srep45409

The control of mosquitoes is threatened by the appearance of insecticide resistance and therefore new control chemicals are urgently required. Here we show that inhibitors of mosquito peptidyl dipeptidase, a peptidase related to mammalian angiotensin-converting enzyme (ACE), are insecticidal to larvae of the mosquitoes, Aedes aegypti and Anopheles gambiae. ACE inhibitors (captopril, fosinopril and fosinoprilat) and two peptides (trypsin-modulating oostatic factor/TMOF and a bradykinin-potentiating peptide, BPP-12b) were all inhibitors of the larval ACE activity of both mosquitoes. Two inhibitors, captopril and fosinopril (a pro-drug ester of fosinoprilat), were tested for larvicidal activity. Within 24 h captopril had killed >90% of the early instars of both species with 3rd instars showing greater resistance. Mortality was also high within 24 h of exposure of 1st, 2nd and 3rd instars of An. gambiae to fosinopril. Fosinopril was also toxic to Ae. aegypti larvae, although the 1st instars appeared to be less susceptible to this pro-drug even after 72 h exposure. Homology models of the larval An. gambiae ACE proteins (AnoACE2 and AnoACE3) reveal structural differences compared to human ACE, suggesting that structure-based drug design offers a fruitful approach to the development of selective inhibitors of mosquito ACE enzymes as novel larvicides.

Matched MeSH terms: Larva/drug effects*
Effect of ten chlorophytes on larval survival, development and adult body size of the mosquito Aedes aegypti

Ahmad R, Chu WL, Ismail Z, Lee HL, Phang SM

Southeast Asian J. Trop. Med. Public Health, 2004 Mar;35(1):79-87.
PMID: 15272748

The effect of ten microalgal chlorophytes isolated from mosquito breeding containers on the survival, larval development and adult body size of the mosquito Aedes aegypti was investigated. All larvae fed with six of the microalgal isolates died after 7 days. These isolates were found to be resistant to digestion by mosquito larvae. Delayed pupation and body size reduction of the mosquitos fed with Chlorococcum UMACC 218 and Scenedesmus UMACC 220 were observed. In contrast, larvae fed with Ankistrodesmus convolutus UMACC 101 and Chlorococcum UMACC 213 were bigger in size than those fed with normal insectory feed. The present study showed that microalgal chlorophytes have the potential to be used as larvicidal agents for mosquitos.

Matched MeSH terms: Larva/drug effects
In vitro ovicidal and larvicidal activity of methanolic leaf extract of Manihot esculenta (cassava) on susceptible and resistant strains of Trichostrongylus colubriformis

Al-Rofaai A, Rahman WA, Sulaiman SF, Yahaya ZS

Vet Parasitol, 2012 Nov 23;190(1-2):127-35.
PMID: 22749290 DOI: 10.1016/j.vetpar.2012.05.028

This study aimed to represent the first report of the ovicidal and larvicidal activity of the methanolic leaf extract of Manihot esculenta (cassava) against eggs and larvae of susceptible and resistant strains of Trichostrongylus colubriformis. As well as, to determine the total tannin compounds, antioxidant activity and toxicity of the extract. The egg hatch test was used to evaluate ovicidal activity against unembryonated eggs, whereas larval feeding inhibition assay and MTT-formazan assay were used to evaluate larvicidal activity against first (L(1)) and infective (L(3)) larvae, respectively. The results showed no significant differences were detected between the sensitivities of susceptible and resistant strains of T. colubriformis to the extract. Eggs, L(1) and L(3) were significantly affected (P<0.001) compared with negative control, and L(1) were more sensitive than the eggs and L(3). The total tannin compounds were investigated using tannin quantification assay and determined by 254.44 TAE/mg. The antioxidant activity was evaluated using the DPPH radical scavenging assay and the median inhibition concentration (IC(50)) was determined by 2.638 mg/ml. Acute oral toxicity at dose of 5,000 mg/kg, and sub-chronic oral toxicity at 500 and 1,000 mg/kg of the extract were observed in male and female Sprague-Dawley (SD) rats. The acute oral toxicity revealed that the median lethal dose (LD(50)) of methanolic extract of cassava leaves on SD rats was greater than 5,000 mg/kg, whereas the sub-chronic oral toxicity did not show observed adverse effects at 500 and 1,000 mg/kg per day for 28 days. In conclusion, the methanolic extract of cassava leaves has direct ovicidal and larvicidal activity against T. colubriformis strains with a safety margin for animals, and it may be potentially utilized as a source of natural antioxidants.

Matched MeSH terms: Larva/drug effects
Sensitivity of two in vitro assays for evaluating plant activity against the infective stage of Haemonchus contortus strains

Al-Rofaai A, Rahman WA, Abdulghani M

Parasitol Res, 2013 Feb;112(2):893-8.
PMID: 22961237 DOI: 10.1007/s00436-012-3113-5

The sensitivity of larval paralysis assay (LPA) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide-formazan (MTT-formazan) assay was compared to evaluate the anthelmintic activity of plant extracts. In this study, the methanolic extract of Azadirachta indica (neem) was evaluated for its activity against the infective-stage larvae (L(3)) of susceptible and resistant Haemonchus contortus strains using the two aforementioned assays. In both in vitro assays, the same serial concentrations of the extract were used, and the median lethal concentrations were determined to compare the sensitivity of both assays. The results revealed a significant difference (P < 0.05) in the sensitivity of the LPA and the MTT-formazan assay. The MTT-formazan assay is more feasible for practical applications because it measured the L(3) mortality more accurately than LPA. This study may help find a suitable assay for investigating the anthelmintic activity of plant extracts against trichostrongylid nematodes.

Matched MeSH terms: Larva/drug effects
In vitro activity of neem (Azadirachta indica) and cassava (Manihot esculenta) on three pre-parasitic stages of susceptible and resistant strains of Teladorsagia (Ostertagia) circumcincta

Al-Rofaai A, Rahman WA, Sulaiman SF, Yahaya ZS

Vet Parasitol, 2012 Aug 13;188(1-2):85-92.
PMID: 22455724 DOI: 10.1016/j.vetpar.2012.03.002

Anthelmintic resistance of gastrointestinal nematodes is considered as one of the main limiting factors causing significant economic losses to the small ruminant industry. The anthelmintic properties of some plants are among the suggested alternative solutions to control these parasitic worms. The present study investigated the anthelmintic activity of neem (Azadirachta indica) and cassava (Manihot esculenta) leaf extracts against the susceptible and resistant strains of one of the most important nematodes in small ruminants, Teladorsagia (Ostertagia) circumcincta. Three different in vitro tests: egg hatch test, larval development assay, and larval paralysis assay were used to determine the efficiency of neem and cassava extracts on three pre-parasitic stages of T. circumcincta. The LC(50) was determined for the most potent extract in each plant as well as the phytochemical tests, total tannin quantification and cytotoxicity on peripheral blood mononuclear cells of goats. The results revealed a high anthelmintic activity of neem methanol extract (NME) and cassava methanol extract (CME) on both strains of T. circumcincta without significant differences between the strains. The first stage larvae were more sensitive with the lowest LC(50) at 7.15 mg/ml and 10.72 mg/ml for NME and CME, respectively, compared with 44.20mg/ml and 56.68 mg/ml on eggs and 24.91 mg/ml and 71.96 mg/ml on infective stage larvae.

Matched MeSH terms: Larva/drug effects
Morphological deformities in Chironomus spp. (Diptera: Chironomidae) larvae as a tool for impact assessment of anthropogenic and environmental stresses on three rivers in the Juru river system, Penang, Malaysia

Al-Shami S, Rawi CS, Nor SA, Ahmad AH, Ali A

Environ Entomol, 2010 Feb;39(1):210-22.
PMID: 20146859 DOI: 10.1603/EN09109

Morphological deformities in parts of the head capsule of Chironomus spp. larvae inhabiting three polluted rivers (Permatang Rawa [PRR], Pasir [PR], and Kilang Ubi [KUR]) in the Juru River Basin, northeastern peninsular Malaysia, were studied. Samples of the fourth-instar larvae at one location in each river were collected monthly from November 2007 to March 2008 and examined for deformities of the mentum, antenna, mandible, and epipharyngis. At each sample location, in situ measurements of water depth, river width, water pH, dissolved oxygen, and water temperature were made. Samples of river water and benthic sediments were also collected monthly from each larval sample location in each river and taken to the laboratory for appropriate analysis. Total suspended solids (TSSs), ammonium-N, nitrate-N, phosphate-P, chloride, sulfate, and aluminum content in water were analyzed. Total organic matter and nonresidual metals in the sediment samples were also analyzed. Among the three rivers, the highest mean deformity (47.17%) was recorded in larvae collected from KUR that received industrial discharges from surrounding garment and rubber factories, followed by PRR (33.71%) receiving primarily residues of fertilizers and pesticides from adjacent rice fields, and PR (30.34%) contaminated primarily by anthropogenic wastes from the surrounding residential areas. Among the various head capsule structures, deformity of the mentum was strongly reflective of environmental stress and amounted to 27.9, 20.87, and 30.19% in the PRR, PR, and KUR, respectively. Calculated Lenat's toxic score index satisfactorily explained the influence of prevailing environmental variables on the severity of mentum deformities. Redundancy analysis and forward selection selected TSSs, sediment Zn, Mn, Cu, and Ni, and water pH, dissolved oxygen, water temperature, total organic matter, nitrate-N, chloride, phosphate-P, ammonium-N, sulfate, and aluminum as parameters that significantly affected some proportion of deformities. The total deformities correlated closely with deformities of mentum but only weakly with deformities in other parts of head. The total deformity incidence was strongly correlated with high contents of sediment Mn and Ni. The mentum and epipharyngis deformities incidence was highly correlated with an increase of TSSs, total aluminum, and ammonium-N and a decrease in pH and dissolved oxygen.

Matched MeSH terms: Larva/drug effects
Genotoxicity of heavy metals to the larvae of Chironomus kiiensis Tokunaga after short-term exposure

Al-Shami SA, Rawi CS, Ahmad AH, Nor SA

Toxicol Ind Health, 2012 Sep;28(8):734-9.
PMID: 22025505 DOI: 10.1177/0748233711422729

The genotoxic effects of increasing concentrations (below lethal concentration [LC₅₀]) of cadmium ([Cd] 0.1, 1 and 10 mg/L), copper ([Cu] 0.2, 2 and 20 mg/L) and zinc ([Zn] 0.5, 5 and 50 mg/L) on Chironomus kiiensis were evaluated using alkaline comet assay after exposure for 24 h. Both the tail moment and the olive tail moment showed significant differences between the control and different concentrations of Cd, Cu and Zn (Kruskal-Wallis, p < 0.05). The highest concentration of Cd was associated with higher DNA damage to C. kiiensis larvae compared with Cu and Zn. The potential genotoxicity of these metals to C. kiiensis was Cd > Cu > Zn.

Matched MeSH terms: Larva/drug effects*
Evaluation of mentum deformities of Chironomus spp. (Chironomidae: Diptera) larvae using modified toxic score index (MTSI) to assess the environmental stress in Juru River Basin, Penang, Malaysia

Al-Shami SA, Salmah MR, Hassan AA, Azizah MN

Environ Monit Assess, 2011 Jun;177(1-4):233-44.
PMID: 20697808 DOI: 10.1007/s10661-010-1630-1

Morphological mentum deformities which represent sublethal effect of exposure to different types of pollutants were evaluated in Chironomus spp. larvae inhabiting three polluted rivers of Juru River Basin in northwestern peninsular Malaysia. Using mentum deformity incidences, the modified toxic score index (MTSI) was developed based on Lenat's toxic score index (TSI). The suggested MTSI was compared with TSI in terms of its effectiveness to identify different pollutants including heavy metals. The MTSI showed stronger relationship to total deformity incidence expressed as percentage. Additionally, the multivariate RDA model showed higher capability of MTSI to explain the variations in heavy metal contents of the river sediments. The MTSI was recommended in bioassessment of water and sediment quality using the mentum deformities of Chironomus spp. larvae from aquatic ecosystems receiving anthropogenic, agricultural, or industrial discharges.

Matched MeSH terms: Larva/drug effects
Fulltext The impact of different plant extracts on population suppression of Helicoverpa armigera (Hub.) and tomato (Lycopersicon esculentum Mill) yield under field conditions

Ali S, Li Y, Haq IU, Abbas W, Shabbir MZ, Khan MM, et al.

PLoS One, 2021;16(12):e0260470.
PMID: 34852006 DOI: 10.1371/journal.pone.0260470

Helicoverpa armigera (Hub.) is a destructive pest of the tomato (Lycopersicon esculentum Mill) crop in Pakistan. Although insecticides are the primary management strategy used to control H. armigera, most of them are not effective due to considerable toxic residual effects on the fruits. Nonetheless, H. armigera is rapidly evolving resistance against the available pesticides for its management. This situation calls upon the need of alternative management options against the pest. Different plant extracts have been suggested as a viable, environment-friendly option for plant protection with minimal side effects. Furthermore, the plant extracts could also manage the insect species evolving resistance against pesticides. This study evaluated the efficacy of different plant extracts (i.e., Neem seed, turmeric, garlic and marsh pepper) against H. armigera. Furthermore, the impact of the plant extracts on growth and yield of tomato crop was also tested under field conditions. The results revealed that all plant extracts resulted in higher mortality of H. armigera compared to control. Similarly, the highest plant height was observed for the plants treated with the plant extracts compared to untreated plants. Moreover, the highest tomato yield was observed in plants treated with plant extracts, especially with neem seed (21.013 kg/plot) followed by pepper extract (19.25 kg/plot), and garlic extract 18.4 kg/plot) compared to the untreated plants (8.9 kg/plot). It is concluded that plant extracts can be used as eco-friendly approaches for improving tomato yield and resistance management of H. armigera.

Matched MeSH terms: Larva/drug effects*
Fulltext Eco-friendly synthesis of silver nanoparticles and its larvicidal property against fourth instar larvae of Aedes aegypti

Ali ZA, Roslan MA, Yahya R, Wan Sulaiman WY, Puteh R

IET Nanobiotechnol, 2017 Mar;11(2):152-156.
PMID: 28476997 DOI: 10.1049/iet-nbt.2015.0123

In this study, larvicidal activity of silver nanoparticles (AgNPs) synthesised using apple extract against fourth instar larvae of Aedes aegypti was determined. As a result, the AgNPs showed moderate larvicidal effects against Ae. aegypti larvae (LC50 = 15.76 ppm and LC90 = 27.7 ppm). In addition, comparison of larvicidal activity performance of AgNPs at high concentration prepared using two different methods showed that Ae. aegypti larvae was fully eliminated within the duration of 2.5 h. From X-ray diffraction, the AgNP crystallites were found to exhibit face centred cubic structure. The average size of these AgNPs as estimated by particle size distribution was in the range of 50-120 nm. The absorption maxima of the synthesised Ag showed characteristic Ag surface plasmon resonance peak. This green synthesis provides an economic, eco-friendly and clean synthesis route to Ag.

Matched MeSH terms: Larva/drug effects*
Green-synthesised nanoparticles from Melia azedarach seeds and the cyclopoid crustacean Cyclops vernalis: an eco-friendly route to control the malaria vector Anopheles stephensi?

Anbu P, Murugan K, Madhiyazhagan P, Dinesh D, Subramaniam J, Panneerselvam C, et al.

Nat Prod Res, 2016 Sep;30(18):2077-84.
PMID: 26679526 DOI: 10.1080/14786419.2015.1114935

The impact of green-synthesised mosquitocidal nanoparticles on non-target aquatic predators is poorly studied. In this research, we proposed a single-step method to synthesise silver nanoparticles (Ag NP) using the seed extract of Melia azedarach. Ag NP were characterised using a variety of biophysical methods, including UV-vis spectrophotometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. In laboratory assays on Anopheles stephensi, Ag NP showed LC50 ranging from 2.897 (I instar larvae) to 14.548 ppm (pupae). In the field, the application of Ag NP (10 × LC50) lead to complete elimination of larval populations after 72 h. The application of Ag NP in the aquatic environment did not show negative adverse effects on predatory efficiency of the mosquito natural enemy Cyclops vernalis. Overall, this study highlights the concrete possibility to employ M. azedarach-synthesised Ag NP on young instars of malaria vectors.

Matched MeSH terms: Larva/drug effects
Efficacy of agnique (mmf) monomolecular surface film against immature stages of Anopheles arabiensis patton and Culex spp (diptera: culicidae) in Khartoum, Sudan

Bashir A, Hassan AA, Salmah MR, Rahman WA

Southeast Asian J. Trop. Med. Public Health, 2008 Mar;39(2):222-8.
PMID: 18564706

The efficacy of the larvicidal and pupicidal agent (Agnique) MMF was evaluated against larvae of An. arabiensis and Culex (Diptera: Culicidae) under field conditions in Bahary Locality, Khartoum, Sudan. At an applied dosage of 0.25 ml/m2, MMF resulted in 89.4, 79.8 and 88.2% reductions in L3-L4 instars An. arabiensis and 63.5% in Culex larvae (all stages) 24 to 72 hours post-treatment. Pupae were completely eliminated (100%) within 24 hours posttreatment. The earlier instars (L1-L2) of An. arabiensis were more tolerant with a 62.5% reduction at 72 hours post-treatment compared to (L3-L4) instars and pupae. At 7-days post-treatment Agnique gave a 57.5% reduction in L1-L2 and 92.6% in L3-L4 instar larvae of An. arabiensis and 57.3% and 86.4% in Culex larvae and pupae, respectively. We conclude that Agnique can perform effectively against L3-L4 instars and pupae of An. arabiensis for only 1 week, and 3 to 4 days against L1-L2 instars of Culex spp.

Matched MeSH terms: Larva/drug effects
Fulltext Analysis of chemical compositions and larvicidal activity of nut extracts from Areca catechu Linn against Aedes (Diptera: Culicidae)

Bharathithasan M, Ravindran DR, Rajendran D, Chun SK, Abbas SA, Sugathan S, et al.

PLoS One, 2021;16(11):e0260281.
PMID: 34843539 DOI: 10.1371/journal.pone.0260281

BACKGROUND: There is a growing need to use green alternative larvicidal control for Aedes larvae compared to chemical insecticides. Substantial reliance on chemical insecticides caused insecticide resistance in mosquito populations. Thus, research for alternate chemical compounds from natural products is necessary to control Aedes larvae. This study explores the analysis of chemical compositions from Areca catechu nut as a potential larvicide for Aedes (Diptera: Culicidae).
METHODS: The Areca catechu nut collected from Ipoh, Perak, Malaysia was grounded into powder and used for Soxhlet extraction. The chemical analysis of the extracts and their structures were identified using the GCMS-QP2010 Ultra (Shimadzu) system. National Institute of Standards and Technology (NIST) Chemistry WebBook, Standard Reference Database 69 (https://webbook.nist.gov/chemistry/) and PubChem (https://pubchem.ncbi.nlm.nih.gov/), the two databases used to retrieve the synonyms, molecular formula, molecular weight, and 2-dimensional (2D) structure of chemical compounds. Next, following WHO procedures for larval bioassays, the extracts were used to asses larvicidal activity against early 4th instar larvae of Aedes aegypti and Aedes albopictus.
RESULTS: The larvicidal activities were observed against early 4th stage larvae with different concentrations in the range from 200 mg/L to 1600 mg/L. The LC50 and LC95 of Aedes aegypti were 621 mg/L and 2264 mg/L respectively; whereas the LC50 and LC95 of Aedes albopictus were 636 mg/L and 2268 mg/L respectively. Mortality was not observed in the non-target organism test. The analysis using gas chromatography and mass spectrometer recovered several chemical compounds such as Arecaidine, Dodecanoic acid, Methyl tetradecanoate, Tetradecanoic acid , and n-Hexadecanoic acid bioactive components. These chemical constituents were used as additive formulations in pesticides, pest control, insect repellent, and insecticidal agents.
CONCLUSIONS: Our study showed significant outcomes from the extract of Areca catechu nut and it deserves further investigation in relation to chemical components and larvicidal actions between different species of Aedes mosquitoes. Even though all these findings are fundamental, it may have some interesting potentials to be developed as natural bio-larvicidal products.

Matched MeSH terms: Larva/drug effects
Permethrin resistance in Aedes albopictus (Diptera: Culicidae) and associated fitness costs

Chan HH, Zairi J

J Med Entomol, 2013 Mar;50(2):362-70.
PMID: 23540125

Insecticide resistance has become a serious issue in vector management programs. Information on insecticidal resistance and its associated mechanisms is important for successful insecticide resistance management. The selection of a colony of permethrin-resistant Aedes albopictus (Skuse) (Diptera: Culicidae), originating from Penang Island, Malaysia, yielded high larval-specific resistance to permethrin and cross-resistance to deltamethrin. Synergism assays showed that the major mechanism underlying this resistance involves cytochrome P450 monooxygenase. The resistance is autosomal, polygenically inherited and incompletely dominant (D = 0.26). Resistant larvae were reared under different conditions to assess the fitness costs. Under high larval density, larval development time of the resistant SGI strain was significantly longer than the susceptible VCRU strain. In both high- and low-density conditions SGI showed a lower rate of emergence and survival compared with the VCRU strain. Resistant larvae were more susceptible to predation by Toxorhynchites splendens (Wiedemann) (Diptera: Culicidae) larvae. The body size of SGI females reared under high-density conditions was larger compared with females of the susceptible strain. SGI females survived longer when starved than did VCRU females. The energy reserve upon eclosion was positively correlated with the size of the adults.

Matched MeSH terms: Larva/drug effects
Fulltext Temephos resistance in field Aedes (Stegomyia) albopictus (Skuse) from Selangor, Malaysia

Chen CD, Nazni WA, Lee HL, Norma-Rashid Y, Lardizabal ML, Sofian-Azirun M

Trop Biomed, 2013 Jun;30(2):220-30.
PMID: 23959487 MyJurnal

Larvae of Aedes albopictus obtained from dengue endemic areas in Selangor, Malaysia were evaluated for their susceptibility to operational dosage of temephos (1 mg/L). Larval bioassays were carried out in accordance to modified WHO standard methods. Biochemical microassay of enzymes in Ae. albopictus was conducted to detect the emergence of insecticide resistance and to define the mechanisms involved in temephos resistance. The 50% mortality lethal time (LT50) for Ae. albopictus tested against temephos ranged between 58.65 to 112.50 minutes, with resistance ratio ranging from 0.75 - 1.45. This study addressed the fluctuation of time-related susceptibility status of Ae. albopictus towards insecticide. Significant difference on the weekly enzyme levels of non-specific esterases, mixed function oxidases and glutathione S-transferases was detected (p ≤ 0.05). No significant correlation was found between temephos resistance and enzyme activity (p > 0.05). Only glutathione S-transferases displayed high level of activity, indicating that Ae. albopictus may be resistant to other groups of insecticide. The insensitive acetylcholinesterase was detected in some field collected Ae. albopictus populations, indicating the possibility of emergence of carbamate or other organophosphate resistance in the field populations. Continuous resistance monitoring should be conducted regularly to confirm the efficacy of insecticides for dengue control.

Matched MeSH terms: Larva/drug effects
Fulltext Field evaluation of the bioefficacy of diflubenzuron (Dimilin) against container-breeding Aedes sp. mosquitoes

Chen CD, Seleena B, Chiang YF, Lee HL

Trop Biomed, 2008 Apr;25(1):80-6.
PMID: 18600208

The inhibitory activity of diflubenzuron, a chitin synthesis inhibitor, on the ecdysis of Aedes sp. larvae was evaluated in earthen jars and automobile tires. Two formulations of diflubenzuron were used in this study: Dimilin(R) WP (wettable powder), 25% and Dimilin GR (granular), 2%. The equivalent rate of 25 g/ha, 50 g/ha and 100 g/ha active ingredients for both WP and GR formulations were used in this study. Generally, at the higher dosage of 100 g/ha, both formulations were more effective against Aedes mosquitoes. On the whole, the WP formulation appeared to perform better than the GR formulation in terms of residual activity.

Matched MeSH terms: Larva/drug effects
Fulltext Susceptibility of Aedes aegypti and Aedes albopictus to temephos in four study sites in Kuala Lumpur City Center and Selangor State, Malaysia

Chen CD, Nazni WA, Lee HL, Sofian-Azirun M

Trop Biomed, 2005 Dec;22(2):207-16.
PMID: 16883289 MyJurnal

Larvae obtained from Taman Samudera (Gombak, Selangor), Kampung Banjar (Gombak, Selangor), Taman Lembah Maju (Cheras, Kuala Lumpur) and Kampung Baru (City centre, Kuala Lumpur) were bioassayed with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos. All strains of Aedes aegypti and Aedes albopictus showed percentage mortality in the range of 16.00 to 59.05 and 6.4 to 59.50 respectively, after 24 hours. LT50 values for the 6 strains of Ae. aegypti and Ae. albopictus were between 41.25 to 54.42 minutes and 52.67 to 141.76 minutes respectively, and the resistance ratio for both Aedes species were in the range of 0.68 to 1.82 when tested with operational dosage, 1 mg/L temephos. These results indicate that Aedes mosquitoes have developed some degree of resistance. However, complete mortality for all strains were achieved after 24 hours when tested against 1 mg/L temephos.

Matched MeSH terms: Larva/drug effects
Fulltext Weekly variation on susceptibility status of Aedes mosquitoes against temephos in Selangor, Malaysia

Chen CD, Nazni WA, Lee HL, Sofian-Azirun M

Trop Biomed, 2005 Dec;22(2):195-206.
PMID: 16883288 MyJurnal

Larvae of Aedes aegypti and Aedes albopictus obtained from 6 consecutive ovitrap surveillance (OS) in Taman Samudera and Kg. Banjar were evaluated for their susceptibility to temephos. Larval bioassays were carried out in accordance with WHO standard methods, with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) of temephos respectively. Aedes aegypti and Ae. albopictus obtained from six OS in Taman Samudera showed resistance to diagnostic dosage of temephos with percentage mortality between 5.3 to 72.0 and 9.3 to 56.0, respectively, while Ae. aegypti and Ae. albopictus obtained from Kg. Banjar showed resistance to temephos with percentage mortality between 16.0 to 72.0 and 0 to 50.6, respectively. Only two strains of Ae. aegypti from Kg. Banjar were susceptible to temephos with 93.3% (OS 2) and 100% (OS 3) mortality. The 50% mortality at lethal time (LT50) for all strains of Ae. aegypti and Ae. albopictus tested against operational dosage of temephos showed range between 36.07 to 75.69 minutes and 58.65 to 112.50 minutes, respectively, and complete mortality was achieved after 24 hours. Our results indicated that there is weekly variations of the resistance status for Ae. aegypti and Ae. albopictus. Aedes susceptibility to temephos is changing from time to time in these two study sites. It is essential to continue monitoring the resistance of this vector to insecticides in order to ensure the efficiency of program aimed at vector control and protection of human health.

Matched MeSH terms: Larva/drug effects
Fulltext Laboratory bioefficacy of CREEK 1.0G (temephos) against Aedes (Stegomyia) aegypti (Linnaeus) larvae

Chen CD, Lee HL

Trop Biomed, 2006 Dec;23(2):220-3.
PMID: 17322825 MyJurnal

The bioefficacy of a commercial formulation of temephos, Creek against Aedes aegypti larvae was studied in the laboratory. Earthen jars were filled with 10 L tap water each. One g of temephos (Creek) sand granule formulation was added into each earthen jar as recommended by the manufacturer. The final test concentration of Creek was 1 mg a.i./L. One earthen jar was filled with 10 L tap water and served as a test control (untreated). Thirty late 3(rd) or early 4(th) instar of lab-bred Ae. aegypti larvae were added into each earthen jar. Mortality of the larvae was recorded after 24 hours and percent mortality was calculated. Test was repeated every week. The results showed that complete larval mortality was achieved after 24 hours. The residual effect lasted 15 weeks (105 days), indicating that Creek is effective at the dosage recommended by the manufacturer which is 1 mg a.i./L.

Matched MeSH terms: Larva/drug effects

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links