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At least 487 records · Page 27Linked to original sources
PubMed1993

Tissue distribution of microsomal cytochrome P-450 monooxygenases and their inducibility by phenobarbital in the insecticide resistant LPR strain of house fly, Musca domestica L.

Cytochrome P-450s, cytochrome b5, P-450 reductase, and four P-450 monooxygenase activities were abundant in proximal intestine (PI), Malpighian tubules (MT), and fat bodies (FB) in the insecticide resistant (LPR) strain of house fly. Insecticide resistance in LPR flies was associated with increases in P-450 monooxygenase activities in nearly all of these tissues relative to an insecticide susceptible strain. Cytochrome P-450lpr was present in all tissues and at higher levels in LPR than in susceptible flies suggesting that the role of P-450lpr in monooxygenase-mediated insecticide resistance is not due to its higher levels in a single tissue. However, it appears that fat bodies may have a major role in resistance due to their relatively large size and the abundance of P-450lpr in this tissue. Total cytochrome P-450s, cytochrome P-450lpr and P-450 monooxygenase activities were generally refractory to phenobarbital (PB) induction in LPR. This contrasts with a previous report in susceptible house flies showing that P-450 monooxygenases were induced by PB. It appears that total P-450s, cytochrome P-450lpr and monooxygenase activities were expressed at constitutive high levels in several tissues of LPR house flies.

Animals↗
PubMed2005

Relationship between toxicity of selected insecticides and expression of stress proteins (HSP, GRP) in cultured human cells: effects of commercial formulations versus pure active molecules.

Three carbamate (formetanate, methomyl, pyrimicarb) and one pyrethroid (bifenthrin) insecticides were investigated both as pure chemicals and as commercial formulations in order to unveil possible toxic effects of additives and solvents present in the commercial formulations and to evaluate the cellular stress response as a defense mechanism. Toxic effects were evaluated on A549 cells, derived from a human lung carcinoma, by measuring (1) threshold concentrations leading to a decrease of the growth rate (LOEC), (2) sublethal concentrations (SC) which arrested growth without killing the cells, and (3) expression levels of several stress proteins, i.e., HSP27, HSP72/73, HSP90, GRP78, and GRP94. As compared to the pure active molecule, LOEC appeared at lower concentrations when using the commercial formulations, i.e., Dicarzol (formetanate), Lannate20 (methomyl) and Talstar or Kiros EV (bifenthrin). Propylene glycol and propylene glycol monomethyl ether, respectively, present in Talstar and kiros, do not account for the high toxicity of these commercial formulations and do not potentiate the toxicity of bifenthrin. Additive but not synergistic adverse effects were observed when cells are exposed to a mixture of 4 different commercial formulations. Our results show that the concentrations of active molecules recommended in flori-cultural general use or for spray preparations are much higher than SC concentrations, as determined on A549 pulmonary cells. GRP78 was up-regulated by all the insecticides, commercial preparations being more efficient to trigger the stress reaction. This suggests that insecticides and additives present in commercial formulations disrupt ER functions. Conversely, HSP72/73 was found to be down-regulated by all the insecticides. This seems to be related with a decrease of protein synthesis in the cytosol, as a result of the ER unfolded protein response. Indeed, tunicamycin, known to inhibit N-linked glycosylation in the ER, was found to induce a similar inverse correlation between GRP78 overexpression and HSP72/73 under-expression. Expression of GRP94 was found to be increased and HSP27 lowered by the highest concentrations of bifenthrin commercial formulations. Methomyl and Lannate20 only induced an under-expression of HSP90.

Cell Line, Tumor↗
PubMed2005

A comparative study on the dissipation and microbial metabolism of organophosphate and carbamate insecticides in orchaqualf and fluvaquent soils of West Bengal.

An experiment has been conducted under laboratory conditions to investigate the effect of phorate (an organophosphate insecticide) and carbofuran (a carbamate insecticide) at their recommended field rates (1.5 and 1.0 kga.i.ha-1, respectively) on the growth and multiplication of microorganisms as well as rate of dissipation and persistence of the insecticidal residues including their metabolites in laterite (typic orchaqualf) and alluvial (typic fluvaquent) soils of West Bengal. Application of phorate and carbofuran in general, induced growth and development of bacteria, actinomycetes, fungi, N2-fixing bacteria and phosphate solubilizing microorganisms in both the soils and the stimulation was more pronounced with phorate as compared to carbofuran. Application of phorate recorded highest stimulation of fungi in laterite and actinomycetes in alluvial soil. Carbofuran on the other hand, augmented fungi and N2-fixing bacteria in laterite and actinomycetes in alluvial soil. Bacterial population was inhibited due to the application of carbofuran in alluvial soil. Phorate sulfoxide and phorate sulfone, the two metabolites of phorate and 3-hydroxycarbofuran and 3-ketocarbofuran, the two metabolites of carbofuran isolated were less persistent in both the soils. Phorate persisted in laterite and alluvial soils up to 45 and 60 days, respectively depicting the half-life (T1/2) 9.7 and 11.5 days, respectively while the T1/2 of carbofuran for the said soils were 16.9 and 8.8 days, respectively. No metabolite of carbofuran was detected in soils after 30 days of incubation while phorate sulfone persisted in alluvial soil even after 60 days of application of the insecticide.

Bacteria↗
PubMed2005

Assessment of insecticide contamination in runoff and stream water of small agricultural streams in the main soybean area of Argentina.

The first- and second-order streams, Brown and Horqueta, respectively, which are located in the main area of soybean production in Argentina were examined for insecticide contamination caused by runoff from nearby soybean fields. The insecticides most widely used in Argentina (chlorpyrifos, cypermethrin and endosulfan) were detected in sediments, suspended particles and water. Highest concentrations in suspended particles were 318 microg/kg for endosulfan in the stream Horqueta, while 226 microg/kg chlorpyrifos and 13.2 microg/kg cypermethrin were measured in the stream Brown. In the Horqueta stream 150 and 53 microg/kg chlorpyrifos and cypermethrin were detected in runoff sediments, respectively. Whereas cypermethrin concentrations in the suspended particles were relatively low, levels in the floodwater of Brown reached 0.7 microg/l. The highest chlorpyrifos concentration in floodwater was 0.45 microg/l in Brown. However, endosulfan was not detected in the water phase. In runoff water the highest concentrations measured were 0.3 microg/l for chlorpyrifos in Horqueta and 0.49 microg/l for cypermethrin in the Brown stream. On five sampling dates during the pesticide application period in Brown stream (2002/2003) the concentration of chlorpyrifos and cypermethrin in runoff and/or floodwater exceeded the water quality criteria for freshwater mentioned in this study. In three cases this insecticide concentration was measured in stream water, indicating an acute risk to aquatic life. The acute toxicity-exposure-ratio (TER) for chlorpyrifos and cypermethrin also shows an acute risk for aquatic invertebrates in the Brown stream. In the Horqueta chlorpyrifos concentrations in the runoff exceeded the safety levels three times during the application period (2001/2002), potentially endangering the aquatic fauna. Effects on aquatic macroinvertebrates after insecticide contamination were reported in earlier studies in Horqueta stream.

Agriculture↗
PubMed2004

Irrigation runoff insecticide pollution of rivers in the Imperial Valley, California (USA).

The Alamo and New Rivers located in the Imperial Valley, California receive large volumes of irrigation runoff and discharge into the ecologically sensitive Salton Sea. Between 1993 and 2002 we conducted a series of studies to assess water quality using three aquatic species: a cladoceran (Ceriodaphnia dubia), a mysid (Neomysis mercedis), and a larval fish (Pimephales promelas). Although no mortality was observed with the P. promelas, high-level toxicity to the invertebrate species was documented in samples from both rivers during many months of each year. Toxicity identifications and chemical analyses identified the organophosphorus insecticides (OP), chlorpyrifos and diazinon, as the cause of C. dubia toxicity. The extent of the C. dubia mortality was highly correlated with quantities of these OPs applied in the river watersheds. C. dubia mortality occurred during more months of our 2001/2002 study than in the 1990s investigations. During 2001/2002, the extensive C. dubia mortality observed in New River samples was caused by OP insecticide pollution that originated from Mexico. Mortality to N. mercedis in New River samples was likely caused by contaminants other than OP insecticides. Our studies document OP insecticide-caused pollution of the Alamo River over a 10-year period and provide the necessary information for remediation efforts.

Agriculture↗
PubMed2006

Differential sensitivity of rat voltage-sensitive sodium channel isoforms to pyrazoline-type insecticides.

Pyrazoline-type insecticides are potent inhibitors of insect and mammalian voltage-sensitive sodium channels. In mammals, there are nine sodium channel alpha subunit isoforms that have unique distributions and pharmacological properties, but no published data exist that compare the relative sensitivity of these different mammalian sodium channel isoforms to inhibition by pyrazoline-type insecticides. This study employed the Xenopus oocyte expression system to examine the relative sensitivity of rat Na(v)1.2a, Na(v)1.4, Na(v)1.5, and Na(v)1.8 sodium channel alpha subunit isoforms to the pyrazoline-type insecticides indoxacarb, DCJW, and RH 3421. Additionally, we assessed the effect of coexpression with the rat beta1 auxiliary subunit on the sensitivity of the Na(v)1.2a and Na(v)1.4 isoforms to these compounds. The relative sensitivity of the four sodium channel alpha subunits differed for each of the three compounds we examined. With DCJW, the order of sensitivity was Na(v)1.4 > Na(v)1.2a > Na(v)1.5 > Na(v)1.8. In contrast, the relative sensitivity of these isoforms to indoxacarb differed from that to DCJW: the Na(v)1.8 isoform was most sensitive, the Na(v)1.4 isoform was completely insensitive, and the sensitivities of the Na(v)1.5 and Na(v)1.2a isoforms were intermediate between these two extremes. Moreover, the pattern of sensitivity to RH 3421 among these four isoforms was different from that for either indoxacarb or DCJW: the Na(v)1.4 isoform was most sensitive to RH 3421, whereas the sensitivities of the remaining three isoforms were substantially less than that of the Na(v)1.4 isoform and were approximately equivalent. The only statistically significant effect of coexpression of either the Na(v)1.2a or Na(v)1.4 isoforms with the beta1 subunit was the modest reduction in the sensitivity of the Na(v)1.2a isoform to RH 3421. These results demonstrate that mammalian sodium channel isoforms differ in their sensitivities to pyrazoline-type insecticides.

Animals↗
PubMed2006

Impact of the botanical insecticide Neem Azal on survival and reproduction of the biting louse Damalinia limbata on angora goats.

Secondary metabolites present in the neem tree (Azadirachta indica A. Juss, Meliaceae), exhibit a wide range of biological activities in insects. However, few studies have been undertaken to assess the potential of neem products as insecticides for the control of ectoparasites of domestic animals. This study was undertaken to estimate the efficacy of Neem Azal, an azadirachtin-rich extract of neem seeds, in controlling Damalinia limbata (Phthiraptera) louse infestation of angora goats. The study was conducted on a fibre animal farm situated in Central Italy. Groups of 11-12 goats were treated with Neem Azal at an azadirachtin concentration of 650ppm or 125ppm, with Neguvon or were left untreated. Their louse burden was assessed fortnightly to monthly for 22 weeks. A reduction in louse densities of 76-96% was observed from week 2 to week 18 after treatment with the neem solution containing azadirachtin at a concentration of 650ppm. At the lower test concentration (125ppm) a reduction of 60-92% could be recorded from week 2 to week 14. Neem Azal was found to reduce the survival of both adult and nymph stages of D. limbata and to interfere with oviposition and oogenesis of female lice. A decrease in oviposition was observed in neem exposed female lice and the examination of their ovaries revealed morphological alterations in both vitellogenic and previtellogenic ovarioles at the follicular and germinal level. Since neem compounds target different life stages and physiological processes of D. limbata, the development of insecticide resistance by biting lice exposed to neem-based insecticides appears unlikely. For this reason and for its prolonged activity, which in principle allows angora goats to be protected for a large part of the mohair production cycle, neem-based insecticides may have a potential interest for mohair producing breeders.

Animals↗
PubMed1977

Detection and determination of organophosphorus insecticides in tissues by thin-layer chromatography.

The toxicological analysis of 12 common organophosphorus insecticides is described. Suitable methods for the extraction of organophosphorus insecticides from tissues are proposed. The detection, identification and estimation of these insecticides by thin-layer chromatography is described for 25 solvent systems and a series of chromogenic reagents. The distribution of insecticides in human body tissues in five cases of poisoning by ethyl parathion, malathion, dimethoate, sumithion and phosphamidon has also been studied.

Autopsy↗
PubMed2000

Effect of organochlorine insecticides on nicotinic acetylcholine receptor-rich membranes.

The so-called generalized polarization (GP) of the fluorescent probe Laurdan and the steady-state fluorescence anisotropy of the probe diphenylhexatriene (DPH) and its phenylpropionic derivative (PA-DPH) were used to study the effects of several organochlorine insecticides of the chlorophenylethane, chlorinated cyclohexane and chlorinated cyclodiene families on the Torpedo nicotinic acetylcholine receptor (AChR)-rich native membrane. All insecticides, with the exception of Lindane, augmented Laurdan GP both in the native membrane and in model lipid systems. Most organochlorine compounds produced a concentration-dependent decrease of DPH and PA-DPH anisotropy in the AChR-rich membrane. These compounds exhibited a dual behavior vis-à-vis the native AChR-rich membrane, exerting disordering effects at the bilayer core while ordering and/or excluding water molecules from the lipid-protein interface region, as sensed by DPH anisotropy and Laurdan GP, respectively. Furthermore, all insecticides decreased the efficiency of fluorescence resonance energy transfer between the intrinsic protein and Laurdan, albeit to different extents. On the basis of all these observations, the existence of potential target sites for insecticides in the protein-lipid interface region is postulated.

2-Naphthylamine↗
PubMed2000

Insecticidal rocaglamide derivatives from Aglaia spectabilis (Meliaceae).

Bark of Aglaia spectabilis collected on the island of Phu Quoc (Vietnam) yielded insecticidal cyclopentatetrahydrobenzofurans of the rocaglamide type including four new natural products. Structure elucidation of the new compounds is described. All rocaglamide derivatives isolated exhibited strong insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis when incorporated into an artificial diet. LC50 values varied from 0.8 to 80 ppm. The most active compounds isolated, methylrocaglate and C-3' hydroxylmethylrocaglate, were similar with regard to their insecticidal activity to the well-known natural insecticide azadirachtin.

Benzofurans↗
PubMedDate not supplied

Insecticide-treated materials, mosquito adaptation and mass effect: entomological observations after five years of vector control in Burkina Faso.

Insecticide-treated bednets and curtains have been shown to be successful in reducing malaria transmission and child mortality in Africa over periods of up to 2 years. A major concern relating to this approach is that, in time, it will be compromised by the selection of mosquito genotypes that are resistant at the biochemical or behavioural level. We report entomological data from a large area in Burkina Faso where insecticide-treated curtains have been in use for up to 5 years. Longitudinal indoor and outdoor CDC light-trap catches were performed in 4 sentinel villages. In addition cross-sectional surveys using indoor spray catches and outdoor CDC light-trap catches were performed each September in a larger number of villages, including 8 located outside the intervention area. We found no evidence of the selection of mosquito phenotypes that might compromise the intervention. Indoor and outdoor vector densities remained very low after 5 years of intervention, both compared with pre-intervention levels and with concurrent levels outside the intervention area. We found no evidence of a switch to outdoor rather than indoor biting. The proportion of blood meals taken on humans may have decreased but our data are inconclusive on this point. We observed higher vector densities and sporozoite rates at the periphery of the intervention zone than at the centre, which may reflect re-invasion of peripheral villages by mosquitoes from outside the intervention area. In 'real life' programmes, with perhaps patchy, less than optimal coverage, the protection against malaria transmission provided to individuals using insecticide-treated materials may be less than that achieved in the randomized controlled trials which demonstrated an impact of insecticide-treated materials on child mortality.

Animals↗
PubMed2001

A comparison of the effects of organophosphate insecticide exposure and temperature stress on fluctuating asymmetry and life history traits in Culex quinquefasciatus.

Effects of exposure to a non-chemical (temperature) or chemical (organophosphate insecticide) stressor during larval development were compared in Culex quinquefasciatus mosquitoes. Stress was measured in two ways: using conventional life history traits (survival, development time and a measure of body size) and by calculating the degree of developmental instability from the departure from bilateral symmetry of wing characters (fluctuating asymmetry). Increasing insecticide dose, but not temperature, was observed to elevate wing fluctuating asymmetry in male but not female mosquitoes. Insecticide treatment reduced survival and was associated with a significant reduction in wing trait sizes in both females and males but did not significantly affect development time. Temperature was associated with a significant reduction in all life history traits in both sexes. Therefore wing fluctuating asymmetry in C. quinquefasciatus cannot be used as a general biomonitor of all stress, although it may have potential as a more specific monitor of chemical stress. It needs to be complimented with other measures such as life history and biochemical methods. The significant differences in response between sexes may impact on results of short-term larval exposures to insecticides.

Animals↗
PubMed1987

Insecticide use and increased mortality in rural Central Luzon, Philippines.

In a major rice-growing area of the Philippines, widespread adoption of insecticides by farmers on smallholdings was followed by a 27% increase in mortality from causes other than trauma among economically active men. Several factors suggest a causal link: highly toxic chemicals have been used unsafely; mortality has increased only in the age and sex class occupationally exposed; mortality has decreased among unexposed urban men; specific mortality rates have increased for those conditions likely to be confused with insecticide poisoning and have decreased for others; and, both within and between years, the pattern of mortality among men has reflected that of insecticide use. The results suggest that the currently accepted figure of 10,000 deaths annually worldwide due to accidental intoxication with insecticides is a substantial underestimate.

Adolescent↗
PubMed1998

Flavonoid-induced alterations in cytochrome P450-dependent biotransformation of the organophosphorus insecticide parathion in the mouse.

The majority of insecticides currently in use throughout the world belong to the class of the organophosphorus insecticides. Many of these compounds, such as the phosphorothioate insecticides, exert their mammalian toxicity only after undergoing metabolic activation by a variety of cytochrome P450 isoforms to produce their corresponding oxygen analogs (or oxons), which are potent inhibitors of the critical enzyme acetylcholinesterase. Of the many chemicals identified that can modulate cytochrome P450-dependent activities, the flavonoids represent some of the most unusual compounds in that they have been reported to both inhibit and stimulate certain activities. The present study was undertaken to determine if representative flavonoids (at in vitro concentrations of 1-100 microM) can alter the mammalian cytochrome P450-dependent biotransformation and acute toxicity of the phosphorothioate insecticide parathion. The flavonoids 5,6-benzoflavone, flavone, and quercetin had the biphasic effect of stimulating mouse hepatic microsomal parathion oxidation at a concentration of 1 microM, and inhibiting this same activity when increased to 100 microM. In contrast, 7,8-benzoflavone was only inhibitory at all concentrations examined. All the flavonoids examined except quercetin altered the ratio of activation/detoxification of parathion by mouse hepatic microsomes, but had no effect on this same ratio with human CYP1A2. These data suggest that the changes in the activation/detoxification ratio observed with mouse hepatic microsomes resulted from selective inhibition or stimulation of various cytochrome P450 isoforms rather than a flavonoid-induced alteration in the nonenzymatic rearrangement of the putative phosphooxythirane intermediate generated by cytochromes P450 from parathion. Surprisingly, however, none of the four flavonoids in the current study affected the lethality of parathion in vivo, suggesting that the flavonoid-induced alterations in cytochrome P-450-dependent metabolism of parathion documented in vitro were simply not great enough to be of any significance in vivo.

Animals↗
PubMed1999

The in vitro response of sheep scab mites to pyrethroid insecticides.

The response of sheep scab mites to pyrethroid insecticides and organophosphate compounds was studied in vitro with the objective of finding a simple test for detecting insecticide resistance in scab mites. Psoroptes cuniculi from rabbits or P. ovis from sheep were enclosed in small 'tea bags' made from heat sealable paper prior to dipping in insecticide. Mites failed to die 24 h after a 1 min dip in working concentrations of insecticidal sheep dips. With flumethrin a variety of different conditions were tested but most failed to improve the efficacy of flumethrin. It is suggested with freshly collected mites pyrethroids may be taken up by ingestion.

Animals↗
PubMed2001

GABA receptor subunit composition relative to insecticide potency and selectivity.

Three observations on the 4-[(3)H]propyl-4'-ethynylbicycloorthobenzoate ([(3)H]EBOB) binding site in the gamma-aminobutyric acid (GABA) receptor indicate the specific target for insecticide action in human brain and a possible mechanism for selectivity. First, from published data, alpha-endosulfan, lindane and fipronil compete for the [(3)H]EBOB binding site with affinities of 0.3--7 nM in both human recombinant homooligomeric beta 3 receptors and housefly head membranes. Second, from structure-activity studies, including new data, GABAergic insecticide binding potency on the pentameric receptor formed from the beta 3 subunit correlates well with that on the housefly receptor (r=0.88, n=20). This conserved inhibitor specificity is consistent with known sequence homologies in the housefly GABA receptor and the human GABA(A) receptor beta 3 subunit. Third, as mostly new findings, various combinations of alpha 1, alpha 6, and gamma 2 subunits coexpressed with a beta 1 or beta 3 subunit confer differential insecticide binding sensitivity, particularly to fipronil, indicating that subunit composition is a major factor in insecticide selectivity.

Animals↗
PubMed2002

Enzymes involved in the detoxification of organophosphorus, carbamate and pyrethroid insecticides through hydrolysis.

The most employed insecticides for indoor and agriculture purposes belong to carbamates, pyrethroid or organophosphates. The chemical structures of these three groups correspond to carbamic, carboxylic and triphosphoric esters. Technical monographs suggest that the hydrolysis of ester bonds of carbamates and pyrethroids plays an important role in the detoxification of these compounds. However, detailed studies about enzymes hydrolysing carbamates and pyrethroids in vertebrates are not available. Certain carbamate hydrolysing activities are associated to serum albumin. Phosphotriesterases, being of an unknown physiological role, hydrolyse (in some cases stereospecifically) organophosphorus insecticides (OP). Phosphotriesterases have been found in a multitude of species, from mammals to bacteria. A phosphotriesterase activity, EDTA-resistant, has been detected in serum albumin. Phosphotriesterases in serum of mammals display polymorphisms. Phosphotriesterases offer applications in therapy of organophosphorus poisonings, in biodegradation and bioremedation of organophosphates. Similar studies should be developed with enzymes hydrolysing pyrethroids and carbamate insecticides. Such studies will improve the knowledge of the detoxification routes in non-target species and will help to design specific and safer carbamate and pyrethroid insecticides.

Animals↗
PubMed2003

Long-term ecological assessment of West African rivers treated with insecticides: methodological considerations on quantitative analyses.

For the control of the aquatic stage of the blackfly vector of the onchocerciasis in West Africa, rivers had been partially sprayed weekly with insecticides from 1974 to 2002 on an area over 1 million km(2), as part of the onchocerciasis control programme (OCP). To evaluate the possible short- and long-term effects of insecticides on non-target fauna, an aquatic monitoring programme was set-up and carried on for over 20 years. A number of papers have been published concluding that biological variations found are ecologically acceptable. In this paper, by means of a new elaboration of a subset of data, the authors discuss value and limitations of the data analysis methodologies utilised in the ecological assessment. Multivariate analysis, rank-abundance curves and diversity indices are applied to evaluate the modification occurred in invertebrate community taxa richness and evenness. These methodologies allow to decompose the variance between insecticides effects and seasonal biological variations, to evidence the relative toxicological potency and to show the fingerprint of action among various insecticides.

Africa, Western↗