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PubMed2006

Variation of Musca domestica L. acetylcholinesterase in Danish housefly populations.

Anti-cholinesterase resistance is in many cases caused by modified acetylcholinesterase (MACE). A comparison was made of toxicological data and AChE activity gathered from 21 field populations and nine laboratory strains of houseflies, Musca domestica L., to elucidate the best way of generating data to provide advice for management strategies and gathering information for resistance risk assessment on the organophosphates azamethiphos and dimethoate and the carbamate methomyl, which have been the primary insecticides used against adult houseflies in Denmark. Cluster analysis was performed and > 2000 houseflies were assigned to one of three phenotypes based on total acetylcholinesterase activity as well as inhibition by azamethiphos, methomyl or omethoate. A cluster, i.e. a phenotype, with high total AChE activity and high sensitivity to azamethiphos and less sensitivity to inhibition by methomyl and omethoate was shown to be linked to methomyl resistance. It was not possible to define any clusters that could be linked to azamethiphos or dimethoate resistance. The five mutations V180L, G262A, G262V, F327Y and G365A causing anticholinesterase resistance in houseflies were all identified in the Danish housefly strains. The data are very heterogeneous, and a correlation of molecular genetic background and resistance of phenotypes is not obvious with the available data.

Acetylcholinesterase↗
PubMed2001

Leaf surfaces and the bioavailability of pesticide residues.

Laboratory bioassays were carried out to determine the toxicity to Folsomia candida Willem (Collembola: Isotomidae) of residues of a pyrethroid insecticide, deltamethrin, and an organophosphorus insecticide, dimethoate, on different leaf surfaces. The test leaves included a range of species and leaves of different ages. Dose-response relationships were estimated for F candida walking over the various treated leaf substrates. Probit analysis was used to estimate the means and standard deviations of the associated tolerance distributions expressed as gAIha-1. Parallelism tests were undertaken to compare the susceptibilities of F candida to the two compounds applied to the different leaf surfaces. On deltamethrin-treated leaf surfaces, the LD50 values for F candida varied from 6.36 to 77.14 gAIha-1. F candida was least susceptible to deltamethrin residues when applied to leaves of dwarf bean (Phaseolus vulgarus L) and the highest susceptibility was observed following application to leaves of seedlings of barley (Hordeum vulgare L). In contrast, the LD50 values observed for dimethoate treatments did not differ significantly between leaf types, ranging from 1.35 to 8.69 gAIha-1. The laboratory data on susceptibility of F candida on different leaf types for different pesticides can be used to investigate the role of leaf surface properties in modifying the toxicity of applied pesticides to exposed invertebrates.

Animals↗
PubMed2002

Susceptibility of house flies (Diptera: Muscidae) exposed to commercial insecticides on painted and unpainted plywood panels.

House flies were collected from dairies in New York state and the levels of resistance to commercially available insecticide formulations were measured on painted and unpainted plywood panels. Dimethoate was ineffective on all surfaces. The wettable powder permethrin formulation was more toxic than the emulsifiable concentrate formulation. The wettable powder cyfluthrin formulation was also more toxic than the recently developed liquid formulation. In general, the best house fly control was obtained on flat latex painted plywood panels and the poorest control on gloss latex painted panels. It is highly unlikely that producers obtain adequate control with dimethoate and permethrin.

Animals↗
PubMed2004

The contact toxicity of indoxacarb and five other insecticides to Orius insidiosus (Hemiptera: Anthocoridae) and Aphidius colemani (Hymenoptera: Braconidae), beneficials used in the greenhouse industry.

The contact toxicity of indoxacarb, abamectin, endosulfan, insecticide soap, S-kinoprene and dimethoate to Orius insidiosus (Say) and Aphidius colemani Viereck were studied in the laboratory. These beneficials are often used in the greenhouses to manage various insect pests. Indoxacarb is slow acting and therefore, to estimate lethal dosages, observations should be continued for several days until data stabilize. Seven days after treatment, the LC50 was 0.119 g AI litre(-1) for O insidiosus adults and 0.019 g AI litre(-1) for A colemani. At that time, the recommended field concentration was 0.479 times the LC50 for O insidiosus adults and three times the LC50 for A colemani. In contrast, indoxacarb had no adverse effect on the reproductive capacity of wasps surviving a treatment or the developing wasps in the aphid mummy. Among the other insecticides S-kinoprene was the most innocuous while dimethoate was the most toxic to the two beneficials. The other insecticides had overlapping toxicities.

Animals↗
PubMed1985

Occupational exposure to organophosphorus insecticides and synthetic pyrethroid.

Dermal and respiratory exposure to pirimiphosmethyl, dimethoate and permethrin were determined for applicators and operators in greenhouse tomato spraying operations. Dermal exposure is several times higher than the degree of respiratory exposure. Dermal exposure in terms of different parts of the body shows significant differences. For applicators the exposure of hands, arms and legs is the greatest, and the operators are the most exposed on their hands and to a small extent on legs. This fact should be taken into account when providing the workers with suitable protective clothing. The carefully selected technology of spraying also has great significance in decreasing the degree of exposure. Because of the chronic toxicity of dimethoate, all possible methods should be taken to reduce exposure.

Agricultural Workers' Diseases↗
PubMed1984

Susceptibility of ticks to acaricides in Zambia.

The susceptibility of some Zambian ticks to dieldrin, dioxathion, dimethoate and chlorfenvinphos was determined on two- to three-week-old larvae of Amblyomma variegatum, Boophilus decoloratus, B. microplus, Rhipicephalus appendiculatus, R. e. evertsi and a member of the R. pravus group. Some strains of B. decoloratus and R. appendiculatus were resistant to dieldrin, dioxathion and dimethoate and some R. e. evertsi were resistant to dieldrin and dioxathion. A single strain of an R. pravus group tick was resistant to dioxathion and one out of four strains of A. variegatum was resistant to dieldrin.

Animals↗
PubMed2004

Effects of pesticides on human peripheral lymphocytes in vitro: induction of DNA damage.

Because of the widespread use of pesticides for domestic and industrial applications the evaluation of their genotoxic effects is of major concern to public health. Although various experimental data have provided evidence that pesticides can possess genotoxic properties in animals and in in vitro test systems after acute and chronic exposure, the information on the genotoxic effects of some of pesticides is limited and inconsistent. In the present study, the genotoxic potential of commonly used pesticides (i.e., dimethoate and methyl parathion from the organophosphate class, propoxur and pirimicarb from carbamates, and cypermethrin and permethrin from pyrethroids) have been evaluated. The genotoxic effects of these substances were examined using the single cell gel electrophoresis (comet) assay in freshly isolated human peripheral lymphocytes. The cells were incubated with 10, 50, 100 and 200 microg/ml concentrations of the test substances for 0.5 h at 37 degrees C and DNA damage was compared with that obtained in lymphocytes from the same donor not treated with substances. Hydrogen peroxide, 100 microM, was used as a positive control. Within the concentration ranges studied, no significant cytotoxic effects were observed. Dimethoate and methyl parathion at 100 and 200 microg/ml; propoxur at 50, 100 and 200 microg/ml, and pirimicarb, cypermethrin and permethrin at 200 microg/ml significantly increased DNA damage in human lymphocytes.

Adult↗
PubMed2006

Ultrasound-assisted extraction of pesticides from olive branches: a multifactorial approach to method development.

A rapid and simple method has been developed for the analysis in olive branches of two insecticides currently used in olive pest control, dimethoate and alpha-cypermethrin. The effects of analytical conditions on pesticide recovery and the optimal extraction conditions were evaluated by means of a factorial design. The use of this chemometric tool in analytical method development allows the identification of the principal and interaction effects of the extraction conditions on the recovery of pesticides. It also gives information about the location of pesticide maximum recovery with minimal experimental investment. Extraction was carried out with an ultrasonic bath and the experimental conditions studied included the volume of extractant, the time of extraction, the number of extraction steps and the sample weight. The sample was further cleaned up using a Florisil solid-phase extraction cartridge. For the overall extraction procedure, recoveries of 99 % for alpha-cypermethrin and 90 % for dimethoate from the spiked samples were found for 1 g of sample extracted three times with 35 mL hexane, sonicating for 2 min in each step. The complete process including ultrasonic extraction and filtration will not require more than 15-20 min, in contrast with several hours for conventional liquid-solid extraction techniques. The proposed method allows a high sample throughput, as commonly required in monitoring studies.

Calibration↗
PubMed2005

Insecticides and arable weeds: effects on germination and seedling growth.

The decline of many arable weed species in Northern Europe has been attributed to the intensification of modern agriculture and in particular, increasing pesticide use. In this study, we examined the effect of two insecticides, dimethoate and deltamethrin, on the germination and seedling growth of six arable weed species. Although germination was unaffected by insecticide application, seedling growth of four species was decreased by exposure to deltamethrin (Capsella bursa-pastoris and Poa annua), dimethoate (Agrostemma githago), or by both insecticides together (Urtica urens). While increased herbicide use, seed cleaning, and changing sowing times may be of primary importance in explaining the reduction of northern Europe's arable weed flora, our results indicate that insecticide use may also be a contributory factor. Moreover, those species that exhibit apparent tolerance of the insecticides tested, particularly the grass Avena fatua, may benefit from continued insecticide use. The ability to tolerate these agrochemicals, in tandem with reduced herbivory and competition from plants, whose growth is reduced by insecticide application, is likely to confer a significant competitive advantage on insecticide-resistant weed species.

Agriculture↗
PubMed1984

Metabolic changes induced by organophosphates in the piscine organs.

Two common fish of commercial importance viz., Channa punctatus and Heteropneustes fossilis were exposed to sublethal concentrations of malathion and dimethoate (rogor). The exposure to malathion showed a gradual decrease in glycogen content in the liver and kidney of C. punctatus whereas the cholesterol level was increased. The protein content decreased initially, but thereafter a gradual increase was observed. However, in the exposure of H. fossilis to dimethoate, there was an increase in the glycogen content both in the liver and kidney during the second week. Thereafter a decrease was noted. The protein content showed insignificant changes. The specific activity of SDH showed a sharp rise initially for 2 weeks followed by a steep decline in both the tissues. The significance of these results are discussed in light of piscine metabolism.

Animals↗
PubMed1985

Effect of new organophosphates on the membrane of identified central neurons of Helix pomatia L. (Mollusca, Gastropoda).

Effects of two newly synthesized organophosphates were studied on identified neurons of Helix pomatia by microelectrophysiological methods. The single intracellular spikes were processed by computer using a "phase-plane trajectory" method. Dimethoate was also involved as reference substance. The mechanism of action of the substance NE-79297 was found to be similar to that of dimethoate resulting in prolongation of action potentials due to a delayed rectification of the outward current. Phosmethylan (NE-79168), a much more selective compound, altered the membrane parameters in a different way: it affected the slow--mainly calcium-mediated--inward current.

Action Potentials↗
PubMed2006

Evaluation of the effects, on canopy arthropods, of two agricultural management systems to control pests in olive groves from north-east of Portugal.

This study aims to investigate the effect of management regime on canopy arthropod community of the olive tree (Olea europaea L.). Field studies were performed in two successive years, 2002 and 2003, in two olive groves, one under organic farming and the other under integrated protection. The integrated protection grove was sprayed once a year in June, with dimethoate, to control the anthophagous generation of the olive moth, Prays oleae (Bern.). From April to November of each year, the canopy arthropods were sampled weekly. PRC method was used to analyse the effect of management regime at the community level and results showed that taxa responded differently to insecticide application suggesting that the organic grove was a more suitable habitat for the arthropods than the integrated protection grove. Abundance of arthropods peaked in May and June for both years but, after spraying with dimethoate, decreased significantly in integrated protection grove, recovering very slowly thereafter. Psocoptera, Miridae, Formicidae and Coccinellidae were the most sensitive taxa to insecticide application. Their decreasing in abundance was more evident in the second year of the trial. On the other hand chrysopids showed some tolerance to insecticide applications. These results suggest that the timing of spray is of utmost importance in reducing the side effects of spraying on beneficial arthropods. Moreover, differences in population susceptibility as well as in life cycle patterns must be considered.

Agriculture↗
PubMed2005

Terrestrial avoidance behaviour tests as screening tool to assess soil contamination.

To assess soil quality and risk assessment, bioassays can be useful tools to gauge the potential toxicity of contaminants focusing on their bioavailable fraction. A rapid and sublethal avoidance behaviour test was used as a screening tool with the earthworm Eisenia andrei and the isopod Porcellionides pruinosus, where organisms were exposed during 48 h to several chemicals (lindane, dimethoate and copper sulphate, for isopods and carbendazim, benomyl, dimethoate and copper sulphate for earthworms). Both species were also exposed to soils from an abandoned mine. For all bioassays a statistical approach was used to derive EC50 values. Isopods and earthworms were able to perceive the presence of toxic compounds and escaping from contaminated to clean soil. Furthermore the behaviour parameter was equally or more sensitive then other sublethal parameters (e.g. reproduction or growth), expressing the advantages of Avoidance Behaviour Tests as screening tools in ERA.

Animals↗
PubMed1998

Organic trace compounds in the water of the River Elbe near Hamburg. Part II.

Part II of the quantitative determination of altogether 145 distinct organic compounds is presented (88 organic compounds). Elevated amounts of some pesticides concerning triazines and especially dimethoate were recorded as well as of O,O,O-trimethylthiophosphate and O,O,S-trimethyldithiophos-phate, which are related to the chemistry of dimethoate. A comparison of the results of PCB-quantification in unfiltered water samples with the results for solid phase material (SPM-phase) in river water is presented. The occurrence of organic trace compounds in the River Elbe is discussed in comparison to corresponding investigations of the River Rhine.

Dimethoate↗
PubMed2002

Monitoring of pesticide residues in Egyptian fruits and vegetables during 1997.

A total of 2318 domestic samples of different types of fruits and vegetables were collected from eight Egyptian local markets in six different regions of the country. All samples were examined for residues of 54 pesticides, including organophosphorus, organonitrogen, organohalogen and certain pyrethroides. However, dithiocarbamates were analysed in only 318 samples. Overall, 81.5% of the samples had no detectable pesticide residues. Of the contaminated samples, 18.5% contained detectable residues and 1.9% exceeded their maximum residue limits (MRLs). Root and leafy vegetables showed the lowest contamination rates (1.9 and 4.7%, respectively), slightly exceeding the MRLs in leafy vegetables. However, fruit samples showed a slightly higher proportion of contamination than vegetables (29 and 14.3%, respectively). Fruit also exhibited a higher level of violation than vegetables (2.3 and 1.9%, respectively). The contamination and violation rates were lower than the percentages recorded in previous years' monitoring studies. Dicofol and dimethoate were the most frequently occurring pesticide residues at 5.1 and 5.0%, respectively. Dimethoate showed higher violation levels (0.69%). However, dicofol showed a slight violation rate (0.09%) which indicates good agricultural practices for dicofol use. Dithiocarbamates residues were found in 21 of the 318 samples analysed, which when expressed as a percentage contamination was 6.6%, and only one sample exceeded the MRL.

Chromatography, Gas↗
PubMed1989

In vivo studies on the effect of some insecticides on the hepatic activities of L-tryptophan 2,3-dioxygenase and pyridoxal phosphokinase of male mice.

The effect of Dimethoate, Carbaryl and Permethrin on the activities of liver L-tryptophan 2,3-dioxygenase (total-, holo-, and apo-forms) and pyridoxal phosphokinase of male mice was investigated. Dimethoate inhibited both enzyme systems after single and repeated dose treatment; except the dioxygenase holo-enzyme after repeated doses. Single dose of Carbaryl treatment inhibited the pyridoxal phosphokinase, total and holo-enzyme of L-tryptophan dioxygenase. However, the repeated dose treatment do not affect both enzyme systems. Permethrin inhibited only total-, holo- and apo-enzymes of L-tryptophan dioxygenase whereas repeated administration has no significant effect on both enzymes. The data indicate that these insecticides may induce abnormal tryptophan metabolism through which some endogenous bladder carcinogens are formed.

Animals↗
PubMed1990

A field study on residues of four insecticides used in strawberry protection.

In 1986 strawberry plots were treated with dimethoate, malathion, permethrin and cypermethrin at 80% bloom of primary flowers. In 1987 the plots were sprayed with dimethoate, malathion and permethrin at 30% bloom. Residue analysis of these insecticides on the flowers were analyzed using solvent extraction and gas liquid chromatography. Residue analysis at 0 to 18 days on flowers and fruit showed an exponential decrease. Organophosphates tended to degrade more quickly than synthetic pyrethroids. The results are discussed in the context of an integrated pest management program.

Animals↗
PubMed1990

Effects of pesticides on filth fly predators (Coleoptera: Histeridae, Staphylinidae; Acarina: Macrochelidae, Uropodidae) in caged layer poultry manure.

A field study on two caged layer poultry operations assessed whether selected pesticides would affect beneficial predators. Sampling was done three times during the 5-wk period before treatment, 3 d after each of two weekly treatments, and 5-6 times during the 10 wk after the second treatment. Cyromazine (0.1%) applied topically had no detrimental effect on any of the predator taxa. Dimethoate (0.5%) applied as a spot treatment to wet areas of the manure also did not reduce predator abundance. Permethrin (0.05%) applied as a direct treatment to the hens resulted in slight reductions in numbers of Histeridae and Staphylinidae in the manure. A resurgence of Fanniinae occurred at one site 3 wk after permethrin application. Treatment of whole houses with dimethoate (0.5%) resulted in short-term reductions (up to 3 wk) of predatory mites and reductions of Histeridae and Staphylinidae for 4-10 wk.

Animals↗