Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INSECTICIDES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,513 records · Page 84Linked to original sources
PubMed2006

Use of insecticide-treated clothes for personal protection against malaria: a community trial.

BACKGROUND: The study sought to determine the effect of using insecticide-treated clothes (ITCs) on personal protection against malaria infection. The specific objectives were to determine the effect of using ITCs on the rate of infection with malaria parasites and the effect on indoor mosquito density. METHODS: This study was done in Dadaab refugee camps, North Eastern Province Kenya between April and August 2002, and involved a total of 198 participants, all refugees of Somali origin. The participants were selected through multi-stage cluster sampling. Half of the participants (treatment group) had their personal clothes worn on a daily basis (Diras, Saris, Jalbaabs, Ma'awis and shirts) and their bedding (sheets and blankets) treated with insecticide (permethrin). The other half (comparison group) had their clothes treated with placebo (plain water). Indoor mosquito density was determined from twelve households belonging to the participants; six in the treatment block and six in the comparison block. During pre-test and post-test, laboratory analysis of blood samples was done, indoor mosquito density determined and questionnaires administered. Using STATA statistical package, tests for significant difference between the two groups were conducted. RESULTS: Use of ITCs reduced both malaria infection rates and indoor mosquito density significantly. The odds of malaria infection in the intervention group were reduced by about 70 percent. The idea of using ITCs for malaria infection control was easily accepted among the refugees and they considered it beneficial. No side effects related to use of the ITCs were observed from the participants. CONCLUSION: The use of ITCs reduces malaria infection rate and has potential as an appropriate method of malaria control. It is recommended, therefore, that this strategy be considered for use among poor communities like slum dwellers and other underprivileged communities, such as street children and refugees, especially during an influx to malaria-prone regions. Further research on cost-effectiveness and sustainability of this strategy is worthwhile.

Adolescent↗
PubMed1992

Patch-clamp analysis of the effects of the insecticide deltamethrin on insect neurones.

1. The mode of action of the pyrethroid insecticide deltamethrin on inexcitable embryonic cultured cockroach neurones has been investigated using the patch-clamp technique. 2. Whole-cell recordings of the current induced by step depolarizations of the cell membrane showed that concentrations of deltamethrin ranging from 10(-8) to 5 x 10(-6) mol l-1 induced a small tetrodotoxin (TTX)-sensitive inward current that peaked at around +10 mV and reversed at around +60 mV. The activation and inactivation kinetics of this current were much slower than those of the axonal sodium current in this same species and were relatively insensitive to membrane potential. Steady-state inactivation was almost absent. 3. Single-channel activity associated with the action of the insecticide was analyzed using the cell-attached configuration. Three distinct patterns of activity were found: (1) discrete single-channel events of relatively short duration, (2) long events of comparatively small amplitude and (3) complex bursts made up of a succession of openings and closings to several levels. These three patterns were analyzed quantitatively using specially designed programs. 4. The first pattern of activity could be seen in most patches. It consisted of short (1-10 ms) rectangular events of comparatively small amplitude (1.5 pA at rest) and very low open time probability (around 0.001). The current-voltage relationship of these small events was linear over the voltage range studied and the (extrapolated) reversal potential approximated ENa. 5. The second pattern of activity was observed less frequently. The channels could stay open for very long periods (up to several seconds) and occasionally flickered between two or more levels. 6. The third pattern of activity was observed in many patches. During the burst, which could last from a few milliseconds to a few hundred milliseconds, the single-channel current jumped almost continuously between several levels (up to 7 or 8).

Animals↗
PubMed1994

Analyses of metal ions in spider venoms in relation to insecticidal activity of clavamine.

To elucidate insecticidal activity of spider toxins, metal ions in venoms and in the bodies were determined by thin layer chromatography, spark source mass spectrometry, ion chromatography, inductively coupled plasma emission spectrometry and atomic absorption spectrometry. Two kinds of spiders were used, Nephila clavata and Nephila maculata. Metals from their venom glands were extracted with hydrochloric acid and the metal concentrations were almost the same in the two species. Many kinds of metals, Fe, Zn, Pb, Cu, Ca, Mg, Na, P and S were found at higher levels in the venoms at concentrations higher than in the bodies. The contents of metal ions were low in the dragonfly and the cicada which are considered to be preys. Clavamine, the main insecticidal component in N. clavata, was effective on larvae of a mosquito with Ca2+, Fe3+ or Pb2+, but ineffective with Mg2+, Zn2+, Fe2+ or Cu2+. It is suggested that the metal chelates play an important role in the intoxication and detoxication of the spider toxins.

Animals↗
PubMed1998

Identification of Bombyx mori midgut receptor for Bacillus thuringiensis insecticidal CryIA(a) toxin.

As part of a study of the mechanism by which Bacillus thuringiensis insecticidal crystal protein acts, a Bombyx mori receptor to the CryIA(a) toxin specific for lepidopterans was examined. Histological examination showed that the toxin acted on the brush-border membrane of the midgut columnar cells and broke its infolding structure, causing cell lysis. The membrane vesicles were purified, and a 175-kDa protein binding the toxin was found that accounted for some 0.015% of membrane proteins. The protein, designated BtR175, was a glycoprotein that reacted with concanavalin A. Anti-BtR antibodies inhibited the binding of toxin to membrane vesicles in vitro and decreased the effect of the toxin to silkworms in vivo. BtR175, although found in the gut, was not found in fat bodies, integument, or silk glands. These results indicated that BtR175 was the receptor protein for the insecticidal toxin. Proteins (137 and 107 kDa) binding the CryIA(a) toxin also were found in the gut membranes of Tenebrio moritor larvae, a coleopteran not sensitive to the toxin. The specificity of the toxin could not be explained only in term of the existence of its binding protein.

Animals↗
PubMed2000

New insecticidal bufadienolide, bryophyllin C, from Kalanchoe pinnata.

Two insecticidal bufadienolides (1 and 2) were isolated from a methanol extract of the leaves of Kalanchoe pinnata by bioassay-guided fractionation. Compound 1 was identified as known bryophyllin A (bryotoxin C). The structure of new bufadienolide 2, named bryophyllin C, was determined by spectroscopic methods and the chemical transformation of 1. Compounds 1 and 2 showed strong insecticidal activity against third instar larvae of the silkworm (Bombyx mori), their LD50 values being evaluated as 3 and 5 microg/g of diet, respectively.

Animals↗
PubMed2000

Effect of the azetidine and azocine rings of okaramine B on insecticidal activity.

Four degraded okaramine B (2) products, 4',5'-dihydrookaramine B (3), two azetidine ring-opened compounds (4 and 5) and 1',2',4',5'-tetrahydrookaramine B (6), were prepared and their insecticidal activity was examined. Neither compounds 4 nor 5 showed such activity against silkworms, indicating that the azetidine ring moiety played an important role in the insecticidal activity. Moreover, both compounds 3 and 6 exhibited lower activity than 2, which means that the azocine ring moiety was indispensable to form the active conformation.

Alkaloids↗
PubMed2002

Synthesis and insecticidal activity of N-oxydihydropyrroles: 4-hydroxy-3-mesityl-5,5-dimethyl derivatives with various substituents at the 1-position.

A new series of N-oxydihydropyrrole derivatives was synthesized and evaluated for insecticidal activity against Nilaparvata lugens and Myzus persicae. Various substituents were introduced to the 1-position of the dihydropyrrole ring, and the derivatives obtained exhibited systemic and/or contact insecticidal activity. The structure-activity relationship revealed that small alkyoxy and alkoxyalkoxy groups were more favorable than alkylcarbonyloxy, alkoxycarbonyloxy, or sulfonyloxy groups as substituents at the 1-position.

Animals↗
PubMed2003

Asymmetric chloronicotinyl insecticide, 1-[1-(6-chloro-3-pyridyl)ethyl]-2-nitroiminoimidazolidine: preparation, resolution and biological activities toward insects and their nerve preparations.

The asymmetric chloronicotinyl insecticide, 1-[1-(6-chloro-3-pyridyl)ethyl]-2-nitroiminoimidazolidine, was prepared, and the absolute configurations of the enantiomers were determined by an X-ray analysis. The insecticidal activity against the housefly measured with metabolic inhibitors showed the (S) enantiomer to be slightly more active than the (R) isomer. Electrophysiological measurements on the American cockroach central nerve cord showed the compounds to elicite the impulses and subsequently blocked them. The neuroblocking potency of the (S) isomer was 5.9 microM, while that of the (R) isomer was as high as 73 microM. The molar concentrations required for 50% inhibition of the specific binding of [3H]imidacloprid to the housefly head membrane preparation were respectively 0.19 microM and 0.95 microM for the (S) and (R) isomers. This enatioselectivity ratio was smaller than 35 for nicotine isomers but greater than 2 for epibatidine isomers.

Animals↗
PubMed2001

Metabolites of pyrethroid insecticides in urine specimens: current exposure in an urban population in Germany.

Pyrethroids are important insecticides used in agriculture, forestry, horticulture, and in the home. In humans, they are rapidly metabolized and renally eliminated. In numerous studies, pyrethroid metabolites have been detected in urine after occupational exposure to insecticides. In this study, we used a new, reliable, easy, and sensitive analytical method to assess the internal pyrethroid exposure of an urban population without exposure to pyrethoids at home or at work (children and adults). A total of 1,177 persons took part in this investigation, including 331 children under 6 years of age and 247 children between 6 and 12 years of age. None of them reported exposure to pyrethroids at home or at work. Accordingly, the levels of permethrin found in household dust from their homes were lower than expected (median < limit of detection; 95th percentile, 4.8 mg/kg; maximum value, 19 mg/kg). Urine specimens were analyzed for cis-3-(2,2-dibromo-vinyl)-2,2-dimethylcyclo-propanecarboxylic acid (Br(2)CA), cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-carboxylic acid (cis-Cl(2)CA and trans-Cl(2)CA), and 4-fluoro-3-phenoxybenzoic acid (F-PBA) using a gas chromatographic method with mass-selective detection. The limit of detection for pyrethroid metabolites was between 0.1 and 0.2 microg/L. trans-Cl(2)CA was detected in 65% of the urine specimens tested, cis-Cl(2)CA was detected in 30%, and Br(2)CA and F-PBA were found in 19% and 16%, respectively, of the urine specimens. The urinary metabolite levels in children did not differ from those in adults, and there was no correlation between the levels of metabolites and indoor exposure to permethrin in household dust. Moreover, no seasonal correlations could be found. The 95th percentile levels in urine specimens were as follows: Br(2)CA, 0.30 microg/L; cis-Cl(2)CA, 0.51 microg/L; trans-Cl(2)CA, 1.43 microg/L; F-PBA, 0.27 microg/L. Background exposure to pyrethroids was found in the general population; it seems to be caused by the uptake of pyrethroids with the diet. This hypothesis needs to be tested in duplicate diet studies combined with biomonitoring. As long as representative data are lacking, however, the rounded 95th percentile values obtained in our study may be used as reference values for pyrethroid metabolites in urine samples from the population in Germany; 95th percentile values for children and adults are as follows: Br(2)CA, 0.3 microg/L; cis-Cl(2)CA, 0.5 microg/L; trans-Cl(2)CA, 1.5 microg/L; and F-PBA, 0.3 microg/L.

Adolescent↗
PubMed2005

Developmental neurotoxicity of pyrethroid insecticides: critical review and future research needs.

Pyrethroid insecticides have been used for more than 40 years and account for 25% of the worldwide insecticide market. Although their acute neurotoxicity to adults has been well characterized, information regarding the potential developmental neurotoxicity of this class of compounds is limited. There is a large age dependence to the acute toxicity of pyrethroids in which neonatal rats are at least an order of magnitude more sensitive than adults to two pyrethroids. There is no information on age-dependent toxicity for most pyrethroids. In the present review we examine the scientific data related to potential for age-dependent and developmental neurotoxicity of pyrethroids. As a basis for understanding this neurotoxicity, we discuss the heterogeneity and ontogeny of voltage-sensitive sodium channels, a primary neuronal target of pyrethroids. We also summarize 22 studies of the developmental neurotoxicity of pyrethroids and review the strengths and limitations of these studies. These studies examined numerous end points, with changes in motor activity and muscarinic acetylcholine receptor density the most common. Many of the developmental neurotoxicity studies suffer from inadequate study design, problematic statistical analyses, use of formulated products, and/or inadequate controls. These factors confound interpretation of results. To better understand the potential for developmental exposure to pyrethroids to cause neurotoxicity, additional, well-designed and well-executed developmental neurotoxicity studies are needed. These studies should employ state-of-the-science methods to promote a greater understanding of the mode of action of pyrethroids in the developing nervous system.

Age Factors↗
PubMed2005

Risk of brain tumors in children and susceptibility to organophosphorus insecticides: the potential role of paraoxonase (PON1).

Prior research suggests that childhood brain tumors (CBTs) may be associated with exposure to pesticides. Organophosphorus insecticides (OPs) target the developing nervous system, and until recently, the most common residential insecticides were chlorpyrifos and diazinon, two OPs metabolized in the body through the cytochrome P450/paraoxonase 1 (PON1) pathway. To investigate whether two common PON1 polymorphisms, C-108T and Q192R, are associated with CBT occurrence, we conducted a population-based study of 66 cases and 236 controls using DNA from neonatal screening archive specimens in Washington State, linked to interview data. The risk of CBT was nonsignificantly increased in relation to the inefficient PON1 promoter allele [per PON1(-108T) allele, relative to PON1(-108CC): odds ratio (OR) = 1.4; 95% confidence interval (CI), 1.0-2.2; p-value for trend = 0.07]. Notably, this association was strongest and statistically significant among children whose mothers reported chemical treatment of the home for pests during pregnancy or childhood (per PON1(-108T) allele: among exposed, OR = 2.6; 95% CI, 1.2-5.5; among unexposed, OR = 0.9; 95% CI, 0.5-1.6) and for primitive neuroectodermal tumors (per PON1(-108T) allele: OR = 2.4; 95% CI, 1.1-5.4). The Q192R polymorphism, which alters the structure of PON1 and influences enzyme activity in a substrate-dependent manner, was not associated with CBT risk, nor was the PON1(C-108T/Q192R) haplotype. These results are consistent with an inverse association between PON1 levels and CBT occurrence, perhaps because of PON1's ability to detoxify OPs common in children's environments. Larger studies that measure plasma PON1 levels and incorporate more accurate estimates of pesticide exposure will be required to confirm these observations.

Aryldialkylphosphatase↗
PubMed1985

Structure-activity correlations for interactions of bicyclophosphorus esters and some polychlorocycloalkane and pyrethroid insecticides with the brain-specific t-butylbicyclophosphorothionate receptor.

[35S]t-Butylbicyclophosphorothionate or [35S]TBPS is an improved radioligand for the picrotoxinin binding site in rat brain synaptic membranes. The toxic isomers of the hexachlorocyclohexanes, polychlorobornanes, and chlorinated cyclodienes displace [35S]TBPS with a stereospecificity and potency generally correlated with their mammalian toxicity. In a few cases this correlation is improved by correction for metabolic activation or detoxification on using a coupled brain receptor/liver microsomal oxidase system. The alpha-cyano-3-phenoxybenzyl pyrethroids, although less potent, inhibit [35S]TBPS binding in a stereospecific manner correlated with their toxicity. Scatchard analyses indicate that these three classes of polychlorocycloalkane insecticides act at the TBPS binding site within the gamma-aminobutyric acid (GABA) receptor-ionophore complex whereas the alpha-cyano pyrethroids interact with a closely associated site. These insecticides and TBPS analogs may serve as useful probes further to elucidate the topography of the TBPS binding site and its relationship to the chloride channel.

Animals↗
PubMed1990

Mechanisms of toxic action and structure-activity relationships for organochlorine and synthetic pyrethroid insecticides.

The mechanisms and sites of action of organochlorine (DDT-types and chlorinated alicyclics) and synthetic pyrethroid insecticides are presented with discussion of symptoms, physiological effects, and selectivity. The structural requirements for toxicity are assessed, and structure-activity relationships are considered for each subclass. Lipophilicity is important for all the groups because it facilitates delivery of these neurotoxicants to the site of action in the nerve. Steric factors including molecular volume, shape, and isomeric configuration greatly influence toxicity. Electronic parameters also have been demonstrated to affect biological activity in some of the groups of insecticides, e.g., Hammett's sigma and Taft's sigma * as indicators of electronegativity. New synthetic pyrethroids continue to be developed, with varied structures and different physicochemical and biological properties.

Animals↗
PubMedDate not supplied

Methyl parathion: an organophosphate insecticide not quite forgotten.

Methyl parathion (MP), a toxic organophosphate insecticide approved for outdoor use only, is classified by the World Health Organization (WHO) as a Category Ia (extremely toxic) and by the United States Environmental Protection Agency (U.S. EPA) as a Toxicity Category I (most toxic) insecticide. In several U.S. states in the late 1980s and early 1990s, toxic exposures were created by the illegal use of MP indoors by uncertified pest control operators. As the health effects of MP exposure became evident with increasing public awareness, intervention by the U.S. government, in collaboration with several agencies and public initiatives, led to investigations of MP exposure. After evidence of MP metabolites from urine samples confirmed the exposure, in 1998 the indoor use of MP was banned in the U.S. to protect human health, especially that of children, and the environment. Toxic exposures to MP also occurred in developing countries. In El Salvador, occupational exposure to MP in farmers introduced environmental exposures among agricultural families, who presented with the cholinergic features of MP toxicity. Suicidal MP poisoning was reported in Nepal. A fatal accidental poisoning in children in Peru reflected the serious health risk of pesticides in developing countries. The negligence of pesticide exporters raised human rights issues over the tragedy. Nevertheless, MP exposure remains a potential health risk in both the U.S. and the developing world. Preventive measures in reducing the use of toxic chemicals should be taken seriously to protect human health and the environment.

Air Pollution↗
PubMedDate not supplied

Methylation of guanine in vivo by the organophosphorus insecticide methamidophos.

The methylating capability of methamidophos, assayed by the formation of [7-14C]methylguanine in mouse liver, was investigated using a 14C-insecticide labelled at the O--CH3 group. Following i.p. administration of the toxicant, [7-14C]methylguanine could be isolated from liver nucleic acids of treated mice. The amount of 14C-label reached its maximum 6 h following administration of the insecticide. At maximum 14C-labelling, the amount of 7-methylguanine calculated as fraction of applied dose, was 20-22 X 10(-4) and 98-104 X -4, for DNA and RNA, respectively. The results obtained indicate also, that an appreciable amount of 14C-activity is incorporate via the C-1 pool.

Animals↗
PubMedDate not supplied

Insect growth regulator and insecticidal activity of beta-dihydroagarofurans from Maytenus spp. (Celastraceae).

From the aerial parts of Maytenus disticha, we have isolated 9beta-benzoyloxy-1alpha,2alpha,6beta,8alpha,15penta-acetoxy-dihydro-beta-agarofuran (1) and from seeds of Maytenus boaria 9beta-furoyloxy-1alpha,6beta,8alpha-triacetoxy-dihydro-beta-agarofuran (2). These compounds and their MeOH and hexane/ethyl acetate (1:1 v/v) extracts were evaluated for their effects on the fall armyworm (Spodoptera frugiperda). Toosendanin, a commercial insecticide derived from Melia azedarach was used as a positive control. When tested for activity using neonate larvae in a nochoice artificial diet bioassays, the agarofurans 1, 2 and toosendanin as well as the MeOH and hexane/EtOAc extracts caused significant growth inhibitory effects with GC50 of 7.55; 3.84; 1.75; 14.0 and 7.3 ppm at 7 days, respectively. Compounds 1 and 2 caused 100% larval mortality at 25 and 15 ppm, respectively. MeOH and hexane/EtOAc extracts caused 100% larval mortality at 25.0 ppm, respectively, they also increased the development time of surviving larvae and a significant delay for the time of pupation and adult emergence. These compounds showed comparable potency of activity with toosendanin. Acute toxicity against adults of S. frugiperda was also found, for hexane/EtOAc extract and 2 had the most potent activity with LD50 value of 4.7 and 1.9 ppm, respectively. MeOH extract, hexane/EtOAc extract, 1 and 2 caused acetylcholinesterase inhibition with 78.0, 89.2, 79.3 and 100% inhibition at 15.0 ppm, respectively. Therefore, the furoyloxy agarofuran may be responsible for the insecticidal activity of these plants.

Animals↗
PubMedDate not supplied

Secondary metabolites and insecticidal activity of Anemone pavonina.

The insecticidal properties of the crude extracts of the leaves and flowers of Anemone pavonina were evaluated on Pheidole pallidula ants and showed significant levels of activity. Bioassay-guided fractionations led to the isolation of the butenolide ranunculin (1) as the active principle. Chemical investigations of the extracts showed them to contain as major components the sitosterol glycopyranoside lipids 2-5 and the glycerides 6-8. The structures of the metabolites were elucidated, following acetylation and hydrolysis of the natural products, by interpretation of their NMR and mass spectral data. The uncommon lipid metabolites 2-8 were isolated for the first time from the genus Anemone and this is the first report of insecticidal activity of the Anemone metabolite ranunculin against ants.

Anemone↗
PubMedDate not supplied

Lethality of triatomines (Hemiptera: Reduviidae), vectors of Chagas' disease, feeding on blood baits containing synthetic insecticides, under laboratory conditions.

A laboratory study was conducted to test the toxicity of synthetic insecticides added to defibrinated sheep blood kept at room temperature and offered as food to the following triatomine species: Triatoma infestans, Panstrongylus megistus, Triatoma vitticeps, Triatoma pseudomaculata, Triatoma brasiliensis and Rhodnius prolixus. The insecticides used, at a concentration of 1 g/l, were: HCH, DDT, Malathion and Trichlorfon, and the lethalithy observed at the end of a 7-day period varied according to the active principle of each. HCH was the most effective by the oral route, killing 100% of the insects, except P. megistus (95.7%) and T. pseudomaculata (94.1%). Trichlorfon killed the insects at rates ranging from 71.8% (T. vitticeps) to 98% (R. prolixus). Malathion was slightly less efficient, killing the insects at rates from 56.8% (T. vitticeps) to 97% (T. brasiliensis). DDT was the least effective, with a killing rate of 10% (T. vitticeps) to 75% (T. brasiliensis). Since the tests were performed at room temperature, we suggest that baits of this type should be tried for the control of triatomines in the field.

Animals↗