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 1,459 records · Page 81Linked to original sources
PubMed2004

Impacts of residual insecticide barriers on perimeter-invading ants, with particular reference to the odorous house ant, Tapinoma sessile.

Three liquid insecticide formulations were evaluated as barrier treatments against perimeter-invading ants at a multifamily housing complex in West Lafayette, IN. Several ant species were present at the study site, including (in order of abundance) pavement ant, Tetramorium caespitum (L.); honey ant, Prenolepis imparis (Say); odorous house ant, Tapinoma sessile (Say); thief ant, Solenopsis molesta (Say); acrobat ant, Crematogaster ashmeadi (Mayr); crazy ant, Paratrechina longicornis (Latrielle), field ants, Formica spp.; and carpenter ant Camponotus pennsylvanicus (DeGeer). Studies began in May 2001 and concluded 8 wk later in July. Individual replicate treatments were placed 0.61 in (2 feet) up and 0.92 m (3 feet) out from the ends of 46.1 by 10.1-m (151 by 33-foot) apartment buildings. Ant sampling was performed with 10 placements of moist cat food for 1 h within treatment zones, followed by capture and removal of recruited ants for later counting. All treatments led to substantial reductions in ant numbers relative to untreated controls. The most effective treatment was fipronil, where 2% of before-treatment ant numbers were present at 8 wk after treatment. Both imidacloprid and cyfluthrin barrier treatments had efficacy comparative with fipronil, but to 4 and 2 wk, respectively. Odorous house ants were not sampled before treatment. Comparisons of ant species composition between treatments and controls revealed an increase in odorous house ant frequencies at 1-8 wk after treatment in treated locations only. These results demonstrate efficacy for both nonrepellent and repellent liquid insecticides as perimeter treatments for pest ants. In addition, our findings with odorous house ant highlight an apparent invasive-like characteristic of this species that may contribute to its dramatic increase in structural infestation rates in many areas of the United States.

Animals↗
PubMed2005

Seasonal expression profiles of insecticidal protein and control efficacy against Helicoverpa armigera for Bt cotton in the Yangtze River valley of China.

Seasonal levels of Bacillus thuringiensis (Bt) insecticidal protein and its control efficacy against Helicoverpa armigera (Hübner) in Bt transgenic cotton GK19 (carrying a Cry1Ac/Cry1Ab fused gene) and BG1560 (carrying a Cry1Ac gene) were investigated in Tianmen County, Hubei Province, located in the Yangtze River valley of China, in 2001 and 2002. The results showed that the toxin content in Bt cotton changed significantly over time, and that the structure, growth stage, and variety were significant sources of variability. Generally, insecticidal protein levels were high during the early stages of cotton growth; they declined in mid-season, and rebounded in late season. On most dates sampled, the toxin contents in leaf, square, petal, and stamens (including nonovule pistil tissue) were much higher than those in ovule and boll. Compared with BG1560, the expression of Cry1Ac/Cry1Ab protein in GK19 was more variable during the whole growth period of cotton. The field evaluation on larval population dynamics of H. armigera in Bt and conventional cotton showed that the larval densities in BG1560 and GK19 fields decreased, respectively, 92.04 and 81.85% in 2001, and 96.84 and 91.80% in 2002.

Animals↗
PubMed1991

Studies on the control of plague in the western United States: laboratory trials of six insecticide dust formulations applied to soil for the control of the plague vector Oropsylla montana (Siphonaptera: Ceratophyllidae).

In this study, six insecticide dust formulations were laboratory-tested in soil mixtures ranging in concentration from 40 to 1,280 parts per million (ppm) against a proven vector of bubonic plague, Oropsylla montana (Baker). Pulicidal effects of the six insecticides, which included three organophosphates, two carbamates, and a pyrethroid, were compared by LD(50) values at both ambient and 75% RH. Permethrin (Pyraperm 455 dust), a pyrethroid with a LD(50) less than 40 ppm, demonstrated the most effective pulicidal action for the 13-wk trial period, followed in order by chlorpyrifos, bendiocarb, propetamphos, diazinon, and carbaryl.

Animals↗
PubMed2005

High resistance to pyrethroid insecticides associated with ineffective field treatments in Triatoma infestans (Hemiptera: Reduviidae) from Northern Argentina.

Field populations of Triatoma infestans Klug were collected during 2002 from four villages in northern Argentina (El Chorro, La Toma, El Sauzal, and Salvador Mazza), after application of deltamethrin and other pyrethroids was ineffective. High levels of resistance to the pyrethroid insecticides deltamethrin, beta-cypermethrin, beta-cyfluthrin, and lambda-cyhalothrin were detected in all of the evaluated populations. The resistance ratio to pyrethroids determined by topical application ranged from 50.5 (deltamethrin, El Sauzal) to 667.6 (beta-cyfluthrin, Salvador Mazza). None of the pyrethroid-resistant insects was resistant to the organophosphorus insecticide fenitrothion. Topical application of piperonyl butoxide to the most deltamethrin-resistant population (Salvador Mazza) led to slight reduction in levels of resistance. Activity of P450 monooxygenase, measured in individual insects through ethoxycoumarine-O-deethylase, showed a slight but noticeable difference in the distribution of activities between susceptible and resistant populations. The total percentage of insects below 0.48 pmol of 7-OH coumarine/min/ insect was 36.4 for Salvador Mazza population and 64.3 pmol of 7-OH coumarine/min/insect for CIPEIN strain. Whereas a low level of resistance to deltamethrin was previously related to monooxygenase activity in T. infestans, the high levels of resistance shown by these populations seem to involve monooxygenase in combination with other resistance mechanisms, for example, insensitivity of nervous membrane. Research on T. infestans resistance is in progress to improve Chagas vector control programs in Latin America and to implement resistance management strategies.

Animals↗
PubMed1990

In vivo genotoxic effects in mice of Metacid 50, an organophosphorus insecticide.

The genotoxic effect of methyl parathion, an organophosphorus insecticide commercially available as Metacid 50, was studied in Swiss albino mice using bone marrow and peripheral blood micronucleus tests. Single acute oral doses of the insecticide at concentrations of 75.0, 37.5, 18.75 and 9.375 mg/kg body weight, equivalent to 1/2 LD50, 1/4 LD50, 1/8 LD50 and 1/16 LD50, administered to female mice, elicited positive responses in bone marrow and peripheral blood micronuclei tests. Statistically significant increases in the frequency of micronuclei were observed at higher doses in both the tests performed. The data obtained for our experiments suggest that methyl parathion is a potent mutagen and so it is also likely to have a genotoxic effect in humans.

Animals↗
PubMed2002

Acetylcholinesterase engineering for detection of insecticide residues.

To detect traces of insecticides in the environment using biosensors, we engineered Drosophila acetylcholinesterase (AChE) to increase its sensitivity and its rate of phosphorylation or carbamoylation by organophosphates or carbamates. The mutants made by site-directed mutagenesis were expressed in baculovirus. Different strategies were used to obtain these mutants: (i) substitution of amino acids at positions found mutated in AChE from insects resistant to insecticide, (ii) mutations of amino acids at positions suggested by 3-D structural analysis of the active site, (iii) Ala-scan analysis of amino acids lining the active site gorge, (iv) mutagenesis at positions detected as important for sensitivity in the Ala-scan analysis and (v) combination of mutations which independently enhance sensitivity. The results highlighted the difficulty of predicting the effect of mutations; this may be due to the structure of the site, a deep gorge with the active serine at the bottom and to allosteric effects between the top and the bottom of the gorge. Nevertheless, the use of these different strategies allowed us to obtain sensitive enzymes. The greatest improvement was for the sensitivity to dichlorvos for which a mutant was 300-fold more sensitive than the Drosophila wild-type enzyme and 288 000-fold more sensitive than the electric eel enzyme, the enzyme commonly used to detect organophosphate and carbamate.

Acetylcholinesterase↗
PubMed2000

A small-volume bioassay for quantification of the esterase inhibiting potency of mixtures of organophosphate and carbamate insecticides in rainwater: development and optimization.

The goal of this study was to develop a sensitive in vitro bioassay for quantification of the total esterase inhibiting potency of low concentrations of organophosphate and carbamate insecticides in relatively small rainwater samples. Purified acetylcholinesterase (AChE) from electric eel (Electrophorus electricus) and carboxylesterases from a homogenate of honeybee heads (Apis mellifera) were used as esterases, each having different affinities for the substrates S-acetylthiocholine-iodide (ATC) and N-methylindoxylacetate (MIA). MIA hydrolysis by honeybee homogenate was more sensitive to inhibition by organophosphate insecticides than ATC hydrolysis by purified AChE, although the latter parameter is often used for in vitro monitoring of esterase inhibitors. The higher sensitivity of carboxylesterases is attributed to the instant formation of a reversible Michaelis-Menten complex with the inhibitor, which competes with MIA for the active sites of the free enzymes. This dose-dependent instant inhibition can be quantified with kinetics for competitive inhibition at dichlorvos concentrations < 16 nM. At similar concentrations, purified AChE was not instantly inhibited, whereas both AChE and carboxylesterases were irreversibly and progressively inhibited at higher dichlorvos concentrations (IC50(10min) >/= 0.1 microM). Honeybee homogenate mediated MIA hydrolysis was applied as the most sensitive enzyme-substrate combination for experiments with fractionated extracts of 4 rainwater samples collected in a natural conservation area. Most esterase inhibiting potency was found in the polar methanol fraction, with recalculated concentrations equivalent to 12-125 ng dichlorvos per liter rainwater.

Acetylcholinesterase↗
PubMed2004

Organophosphorus insecticides induce airway hyperreactivity by decreasing neuronal M2 muscarinic receptor function independent of acetylcholinesterase inhibition.

We previously demonstrated that the organophosphorus (OP) insecticide chlorpyrifos potentiates vagally induced bronchoconstriction independent of acetylcholinesterase (AChE) inhibition by decreasing the function of neuronal M2 muscarinic receptors that normally inhibit acetylcholine release from parasympathetic nerves supplying airway smooth muscle. However, it has been reported that different OPs may not affect muscarinic receptors equally. To determine if the effects of chlorpyrifos on airway hyperreactivity can be generalized to other OPs, we tested whether parathion and diazinon also inhibit neuronal M2 receptor function resulting in airway hyperreactivity. In control animals, the M2 agonist pilocarpine inhibits vagally induced bronchoconstriction in a dose-related manner. Treatment of guinea pigs with either parathion (1-10 mg/kg, sc) or diazinon (0.75-75 mg/kg, sc) shifted pilocarpine dose-response curves significantly to the right, indicating loss of neuronal M2 receptor function. These OP treatments also significantly potentiated vagally induced bronchoconstriction. Treatments that did not decrease M2 receptor function (parathion at 0.1 mg/kg, sc, or the non-OP insecticide permethrin at 150 mg/kg, sc) also did not cause airway hyperreactivity. None of the OP treatments altered bronchoconstriction induced by iv acetylcholine or methacholine in vagotomized guinea pigs, suggesting that OP-induced airway hyperreactivity is not due to altered function of muscarinic receptors on airway smooth muscle or to AChE inhibition. AChE assays of lung, blood, and brain confirmed that parathion and diazinon decreased M2 function at concentrations that did not inhibit AChE. These data suggest that multiple diethyl phosphorothionate OPs cause airway hyperreactivity via a common mechanism of M2 receptor dysfunction independent of AChE inhibition.

Acetylcholinesterase↗
PubMed2006

The common insecticides cyfluthrin and chlorpyrifos alter the expression of a subset of genes with diverse functions in primary human astrocytes.

Given the widespread use of insecticides in the environment, it is important to perform studies evaluating their potential effects on humans. Organophosphate insecticides, such as chlorpyrifos, are being phased out; however, the use of pyrethroids in household pest control is increasing. While chlorpyrifos is relatively well studied, much less is known about the potential neurotoxicity of cyfluthrin and other pyrethroids. To gain insights into the neurotoxicity of cyfluthrin, we compared and evaluated the toxicity profiles of chlorpyrifos and cyfluthrin in primary human fetal astrocytes. We found that at the same concentrations, cyfluthrin exerts as great as, or greater toxic effects on the growth, survival, and proper functioning of human astrocytes. By using microarray gene expression profiling, we systematically identified and compared the potential molecular targets of chlorpyrifos and cyfluthrin, at a genome-wide scale. We found that chlorpyrifos and cyfluthrin affect a similar number of transcripts. These targets include molecular chaperones, signal transducers, transcriptional regulators, transporters, and those involved in behavior and development. Further computational and biochemical analyses show that cyfluthrin and chlorpyrifos upregulate certain targets of the interferon-gamma and insulin-signaling pathways and that they increase the protein levels of activated extracellular signal-regulated kinase 1/2, a key component of insulin signaling; interleukin 6, a key inflammatory mediator; and glial fibrillary acidic protein, a marker of inflammatory astrocyte activation. These results suggest that inflammatory activation of astrocytes might be an important mechanism underlying neurotoxicity of both chlorpyrifos and cyfluthrin.

Apoptosis↗
PubMed2006

The effects of anticholinergic insecticides on human mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are located primarily in the bone marrow and are characterized by their capacity to differentiate into mesenchymal lineages such as bone, fat, and cartilage in response to appropriate signals. Several signaling mechanisms act to control MSC survival, proliferation, and differentiation, and failure or disruption of these signaling pathways can lead to degenerative disease or neoplasia. Organophosphate (OP) and carbamate pesticides, which are used in large amounts in agriculture to control insects, are designed to disrupt acetylcholine signaling by inhibiting the enzyme acetylcholinesterase (AChE). Effects of OP and carbamate pesticides on the human central nervous system have been well documented. However, AChE is broadly distributed, and the effects of anticholinergic insecticides on nonnervous tissue have received little attention. In the present study we found that human MSCs express AChE, which makes these cells potential targets for AChE inhibiting agents. We therefore examined the effects of an OP pesticide, chlorpyrifos, and a carbamate, carbofuran, on MSC characteristics. It was found that micromolar concentrations of these anticholinergic insecticides had no effect on MSC survival or proliferation but limited MSC differentiation capacity by inhibiting osteogenic differentiation. These results demonstrate that exposure to micromolar concentrations of OP and carbamate pesticides may affect tissue turnover and pathophysiology by interfering with MSC regulation.

Acetylcholinesterase↗
PubMed1979

Pancreatitis as a complication of anticholinesterase insecticide intoxication.

Severe pancreatitis and a pseudocyst occurred in a patient following accidental ingestion of an anticholinesterase insecticide, a substance not previously known to produce pancreatitis. Experiments were done to elucidate the mechanism. In one group of dogs the pancreatic duct was perfused and intraductal pressures were measured. The cholinesterase inhibitor 0,0-diethyl-0-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate (25 mg/kg) caused a significant increase in the mean intraductal pressure from 12 +/- 2.4 to 27.8 +/- 5.9 cm saline. In a second group of dogs pancreatic secretory rates were measured. Anticholinesterase (75 mg/kg) in combination with secretin infusion (1 U/kg/hr) caused a significant increase in the secretin stimulated flow rate from 0.13 to 0.56 cc/min. Atropine (75 microgram/kg) abolished the anticholinesterase induced pressure and secretory rate increases. In a third group of dogs administration of cholinesterase inhibitor 75 mg/kg and secretin infusion 2 U/kg/hr resulted in acute pancreatic interstitial edema, acinar cell vacuolization, hyperamylasemia and hyperlipasemia. These results suggest that occurrence of pancreatitis as a complication of anticholinesterase insecticide intoxication is the result of hypersecretion and pharmacologic ductal obstruction.

Adult↗
PubMed2001

Insecticidal activity of common reagents for insect foreign bodies of the ear.

OBJECTIVE: Insects commonly present as painful and distressing foreign bodies of the external ear canal. Removing live insects can be challenging, especially for primary care physicians who have limited equipment. The purpose of this study is to compare the insecticidal activity of commonly available preparations for insects that are most frequently recovered from ear canals: cockroaches (German and American), ticks, beetles, and honeybees. STUDY DESIGN: Prospective, blinded. METHODS: One hundred seventy insects of each species were placed in test tubes and submerged in 17 test preparations (10 tubes per preparation, 1 insect per test tube). Insect activity was stimulated by agitation of the test tube. Responses were monitored, and the time until death was measured. RESULTS: Most test preparations exhibited some insecticidal activity against most insect species. Ticks were completely resistant to all of the test reagents. Ethanol killed the American cockroaches (mean time, 32.6 s), German cockroaches (mean time, 29.6 s), and honeybees (mean time, 19.6 s) the most rapidly. CONCLUSION: Many commonly available reagents may be used to kill or immobilize insect foreign bodies of the ear.

Acetic Acid↗
PubMed1996

Prevalence of and potential risk factors for symptoms associated with insecticide use among animal groomers.

Pet groomers make numerous insecticide applications during the flea season, but few studies have examined their health complaints. The Pesticide Control Program of the New Jersey Department of Environmental Protection conducted a health and safety survey of this population. All licensed pet applicators in New Jersey were contacted, as were New Jersey veterinarians listed as pet-animal practitioners by the American Veterinary Medical Association. Approximately 36% of the respondents indicated that during the 1994 flea season, they had experience at least one of the 17 symptoms associated with insecticide application. Central nervous system symptoms (headache, dizziness, or confusion) and skin symptoms (skin rash or numbness/tingling) were reported most frequently. Logistic regression results suggest that applications per season, years as an applicator, certain hygiene variables, certain classes of products, and status of applicator (veterinary vs veterinary) are potentially important risk factors.

Adolescent↗
PubMed2006

Exposure to nonpersistent insecticides and male reproductive hormones.

BACKGROUND: Urinary metabolites of several nonpersistent insecticides have been measured in a high percentage of men in the general population, suggesting widespread environmental exposures to these compounds. The present study explored the association of urinary concentrations of 3,5,6-trichloro-2-pyridinol (TCPY), a metabolite of chlorpyrifos and chlorpyrifos-methyl, and 1-naphthol (1N), a metabolite of carbaryl and naphthalene, with serum reproductive hormone levels in adult men. METHODS: Subjects (n = 268) were the male partners in couples presenting to a Massachusetts infertility clinic in years 2000 through 2003. TCPY and 1N were measured in a spot urine sample from each subject and adjusted for dilution using specific gravity. Reproductive hormones (follicle-stimulating hormone, leuteinizing hormone, inhibin B, testosterone, and sex hormone-binding globulin) were measured in serum collected from subjects during the same clinic visit. RESULTS: Multiple linear regression models showed an inverse association between TCPY and testosterone concentration. An interquartile range (IQR) increase in TCPY was associated with a decline of 25 ng/dL (95% confidence interval = -40 to -10) in testosterone concentration. The association appeared to be dose-dependent when exposure was divided into quintiles. The highest TCPY quintile was associated with a testosterone decline of 83 ng/dL (-128 to -39) compared with the lowest TCPY quintile. We also found inverse associations between TCPY and free androgen index and between 1N and testosterone, and suggestive inverse associations between TCPY and leuteinizing hormone and between 1N and free androgen index. CONCLUSION: In adult men, TCPY and 1N were associated with reduced testosterone levels. On a population level, these reductions are of potential public health importance because of widespread exposure to these nonpersistent insecticides.

Adult↗
PubMed1998

Cytochrome P450 monooxygenases and insecticide resistance in insects.

Cytochrome P450 monooxygenases are involved in many cases of resistance of insects to insecticides. Resistance has long been associated with an increase in monooxygenase activities and with an increase in cytochrome P450 content. However, this increase does not always account for all of the resistance. In Drosophila melanogaster, we have shown that the overproduction of cytochrome P450 can be lost by the fly without a corresponding complete loss of resistance. These results prompted the sequencing of a cytochrome P450 candidate for resistance in resistant and susceptible flies. Several mutations leading to amino-acid substitutions have been detected in the P450 gene CYP6A2 of a resistant strain. The location of these mutations in a model of the 3D structure of the CYP6A2 protein suggested that some of them may be important for enzyme activity of this molecule. This has been verified by heterologous expression of wild-type and mutated cDNA in Escherichia coli. When other resistance mechanisms are considered, relatively few genetic mutations are involved in insecticide resistance, and this has led to an optimistic view of the management of resistance. Our observations compel us to survey in more detail the genetic diversity of cytochrome P450 genes and alleles involved in resistance.

Amino Acid Substitution↗
PubMed1997

Insecticidal activity of a recombinant baculovirus containing an antisense c-myc fragment.

Attempts to develop baculovirus-based insecticides by insertion of genes encoding enzyme inhibitors, neuropeptides or toxins have met with some success. However, it is often difficult to ensure correct processing or secretion of the encoded peptides. Here we tested a simpler strategy by insertion of an antisense fragment of a host gene to block translation of a protein essential for larval growth and development. We selected the c-myc gene for two main reasons: (i) its protein is known to be well conserved in evolution and to have multiple essential functions during development; and (ii) c-myc family genes have yet to be characterized in insects, thus blockage of essential genes by anti-sense transcripts from a strong virus promoter could provide a sensitive test for the existence of myc-like gene products. An appropriate fragment of the human c-myc gene was inserted downstream from the polyhedrin promoter of Autographa californica nucleopolyhedrovirus and tested in bioassays on Spodoptera frugiperda larvae. Western blot analysis with a human c-myc antibody revealed an endogenous protein band which bound specifically to these antibodies. This band disappeared more rapidly from cells infected with the antisense c-myc recombinant virus than from those infected with c-myc-negative virus. Results of bioassays showed that the antisense construct stopped feeding as soon as the polyhedrin promoter-driven transcripts accumulated, followed shortly by death of the larvae. These results suggest that c-myc-like protein(s) exist in insects and that the antisense strategy is an effective approach to virus insecticide productions.

Animals↗
PubMed2006

Health effects of long-term exposure to insecticide-treated mosquito nets in the control of malaria in endemic regions, revised.

The endemicity of malaria in tropical areas of the world persists, especially in countries south of Saharan Africa. The efforts and concerns invested by the World Health Organization and other health agencies to eradicate malaria are commendable. However, in spite of all these efforts, the loss in economic and human resources continues. In a previous report, the long-term health effects of insecticide-impregnated bednet (IIBN) use were highlighted with the expectation of attracting serious thoughts and further research on the issue. This present paper is an update on that expectation. Results from a comprehensive literature search show that not much work has been done on the effects of long-term exposure to IIBNs in combating malarial infection. The efficacy of IIBNs is not in question. What is in question is whether long-term exposure to IIBNs have any health effects. The aims and outcomes of the research found in the literature on the subject to date seem to support only the efficacy of the temporal use of plain bednets, but not the use of IIBNs, and do not tell much about the long-term effects of IIBN exposure. All pesticides are toxic by nature and present risks of adverse effects. While there is agreement that IIBNs can be effective in reducing malarial morbidity and mortality under field trials, a number of factors relating to their long-term-exposure health effects have yet to be determined. Further reliable research projects are recommended urgently. However, some of the anticipated behavioral effects caused by insecticidal use will be avoided by the use of untreated nets instead.

Animals↗
PubMed2006

A dietary risk assessment of the pyrethroid insecticide resmethrin associated with its use for West Nile Virus mosquito vector control in California.

An outbreak of human illnesses associated with West Nile Virus (WNV) occurred in New York City in 1999. Since then, it has gradually spread westwards, reaching northern California for the first time in 2005. WNV is transmitted by several mosquito species and birds serve as the main reservoir. Several control measures have been used, targeting both the aquatic larvae and the adult mosquitoes. In the latter case, roosting birds in trees are sprayed with pyrethroid insecticides because these are highly toxic to mosquitoes, but have low avian toxicity. A request was made to use a resmethrin-containing insecticide during the month of October 2005 in California. Because resmethrin was not registered for use on growing crops, concerns were raised about potential crop contamination. Therefore, an expedited dietary risk assessment was conducted on resmethrin. Developmental toxicity in the rat (NOELs of 25 or 40 mg/kg/day) was used as the acute endpoint and dietary exposure was assessed using the DEEM-FCID computer program. Only crops growing above ground during October were considered. Margins of Safety (MOS) were found to be above 100, the level generally considered to be sufficient to protect public health when using an animal NOEL.

Animals↗