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A comparison of neurotoxicity in cerebellum produced by dermal application of chlorpyrifos in young and adult mice

Krishnan K, Mitra NK, Yee LS, Yang HM

J Neural Transm (Vienna), 2012 Mar;119(3):345-52.
PMID: 21922192 DOI: 10.1007/s00702-011-0715-5

Chlorpyrifos (CPF), an organophosphate pesticide inhibits acetylcholinesterase (AChE) and causes neuromuscular incoordination among children and elderly. The objectives of the present study were to compare the neurotoxic effects of dermal application of CPF on the cerebellum in the parameters of glial fibrillary acidic protein (GFAP) expression in young and adult mice and to correlate with the changes in acetylcholinesterase levels. Male Balb/c mice, 150 days old (adult) and 18 days old (young) were dermally applied with ½ LD(50) of CPF over the tails for 14 days. Serum AChE concentration was estimated and GFAP immunostaining was performed on sagittal paraffin sections through the vermis of cerebellum. Although reduced in both age-groups exposed to CPF, percentage of reduction in serum AChE was more in adult compared to the young. Under GFAP immunostaining, brown colour fibres and glial cells were observed in cerebellar cortex and medulla in both the experimental groups. The mean GFAP-positive glial cell count in cerebellar medulla per mm(2) of section was significantly (p

Matched MeSH terms: Insecticides/toxicity*
Genetics of spinosad resistance in a multi-resistant field-selected population of Plutella xylostella

Sayyed AH, Omar D, Wright DJ

Pest Manag Sci, 2004 Aug;60(8):827-32.
PMID: 15307676

Resistance to the bacteria-derived insecticides spinosad (Conserve), abamectin (Vertimec), Bacillus thuringiensis var kurstaki (Btk) (Dipel), B thuringiensis var aizawai (Bta) (Xentari), B thuringiensis crystal endotoxins Cry1Ac and Cry1Ca, and to the synthetic insecticide fipronil was estimated in a freshly-collected field population (CH1 strain) of Plutella xylostella (L) from the Cameron Highlands, Malaysia. Laboratory bioassays at G1 indicated significant levels of resistance to spinosad, abamectin, Cry1Ac, Btk, Cry1Ca, fipronil and Bta when compared with a laboratory insecticide-susceptible population. Logit regression analysis of F1 reciprocal crosses indicated that resistance to spinosad in the CH1 population was inherited as a co-dominant trait. At the highest dose of spinosad tested, resistance was close to completely recessive, while at the lowest dose it was incompletely dominant. A direct test of monogenic inheritance based on a back-cross of F1 progeny with CH1 suggested that resistance to spinosad was controlled by a single locus.

Matched MeSH terms: Insecticides/toxicity*
Leaching of insecticides used in blueberry production and their toxicity to red worm

Hulbert D, Raja Jamil RZ, Isaacs R, Vandervoort C, Erhardt S, Wise J

Chemosphere, 2020 Feb;241:125091.
PMID: 31683442 DOI: 10.1016/j.chemosphere.2019.125091

Soil columns were collected from a blueberry field, and insecticide solutions were allowed to leach through these columns. Insecticides from four different chemical classes were applied at two different rates: the concentration at which the insecticides wash off blueberries under rainfall conditions and the labeled field rate at which they are sprayed. The soil columns were divided into thirds; top, middle and bottom. Soil bioassays using Eisenia foetida Savigny, as an indicator species, were set up to determine the toxicity of the insecticides at a top, middle and bottom layer of the soil column. The mass of E. foetida was also measured after the bioassay experiment was completed. The concentrations at which insecticides wash-off of blueberries from rainfall were not lethal to E. foetida. In order to support mortality data, insecticide residues were quantified in the soil layers for each insecticide. Under field rate leaching conditions, carbaryl showed the high levels of toxicity in the top and middle layers of soil suggesting that it has the highest risk to organisms from leaching. This study will help blueberry growers make informed decisions about insecticide use, which can help minimize contamination of the environment.

Matched MeSH terms: Insecticides/toxicity*
Characterization of risk factors for DNA damage among paddy farm worker exposed to mixtures of organophosphates

How V, Hashim Z, Ismail P, Omar D, Said SM, Tamrin SB

Arch Environ Occup Health, 2015;70(2):102-9.
PMID: 24965330 DOI: 10.1080/19338244.2013.823905

This is a cross-sectional study conducted among paddy farmers to characterize potential risk factors that influence levels of DNA damage from exposure to mixtures of organophosphates. Comet assay was used to determine the level of DNA damage by measuring the comet tail length from the exfoliated buccal mucosa. The result suggests that farmers who chronically exposure to a mixture of organophosphates has at least 2-fold significant increase of DNA damage as compared with control group. Factor analysis and linear regression both suggest that DNA damage reported by farmers may influence individual, occupational, and residential factors and are reported as significant predictor factors, whereas this effect is mainly caused by individual factors among the control group. The findings of the present study suggest that either farmer or control group bear certain extent of genotoxic burden contributed by different risk factors.

Matched MeSH terms: Insecticides/toxicity*
Effect of concurrent application of heat, swim stress and repeated dermal application of chlorpyrifos on the hippocampal neurons in mice

Mitra NK, Nadarajah VD, Siong HH

Folia Neuropathol, 2009;47(1):60-8.
PMID: 19353435

Dermal absorption of chlorpyrifos (CPF), an organophosphate (OP) pesticide, is important because of its popular use. Stress has been reported to exacerbate neurotoxic effects of certain OP pesticides; however, quantitative studies to corroborate this are not reported. This study correlates the changes in acetylcholinesterase (AChE) levels and neuronal counts in areas of the hippocampus to consecutive exposure of stress, heat and CPF. Male mice (60 days) were segregated into six groups: one control, one stress control, and four treated groups (n=10). CPF was applied in doses of 1/2 and 1/5 of dermal LD50 (E1 and E2) over the tail of mice under occlusive bandages for 3 weeks. Stress control [(s) C] mice were subjected to swim stress at 38 degrees C (6 mins/day, 3 weeks). (s) E1 and (s) E2 were subjected to swim stress before CPF application. Blood and brain AChE levels were estimated using a spectrofluorometric method (Amplex Red). Pyramidal neurons of the cornu ammonis of the hippocampus under Nissl stain from histological sections were counted per unit area of section and analyzed statistically using one way ANOVA. Swim stress at 38 degrees C aggravated reduction of serum AChE by dermal exposure to CPF by 19.7%. Neurons of CA3 and CA1 regions of the hippocampus showed significant reduction in neuronal counts in (s) E1 and (s) E2 groups compared to E1 and E2 groups. Whereas application of CPF 1/2 dermal LD50 (E1) showed significant reduction of neuronal counts only in the CA3 area.

Matched MeSH terms: Insecticides/toxicity*
Fulltext Field bioefficacy of deltamethrin residual spraying against dengue vectors

Rozilawati H, Lee HL, Mohd Masri S, Mohd Noor I, Rosman S

Trop Biomed, 2005 Dec;22(2):143-8.
PMID: 16883280 MyJurnal

Field bioefficacy of residual-sprayed deltamethrin against Aedes vectors was evaluated in an urban residential area in Kuala Lumpur. The trial area consisted of single storey wood-brick houses and a block of flat. The houses were treated with outdoor residual spraying while the flat was used as an untreated control. Initial pre-survey using ovitrap surveillance indicated high Aedes population in the area. Deltamethrin WG was sprayed at a dosage of 25mg/m2 using a compression sprayer. The effectiveness of deltamethrin was determined by wall bioassay and ovitrap surveillance. The residual activity of 25mg/m2 deltamethrin was still effective for 6 weeks after treatment, based on biweekly bioassay results. Bioassay also indicated that both Aedes aegypti and Aedes albopictus were more susceptible on the wooden surfaces than on brick. Aedes aegypti was more susceptible than Ae. albopictus against deltamethrin. Residual spraying of deltamethrin was not very effective against Aedes in this study since the Aedes population in the study area did not reduce as indicated by the total number of larvae collected using the ovitrap (Wilcoxon Sign Test, p> 0.05). Further studies are required to improve the effectiveness of residual spraying against Aedes vectors.

Matched MeSH terms: Insecticides/toxicity
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: Insecticides/toxicity*
Investigations on feeding activity of guppy exposed to larvicides and the selective toxicities between mosquito larvae and guppy

Phurivethaya Y, Harinasuta C, Hirakoso S, Prownebon S

Med J Malaya, 1968 Mar;22(3):246.
PMID: 4234383
Matched MeSH terms: Insecticides/toxicity*
Evaluation of neurotoxicity of repeated dermal application of chlorpyrifos on hippocampus of adult mice

Mitra NK, Siong HH, Nadarajah VD

Ann Agric Environ Med, 2008;15(2):211-6.
PMID: 19061257

Dermal absorption of chlorpyrifos, an organophosphate insecticide is important because of its use in agriculture and control of household pests. The objectives of this study are to investigate firstly, the biochemical changes in the blood and secondly, histomorphometric changes in the hippocampus of adult mice following dermal application of chlorpyrifos in sub-toxic doses. Male Swiss albino mice (60 days) were segregated into one control and two treated groups (n=10). Chlorpyrifos, diluted with xylene, was applied in doses of 1/2 of LD(50) (E1) and 1/5 of LD(50) (E2) over the tail of mice of the two treated groups, 6 hours daily for 3 weeks. AChE levels in the serum and brain were estimated using a spectrophotometric method (Amplex Red reagent). Coronal serial sections were stained with 0.2 % thionin in acetate buffer and pyramidal neurons of Cornu Ammonis of hippocampus were counted at 400x magnification using Image Pro Express software. At the end of 3 weeks, body weights were reduced significantly in E1 group. Serum AChE concentrations were reduced by 97 % in E1 and 74 % in E2 groups compared to controls. The neurons of CA 3 and CA 1 in the hippocampus showed evidences of morphological damage in both treated groups. Furthermore, the neuronal count was significantly reduced in CA 3 layer of hippocampus in E1 group.

Matched MeSH terms: Insecticides/toxicity*
Fulltext Evaluation of difference in the neurotoxicity produced by dermal application of chlorpyrifos on the neonatal and adult mice

Mitra NK, Lee MS, Nadarajah VD

Trop Biomed, 2010 Apr;27(1):19-29.
PMID: 20562809

Dermal exposure to organophosphate pesticide is important because of its popular use. This study planned to compare the changes in serum acetylcholinesterase, paraoxonase and neuronal density of hippocampus and iso-cortex between two age groups of Swiss albino mice (18-day-old and 150-day-old) after dermal application of (1/2) LD50 of chlorpyrifos for 14 days. Statistically significant reduction was observed in serum acetylcholinesterase (Mann-Whitney test, p<0.05) and neuronal density (Independent samples t-test, p<0.05) in exposed groups compared to the control. The reduction in serum AChE and neuronal density was more pronounced in exposed adult mice than in exposed neonatal mice. The paraoxonase level was insignificant in control neonatal mice, whereas it was 890-fold more in exposed neonatal mice. Upregulated paraoxonase levels may be extrapolated to produce relatively lower reduction of cholinesterase and neuronal density in neonatal mice.

Matched MeSH terms: Insecticides/toxicity*
Fenitrothion alters sperm characteristics in rats: ameliorating effects of palm oil tocotrienol-rich fraction

Taib IS, Budin SB, Ghazali AR, Jayusman PA, Mohamed J

Exp Anim, 2014;63(4):383-93.
PMID: 25030881

Exposure to organophosphate insecticides such as fenitrothion (FNT) in agriculture and public health has been reported to affect sperm quality. Antioxidants may have a potential to reduce spermatotoxic effects induced by organophosphate. The present study was carried out to evaluate the effects of palm oil tocotrienol-rich fraction (TRF) in reducing the detrimental effects occurring in spermatozoa of FNT-treated rats. Adult male Sprague-Dawley rats were divided into four equal groups: a control group and groups of rats treated orally with palm oil TRF (200 mg/kg), FNT (20 mg/kg) and palm oil TRF (200 mg/kg) combined with FNT (20 mg/kg). The sperm characteristics, DNA damage, superoxide dismutase (SOD) activity, and levels of reduced glutathione (GSH), malondialdehyde (MDA), and protein carbonyl (PC) were evaluated. Supplementation with TRF attenuated the detrimental effects of FNT by significantly increasing the sperm counts, motility, and viability and decreased the abnormal sperm morphology. The SOD activity and GSH level were significantly increased, whereas the MDA and PC levels were significantly decreased in the TRF+FNT group compared with the rats receiving FNT alone. TRF significantly decreased the DNA damage in the sperm of FNT-treated rats. A significant correlation between abnormal sperm morphology and DNA damage was found in all groups. TRF showed the potential to reduce the detrimental effects occurring in spermatozoa of FNT-treated rats.

Matched MeSH terms: Insecticides/toxicity*
Fenitrothion induced oxidative stress and morphological alterations of sperm and testes in male Sprague-Dawley rats

Taib IS, Budin SB, Ghazali AR, Jayusman PA, Louis SR, Mohamed J

Clinics (Sao Paulo), 2013 Jan;68(1):93-100.
PMID: 23420164

OBJECTIVE: Fenitrothion residue is found primarily in soil, water and food products and can lead to a variety of toxic effects on the immune, hepatobiliary and hematological systems. However, the effects of fenitrothion on the male reproductive system remain unclear. This study aimed to evaluate the effects of fenitrothion on the sperm and testes of male Sprague-Dawley rats.
METHODS: A 20 mg/kg dose of fenitrothion was administered orally by gavages for 28 consecutive days. Blood sample was obtained by cardiac puncture and dissection of the testes and cauda epididymis was performed to obtain sperm. The effects of fenitrothion on the body and organ weight, biochemical and oxidative stress, sperm characteristics, histology and ultrastructural changes in the testes were evaluated.
RESULTS: Fenitrothion significantly decreased the body weight gain and weight of the epididymis compared with the control group. Fenitrothion also decreased plasma cholinesterase activity compared with the control group. Fenitrothion altered the sperm characteristics, such as sperm concentration, sperm viability and normal sperm morphology, compared with the control group. Oxidative stress markers, such as malondialdehyde, protein carbonyl, total glutathione and glutathione S-transferase, were significantly increased and superoxide dismutase activity was significantly decreased in the fenitrothion-treated group compared with the control group. The histopathological and ultrastructural examination of the testes of the fenitrothion-treated group revealed alterations corresponding with the biochemical changes compared with the control group.
CONCLUSION: A 20 mg/kg dose of fenitrothion caused deleterious effects on the sperm and testes of Sprague-Dawley rats.

Matched MeSH terms: Insecticides/toxicity*
The role of multifunctional drug therapy as an antidote to combat experimental subacute neurotoxicity induced by organophosphate pesticides

Singh S, Prakash A, Kaur S, Ming LC, Mani V, Majeed AB

Environ Toxicol, 2016 Aug;31(8):1017-26.
PMID: 25864908 DOI: 10.1002/tox.22111

Organophosphate pesticides are used in agriculture where they are associated with numerous cases of intentional and accidental misuse. These toxicants are potent inhibitors of cholinesterases leading to a massive build-up of acetylcholine which induces an array of deleterious effects, including convulsions, oxidative damage and neurobehavioral deficits. Antidotal therapies with atropine and oxime yield a remarkable survival rate, but fail to prevent neuronal damage and behavioral problems. It has been indicated that multifunction drug therapy with potassium channel openers, calcium channel antagonists and antioxidants (either single-agent therapy or combination therapy) may have the potential to prevent cell death and/or slow down the processes of secondary neuronal damage. The aim of the present study, therefore, was to make a relative assessment of the potential effects of nicorandil (2 mg/kg), clinidipine (10 mg/kg), and grape seed proanthocyanidin (GSPE) extract (200 mg/kg) individually against subacute chlorpyrifos induced toxicity. The test drugs were administered to Wistar rats 2 h after exposure to Chlorpyrifos (CPF). Different behavioral studies and biochemical estimation has been carried in the study. The results showed that chronic administration of CPF significantly impaired learning and memory, along with motor coordination, and produced a marked increase in oxidative stress along with significantly reduced acetylcholine esterase (AChE) activity. Treatment with nicorandil, clinidipine and GSPE was shown to significantly improve memory performance, attenuate oxidative damage and enhance AChE activity in rats. The present study also suggests that a combination of nicorandil, clinidipine, and GSPE has a better neuroprotective effect against subacute CPF induced neurotoxicity than if applied individually. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1017-1026, 2016.

Matched MeSH terms: Insecticides/toxicity*
Fulltext Effects of palm oil tocotrienol-rich fraction on biochemical and morphological alterations of liver in fenitrothion-treated rats

Jayusman PA, Budin SB, Ghazali AR, Taib IS, Louis SR

Pak J Pharm Sci, 2014 Nov;27(6):1873-80.
PMID: 25362611

Indiscriminate application of organophosphate (OP) pesticides has led to environmental pollution and severe health problems. The aim of the present study was to evaluate the effect of palm oil tocotrienol-rich fraction (TRF) on biochemical and morphological changes of the liver in rats treated with fenitrothion (FNT), a type of OP pesticide. A total of 28 male Sprague-Dawley rats were divided into four groups; control group, TRF-supplemented group, FNT-treated group and TRF+FNT group. TRF (200 mg/kg) was supplemented 30 minutes prior to FNT (20 mg/kg) administration, both orally for 28 consecutive days. Following 28 days of treatment, plasma biochemical changes and liver morphology were evaluated. The body and absolute liver weights were significantly elevated in TRF+FNT group compared to FNT group. TRF administration significantly decreased the total protein level and restored the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in TRF + FNT group. In contrast, total bilirubin level, γ-glutamyltranferase (GGT) and cholinesterase activity in TRF + FNT group did not significantly differ from FNT group. Administration of TRF also prevented FNT-induced morphological changes of liver as observed by electron microscope. In conclusion, TRF supplementation showed potential protective effect towards biochemical and ultrastructural changes in liver induced by FNT.

Matched MeSH terms: Insecticides/toxicity*
Selective toxicity of the mesoionic insecticide, triflumezopyrim, to rice planthoppers and beneficial arthropods

Zhu J, Li Y, Jiang H, Liu C, Lu W, Dai W, et al.

Ecotoxicology, 2018 May;27(4):411-419.
PMID: 29404868 DOI: 10.1007/s10646-018-1904-x

The novel mesoionic insecticide triflumezopyrim was highly effective in controlling both imidacloprid-susceptible and resistant planthopper populations in Malaysia. However, the toxicity of triflumezopyrim to planthopper populations and their natural enemies has been under-investigated in China. In this study, the median lethal concentrations (LC50) of triflumezopyrim were determined in eight field populations of Nilaparvata lugens and one population of Sogatella furcifera from China under laboratory conditions. Triflumezopyrim showed higher toxicity to planthopper populations than the commonly-used insecticide, imidacloprid. Furthermore, the lethal effect of triflumezopyrim on eight beneficial arthropods of planthoppers was investigated in the laboratory and compared with three commonly-used insecticides, thiamethoxam, chlorpyrifos and abamectin. Triflumezopyrim was harmless to Anagrus nilaparvatae, Cyrtorhinus lividipennis and Paederus fuscipes, while thiamethoxam, chlorpyrifos and abamectin were moderately harmful or harmful to the insect parasitoid and predators. Triflumezopyrim and thiamethoxam were harmless to the predatory spiders Pirata subpiraticus, Ummeliata insecticeps, Hylyphantes graminicola and Pardosa pseudoannulata, and slightly harmful to Theridion octomaculatum. Chlorpyrifos caused slight to high toxicity to four spider species except U. insecticeps. Abamectin was moderately to highly toxic to all five spider species. Our results indicate that triflumezopyrim has high efficacy for rice planthoppers populations and is compatibile with their natural enemies in China.

Matched MeSH terms: Insecticides/toxicity*
Efficacy of commercial household insecticide aerosol sprays against Aedes aegypti (Linn.) under simulated field conditions

Khadri MS, Kwok KL, Noor MI, Lee HL

Southeast Asian J. Trop. Med. Public Health, 2009 Nov;40(6):1226-34.
PMID: 20578457

A simulated field study on the efficacy of commercial household aerosol insecticides was conducted. The bioefficacy of three pyrethroid aerosols, designated as PA1, PA2 and PA3, was tested in cabins furnished to simulate bedroom conditions. Each aerosol product was tested against lab-bred Aedes aegypti mosquitoes based on the insecticide manufacturers' recommended dosages. Ten cages with mosquitoes were placed in the following locations: one cage in the middle of the room; two each on and underneath the bed; three each placed inside, behind and on top of the wardrobe; and four placed on and in the desk. With the desk, each cage was placed inside each of three drawers (totally closed, partially closed and opened). Prior to the experiments, the discharge rate of each aerosol can was determined. Ten to 20 lab-bred 2-5 day-old sugar-fed Ae. aegypti adult mosquitoes were placed inside the test cages. The aerosol was then discharged into the cabin at the recommended dosage. After 30 minutes, the mosquitoes were transferred into clean paper cups and their mortality recorded after 24 hours. All the aerosols induced complete or very high mortality in the caged Ae. aegypti females, except in the cages hidden completely inside the drawers and wardrobes. Insecticide droplet analysis indicated variable uniformity of the droplets was produced. The aerosol insecticides were effective against mosquitoes provided they were used in accordance with the manufacturers' recommendations.

Matched MeSH terms: Insecticides/toxicity*
Inophyllin A, a new pyranoxanthone from Calophyllum inophyllum (Guttiferae)

Ee GC, Kua AS, Lim CK, Jong V, Lee HL

Nat Prod Res, 2006 May 10;20(5):485-91.
PMID: 16644547

In the authors' continuing search for new natural products, their recent studies on the roots of Calophyllum inophyllum (Guttiferae) have yielded a new prenylated pyranoxanthone, Inophyllin A together with the common triterpenes friedelin and stigmasterol. Structural elucidations of these compounds were achieved through (1)H, (13)C, DEPT, COSY, HSQC and HMBC experiments. The molecular mass was determined using MS techniques. The authors report here the isolation of and structural elucidation for Inophyllin A as well as its toxicity test result. The discovery of this new natural product from the unexploited Malaysian forest will certainly contribute to the search for potential natural larvicides.

Matched MeSH terms: Insecticides/toxicity
Fulltext Indoor and outdoor residual spraying of a novel formulation of deltamethrin K-Othrine® (Polyzone) for the control of simian malaria in Sabah, Malaysia

Rohani A, Fakhriy HA, Suzilah I, Zurainee MN, Najdah WMAW, Ariffin MM, et al.

PLoS One, 2020;15(5):e0230860.
PMID: 32413033 DOI: 10.1371/journal.pone.0230860

Since 2000, human malaria cases in Malaysia were rapidly reduced with the use of insecticides in Indoor Residual Spray (IRS) and Long-Lasting Insecticide Net (LLIN). Unfortunately, monkey malaria in humans has shown an increase especially in Sabah and Sarawak. The insecticide currently used in IRS is deltamethrin K-Othrine® WG 250 wettable granule, targeting mosquitoes that rest and feed indoor. In Sabah, the primary vector for knowlesi malaria is An. balabacensis a species known to bite outdoor. This study evaluates an alternative method, the Outdoor Residual Spray (ORS) using a novel formulation of deltamethrin K-Othrine® (PolyZone) to examine it suitability to control knowlesi malaria vector in Sabah, compared to the current method. The study was performed at seven villages in Sabah having similar type of houses (wood, bamboo and concrete). Houses were sprayed with deltamethrin K-Othrine® (PolyZone) at two different dosages, 25 mg/m2 and 30 mg/m2 and deltamethrin K-Othrine® WG 250 wettable granule at 25 mg/m2, sprayed indoor and outdoor. Residual activity on different walls was assessed using standard cone bioassay techniques. For larval surveillances, potential breeding sites were surveyed. Larvae were collected and identified, pre and post spraying. Adult survey was done using Human Landing Catch (HLC) performed outdoor and indoor. Detection of malaria parasite in adults was conducted via microscopy and molecular methods. Deltamethrin K-Othrine® (PolyZone) showed higher efficacy when sprayed outdoor. The efficacy was found varied when sprayed on different types of wall surfaces. Deltamethrin K-Othrine® (PolyZone) at 25 mg/m2 was the most effective with regards to ability to high mortality and effective knock down (KD). The vector population was reduced significantly post-spraying and reduction in breeding sites as well. The number of simian malaria infected vector, human and simian malaria transmission were also greatly reduced.

Matched MeSH terms: Insecticides/toxicity*
Toxicity and horizontal transfer of chlorantraniliprole against the Asian subterranean termite Coptotermes gestroi (Wasmann): effects of donor:recipient ratio, exposure duration and soil type

Neoh KB, Hu J, Yeoh BH, Lee CY

Pest Manag Sci, 2012 May;68(5):749-56.
PMID: 22076820 DOI: 10.1002/ps.2322

The effectiveness of chlorantraniliprole and other insecticides (bifenthrin, fipronil, indoxacarb, imidacloprid and chlorfenapyr) were tested against Coptotermes gestroi (Wasmann). Four experiments were conducted: a topical bioassay, a horizontal transfer study, an insecticide bioavailability test and a feeding bioassay.

Matched MeSH terms: Insecticides/toxicity*
Contact toxicity and residual effects of selected insecticides against the adult Paederus fuscipes (Coleoptera: Staphylinidae)

Bong LJ, Neoh KB, Jaal Z, Lee CY

J Econ Entomol, 2013 Dec;106(6):2530-40.
PMID: 24498755

The contact toxicity of four insecticide formulations (deltamethrin, fipronil, fenitrothion, and imidacloprid) applied on three different substrates (tile, plywood, and concrete) against the adult rove beetle, Paederus fuscipes Curtis, was evaluated. The relative order of speed of killing effects was as follows: deltamethrin > imidacloprid > fipronil > fenitrothion. Although deltamethrin showed the fastest action against P. fuscipes, the recovery rate of rove beetles at 48 h posttreatment was moderate (approximately 25%) on the tile surface to high (approximately 80%) on the plywood surface. Thus, it is likely that the insects did not pick up the lethal dose especially on porous surfaces. In contrast, fipronil demonstrated delayed toxicity that might promote maximal uptake by the insects. More than 80% mortality was registered for tile and plywood surfaces up to 4 wk after exposure. High mortality (almost 100%) was recorded for imidacloprid-exposed P. fuscipes at 48 h posttreatment, but only on the tile surface. Among the four insecticides tested, fenitrothion was the least effective against P. fuscipes because low percentage to no mortality was recorded in the fenitrothion treatment.

Matched MeSH terms: Insecticides/toxicity*

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