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PubMed2001

Impact of doramectin treatment at the time of feedlot entry on the productivity of yearling steers with natural nematode infections.

OBJECTIVE: To measure the reduction in fecal nematode egg counts and productivity impact of treatment of yearling steers with doramectin at entry into the feedlot, compared with control steers treated only with fenthion. ANIMALS: 6,096 crossbred yearling steers with a mean (+/- SD) body weight of 377.0 (+/- 37) kg. PROCEDURE: Steers were implanted with zeranol and alternately separated to fill each of 24 pens. Groups of steers within 12 matched pairs of pens were randomly allocated to treatment with doramectin or no treatment with doramectin for internal nematodes. Fecal samples were collected from approximately every twentieth steer from each pen at day 0 and at reimplant (approx day 60). Each steer was weighed on day 0 and at reimplant and then mean body weights of steers per pen were determined at 120 to 140 days after trial initiation. RESULTS: Treatment steers had a significantly lower fecal egg count at reimplant than control steers. Treatment steers had a significantly greater mean daily gain during the study, significantly greater feed consumption, significantly lower feed-to-gain ratio, and significantly better quality carcass grades at slaughter. CONCLUSIONS AND CLINICAL RELEVANCE: Under the conditions of our trial, there was a significant fecal egg count reduction response to doramectin treatment, which resulted in significantly improved productivity. Results of economic analysis of return on investment indicated that even with low egg counts in heavy body weight cattle, nematode egg count reduction with doramectin significantly improved returns.

Anabolic Agents↗
PubMedDate not supplied

Safety comparison of insecticide microencapsulation and investigation of its mechanism.

Four kinds of microencapsulated insecticides were prepared with fenthion, mevinphos, acetofenate and methylparathion. From observations made after the experiment it was found that type II microcapsules with polyurea capsule walls formed by interfacial polymerization had a special advantage: they had greatly enhanced safety in mice when administered via mouth, respiratory tract and skin. Type I microcapsules, with capsular walls of gelatin and Arabic gum formed through complex condensation, had no safety protection with oral administration. The mechanism of safety enhancement associated with type II microcapsules depends mainly on maintenance of microcapsule integrity within the digestive tract; type II microcapsules rarely disintegrated in the gastrointestinal tract and only about 5 per cent were ruptured. Of the small quantity of insecticide that leaked through the ruptured capsule walls, the amount absorbed by the digestive tract was not sufficient to kill the mice before the microcapsules were discharged in faeces--The amount of discharge within 48 hours exceeded 80 per cent. Administration of large numbers of microcapsules was necessary before sufficient insecticide could be absorbed by the digestive tract to cause lethal dosage; on post-mortem examination some microcapsules were found intact in the stomach and small intestine. Type I microcapsules, however, were totally disintegrated in the digestive tract and no traces could be found in the faeces; therefore their drug safety could not be increased.

Accident Prevention↗
PubMed1992

Epidemio-entomological survey on malarial vector mosquitoes in Kyongbuk, Korea.

In order to determine population dynamics of Anopheles sinensis, a survey based on average number of female mosquitoes per trap-night was carried out during the period of 5 years from 1987 to 1991. A. sinensis first appeared between the 2nd and 20th April, and were trapped in large number between the 5th and 12th July. The number of trapped mosquitoes began to decrease from mid-August, and a few were collected until mid-November, each year. The average number of A. sinensis in July was 542.6 per trap-night in 1987, but in 1989 increased abruptly to 1,331.4, and then decreased to considerably lower levels, 271.9 in 1990 and 372.1 in 1991. The nocturnal activity of A. sinensis to attack humans was found to become active in the early night, and it was gradually decreasing at mid-night, however, then slightly increasing toward dawn. The immature stage of A. sinensis in the rice paddies was first found in the correlation pattern with peak adult densities in early July. The highest larval density of A. sinensis in the study area was 21,226 x 10(3) in early July 1990. The larval A. sinensis showed high resistance level and resistance ratios against 3 kinds of organo-phosphorous compounds, diazinon, malathion, and fenitrothion, but low resistance against fenthion. The present results indicated that the population density of A. sinensis in Kyongbuk area is decreasing over the five-year from 1987 to 1991.

Adolescent↗
PubMed1984

Cost-benefit evaluation of house fly (Diptera:Muscidae) control in caged layer poultry houses.

House fly (Musca domestica L.) control was determined in small-unit, commercial, caged layer poultry houses. Cyromazine was the most cost effective treatment (4 per bird per season) and provided the highest level of control. Larviciding and adulticiding with dimethoate, fenthion and dimethoate, permethrin and dimethoate, and stirofos provided good fly control, and these treatments were moderately cost effective. The use of dichlorvos-stirofos provided only marginal fly control and was not cost effective. Early-season manure removal, combined with more selective insecticide use would provide the caged layer producer with a more effective management strategy for controlling house flies in small-unit operations.

Animals↗
PubMed2004

Pesticide poisoning events in wild birds in Korea from 1998 to 2002.

We describe cases of pesticide poisoning of wild birds diagnosed at the National Veterinary Research and Quarantine Service (Kyunggi, Korea) from 1998 to 2002. Forty-one mortality events (759 birds) of 87 incidents (2,464 birds) investigated were associated with pesticide poisoning, and six organophosphates or carbamates were identified as being responsible for the poisoning. Phosphamidon was most frequently identified as the cause of poisoning, accounting for 23 mortality events. Other pesticides identified as poisons for birds were organophosphates monocrotophus, fenthion, parathion, EPN, and diazinon, and the carbamate carbofuran. Pesticide poisoning is a problem in wild birds in Korea.

Animals↗
PubMedDate not supplied

[Research on some phosphorganic insecticide residues in olive oil in relation to techniques of Dacus oleae control. I. Results of total treatment to the foliage (author's transl)].

The research conducted to verify the presence and the amount of residues of organophosphorus insecticides in olive oil from olive trees sprayed against. Dacus oleae has shown that both hydrophilic (dimethoate, formathion, phosphamidon) and lypophilic (fenthion, medathion, prolate) substances tested leave more or less appreciable residues in the oil, either in a short time or in more than one month from the treatment. In the operative conditions reflecting antidacic practice, the amount of residue appears higher for the lypophilic organophosphorus insecticides.

Food Contamination↗
PubMed1975

Inheritance of resistance to organophosphorus insecticides in Culex tarsalis Coquillet.

The mode of inheritance of resistance to parathion, fenitrothion, fenthion, chlorpyr fosmethyl, and parathion-methyl was studied in a strain of C. tarsalis. Resistance in the F(1) hybrid was partially dominant. Backcross experiments indicated that resistance is derived from more than one gene. This conclusion was confirmed by repeated backcrosses of the F(1) to the susceptible strain and selection of the backcross progeny with a discriminating dosage of parathion-methyl.

Animals↗
PubMedDate not supplied

New method for determination of ten pesticides in human blood.

An analytical method was developed for precise identification and quantitation of 10 pesticides in human blood. The pesticides studied, which have appeared frequently in actual cases, were endosulfan, lindane, parathion, ethyl-azinphos, diazinon, malathion, alachlor, tetradifon, fenthion and dicofol (o-p' and p-p' isomers). The current method replaces an earlier method which involved liquid-liquid extraction with a mixture of n-hexane-benzene (1 + 1). The extraction is performed by solid-phase extraction, with C18 cartridges and 2 internal standards, perthane and triphenylphosphate. Eluates were analyzed by gas chromatography (GC) with nitrogen-phosphorus and electrochemical detectors. Results were confirmed by GC-mass spectrometry in the electron impact mode. Blood blank samples spiked with 2 standard mixtures and an internal standard were used for quantitation. Mean recoveries ranged from 71.83 to 97.10%. Detection and quantitation limits are reported for each pesticide. Examples are provided to show the application of the present method to actual samples.

Calibration↗
PubMedDate not supplied

Gas chromatography with pulsed flame photometric detection multiresidue method for organophosphate pesticide and metabolite residues at the parts-per-billion level in representatives commodities of fruits and vegetable crop groups.

A gas chromatographic method with a pulsed flame photometric detector (P-FPD) is presented for the analysis of 28 parent organophosphate (OP) pesticides and their OP metabolites. A total of 57 organophosphates were analyzed in 10 representative fruit and vegetable crop groups. The method is based on a judicious selection of known procedures from FDA sources such as the Pesticide Analytical Manual and Laboratory Information Bulletins, combined in a manner to recover the OPs and their metabolite(s) at the part-per-billion (ppb) level. The method uses an acetone extraction with either miniaturized Hydromatrix column partitioning or alternately a miniaturized methylene dichloride liquid-liquid partitioning, followed by solid-phase extraction (SPE) cleanup with graphitized carbon black (GCB) and PSA cartridges. Determination of residues is by programmed temperature capillary column gas chromatography fitted with a P-FPD set in the phosphorus mode. The method is designed so that a set of samples can be prepared in 1 working day for overnight instrumental analysis. The recovery data indicates that a daily column-cutting procedure used in combination with the SPE extract cleanup effectively reduces matrix enhancement at the ppb level for many organophosphates. The OPs most susceptible to elevated recoveries around or greater than 150%, based on peak area calculations, were trichlorfon, phosmet, and the metabolites of dimethoate, fenamiphos, fenthion, and phorate.

Acetone↗
PubMedDate not supplied

Determination of insecticides in honey by matrix solid-phase dispersion and gas chromatography with nitrogen-phosphorus detection and mass spectrometric confirmation.

A multiresidue method was developed for the determination of 12 organophosphorus insecticides (diazinon, parathion methyl, fenitrothion, pirimiphosmethyl, malathion, fenthion, chlorpyrifos, quinalphos, methidathion, ethion, azinphosmethyl, coumaphos), one carbamate (pirimicarb), and one amidine (amitraz) in unifloral and multifloral honeys. The analytical procedure was based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and subsequent extraction with a low volume of hexane-ethyl acetate (90 + 10, v/v), assisted by sonication. The insecticide residues were determined by capillary chromatography with nitrogen-phosphorus detection and confirmed by mass spectrometry. Average recoveries at the 0.05-0.5 microg/g levels were >80% for organophosphorus insecticides and about 60% for the other insecticides, pirimicarb and amitraz, with relative standard deviations <10%. The detection limit for the different insecticides ranged between 6 and 15 microg/kg. The main advantages of the proposed method are that extraction and cleanup are performed in a single step with a low volume of organic solvent. The method is simple, rapid, and less laborious than conventional methods. Several Spanish honeys were analyzed with the proposed method and no residues of the studied insecticides were found.

Gas Chromatography-Mass Spectrometry↗
PubMed1975

Chemotherapeutic studies on Litomosoides carinii infection of Mastomys natalensis. 6. The filaricidal activity of organophosphorus compounds.

Several organophosphorus compounds have been evaluated for their efficacy against micro- and macrofilariae in experimental investigations on Litomosoides carinii infection in the multimammate rat Mastomys natalensis. The anthelmintic haloxon proved to be the most effective compound with high activity against microfilariae and a favourable chemotherapeutic range. The organophosphates fenthion, Dursban, metrifonate, coumaphos, crufomate and naphthalophos also showed pronounced microfilaricidal activity but with different and lower chemotherapeutic indices. The preparations chlorfenvinphos, benoxafos, cythioate and imidan proved to be without marked microfilaricidal action at tolerable dose schedules. The organophosphorus compounds did not show any influence on the mobility or viability of the adult worms of Litomosoides carinii.

Animals↗
PubMed1992

Are Wistar rats not susceptible to organophosphate-induced delayed neurotoxicity?

Male Wistar rats were sacrificed 12 weeks after single exposure to various organophosphate compounds. Peripheral nerves and skeletal muscles were examined light microscopically for the occurrence of a delayed polyneuropathy. Although unequivocal morphological hallmarks of OPIDN had been demonstrated in other rat strains using similar doses of TOCP or mipafox, we were unable to demonstrate any abnormality with these compounds. Normal findings were also obtained with fenthion, the delayed neuropathic potential of which is debated, and with paraoxon or parathion, which are both highly unlikely to cause OPIDN. These data indicate that the Wistar rat strain is highly likely to be resistant to OPIDN.

Animals↗
PubMed1963

The toxicity of some organophosphorus compounds to adult Anopheles stephensi.

The authors have evaluated a number of organophosphorus compounds for residual contact toxicity to adult Anopheles stephensi. Fenthion and malathion were the most promising of the compounds, and wettable powder deposits at a dosage of 1 g/m(2) on plywood remained effective for five months. There was, however, a rapid loss of effectiveness on dried mud bricks stored at 25 degrees C and 50%-55% relative humidity.Diazinon and ronnel were less persistent on plywood. Guthion and coumaphos, although highly toxic by topical application, were both ineffective as contact insecticides when applied as solids in suspension. Trithion and methyl trithion were relatively low in toxicity both by topical application and as contact insecticides.

Animals↗
PubMed1962

The susceptibility of Culex pipiens fatigans to residual insecticides with particular reference to the Taveta-Pare area of East Africa.

Observations have been made on Culex pipiens fatigans in the Taveta-Pare area in East Africa from 1954 to 1961, during which time dieldrin was applied to local houses over a 3(1/2)-year period as part of an experiment in malaria control. At the end of the period of residual spraying the numbers of C. p. fatigans had been reduced by two-thirds in the Taveta area, but in the South Pare area, only some 160 km away, this mosquito was twice as numerous as before spraying. The results of susceptibility tests carried out in untreated and dieldrin-treated areas showed that the susceptibility of C. p. fatigans in East Africa to chlorinated hydrocarbon insecticides was low compared with that of Anopheles gambiae, and varied by at least 20 times in some areas relatively short distances apart. C. p. fatigans from all areas sampled were, however, susceptible to fenthion and malathion.

Africa, Eastern↗
PubMed1992

Seasonal incidence and horizontal distribution patterns of oviposition by Aedes aegypti in an urban environment in Trinidad, west Indies.

The oviposition patterns of Aedes aegypti in ovitraps placed along 5 horizontal transects were monitored weekly for 52 wk (January to December 1988) in St. Joseph, Trinidad. Of the 2,550 ovitraps exposed, 270 were lost and 1,177 (52%) out of 2,280 were used by gravid females, containing 38,118 eggs. During the dry season 43% (16,265 eggs) of the eggs were collected whereas during the wet season 57% (21,853 eggs) were collected. Ovitraps exposed under eaves, under houses and in the open yard attracted similar oviposition occurrences and proportions of eggs. Inspections of the 52 properties within St. Joseph revealed that 17 (House Index = 32.7%) harbored Ae. aegypti pre-adult stages. The container index was 5.5%. This study revealed no evidence of behavioral changes in the container preferences of Ae. aegypti in St. Joseph, Trinidad, after 12 years of treating with fenthion and temephos.

Aedes↗
PubMedDate not supplied

Evaluation of pirimiphos-methyl (50% EC) against the immatures of Anopheles stephensi/An. culicifacies (malaria vectors) and Culex quinquefasciatus (vector of bancroftian filariasis).

BACKGROUND & OBJECTIVES: In India, temephos and fenthion are used as larvicides in fresh and polluted waters. Since use of same insecticide may precipitate resistant, as an alternative bioefficacy of pirimiphos-methyl--an organophosphorus insecticide was evaluated against immatures of Anopheles and Culex species in different breeding habitats in District Ghaziabad (U.P.) and Goa. METHODS: Laboratory bioassays were carried out using standard WHO procedure. LC50 and LC90 were calculated using Probit analysis. Abbott's formula was used to calculate per cent corrected mortality in laboratory exposures while, Mulla's formula was applied for calculating per cent reduction in mosquito immatures under field conditions. RESULTS: Pirimiphos-methyl was found to be most effective against larvae of An. stephensi followed by An. culicifacies and Cx. quinquefasciatus. The LC50 and LC90 values against three species were 0.023, 0.032 and 0.04 ppm; and 0.045, 0.057 and 0.114 ppm respectively. In field, pirimiphos-methyl @ 200 g a.i./ha against Anopheles species and @ 300 g a.i./ha against Culex species can produce > 80% reduction in density of immatures up to one week in different habitats. Pirimiphos-methyl < 0.25 ppm is not toxic to fish. INTERPRETATION & CONCLUSION: Pirimiphos-methyl is more effective against anophelines in clean water than culicines in polluted water. This larvicide should not be used at a concentration above 0.25 ppm in habitats harbouring the larvivorous fish.

Animals↗
PubMed2003

Susceptibility status of Japanese encephalitis vectors in Kurnool and Mehboobnagar districts of Andhra Pradesh, India.

An entomological survey in Kurnool and Mahboobnagar districts of Andhra Pradesh state, India was undertaken in January, 2002 to find out vector population of Japanese Encephalitis and their susceptibility status to different insecticides. Five Culicine species viz. of Cx. tritaeniorhynchus, Cx. vishnui, Cx. pseudovishnui, Cx. bitaeniorhynchus, Cx. gelidus were captured during the survey. Another suspected vectors Anopheles subpictus and An. hyrcanus were also prevalent in the study villages. The larval population showed a high degree of resistance to Fenthion and Temephos. The test mortality to DDT ranged between 75% and 90%. The mortality of Cx. tritaeniorhynchus, Cx vishnui and An. subpictus ranged from 85% to 95%. Cx. tritaeniorhynchus is susceptible to Deltamethrin and Cyfluthrin. Cx. vishnui showed 80 % and 85% mortality to DDT and Malathion respectively.

Animals↗
PubMedDate not supplied

[Levels of resistance to insecticides and their mechanisms in 2 strains of Aedes aegypti from Panama].

The levels of susceptibility and/or resistance to insecticides in larvae and adults of Aedes aegypti from 2 localities of Panama (Rio Abajo and Victoriano Lorenzo) were determined. Among larvae, it was found resistance to methyl- pyrimifos in both localities; however, they were susceptible to the rest of the organophosphate insecticides (temephos, malathion, fenthion fenitrothion and clorpirifos) and to pyrethroids (deltamethrin, lambda-cyhalothrin, cypermethrin and cyfluthrin. In the trials carried out in adults, according to the categories of the World Health Organization, the 2 localities proved to be completely susceptible to deltamethrin, lambda-cyhalothrin, beta cypermethrin and cyfluthrin.

Aedes↗