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PubMedDate not supplied

[Susceptibility of the horn fly (Haematobia irritans) to insecticides in the Tabuleiros Costeiros region in states of Alagoas, Bahia and Sergipe, Brazil].

Susceptibility of horn fly populations to insecticides was evaluated at the Tabuleiros Costeiros region in the states of Alagoas, Bahia, and Sergipe from April 2001 to December 2002. A total of 37 bioassays were conducted in 23 ranches from 12 municipalities. Fly susceptibility was determined by the impregnated filter paper method using the active ingredients diazinon, permethrin, and cypermethrin. A high susceptibility to diazinon was found, with LC50 varying from 0.23 to 1.41 microg/cm2 and resistance ratios (RR) = 1.3. On the other hand, resistance to pyrethroids was detected in all studied populations. Cypermethrin LC50 ranged from 19.94 to 1,928 microg/cm2 and RR from 21.2 to 4,484.4. Although resistance levels to permethrin were much lower (RR<6), all LC50 were significantly higher than the LC50 obtained from the susceptible population. All ranches relied on pyrethroids for horn fly control, most cypermethrin (88.46%) and deltamethrin (80.77%) products. Spraying, by using manual backpack sprayers, was routinely used in all ranches. History of insecticide use as well as inadequate control practices help to explain the spread resistance of horn fly populations to pyrethroids detected in the region.

Animals↗
PubMed1991

Crusted (Norwegian) scabies.

Crusted (Norwegian) scabies, a rare variant of ordinary scabies, is a highly contagious infection in which the skin is infested with thousands to millions of mites. The infection is frequently overlooked because of its atypical presentations. Patients with cognitive deficiency or an immunodeficiency disorder (including immunosuppressive therapy) are predisposed to developing crusted scabies. The infection often presents as generalized dermatitis with crusted hyperkeratosis on the palms and soles. Diagnosis is made by examining skin scrapings from the crusted lesions. Lindane is the scabicide most widely used in the treatment of crusted scabies. Eradication frequently requires repeated applications, and care must be taken to avoid lindane toxicity. Permethrin cream is as efficacious as lindane in the treatment of ordinary scabies. Because of its wider margin of safety, permethrin may become the preferred treatment for crusted scabies.

Hexachlorocyclohexane↗
PubMed1986

Gambian cultural preferences in the use of insecticide-impregnated bed nets.

In field trials of permethrin-treated bed nets in a large Mandinka village, 95% of people were already sleeping under locally-made nets. They lasted about 6 years and cost about US$9.00 ($1.50 per year). Two permethrin dips per year added a further $0.60 per year (1985 prices). Non-immune children slept in beds shared with adults, and people wanted nets for many reasons, not just malaria protection. Fifty-eight per cent of people preferred opaque sheeting to open netting; sheeting gave more privacy, lasted longer, gave better protection from very small insects, dust, rats, etc. White was the colour preferred by 90% of interviewees. Comparing Mandinka with Wolof and Fula, there were ethnic differences in net owning and the proportion of children sleeping in beds with a mattress.

Adult↗
PubMed1984

Control of Boophilus ticks on heifers with two pyrethroids applied as sprays.

The pyrethroid permethrin (25% cis to 75% trans) was sprayed on Hereford heifers infested with all parasitic stages of Boophilus microplus (Canestrini) at 0.05% and 0.1% active ingredient. At 0.05%, control was 66.7%; whereas at 0.1%, control was 93.3%. Replete females were collected daily for 28 days after treatment at both concentrations, indicating that at least some ticks treated as larvae or nymphs were able to reach repletion. The pyrethroid fenvalerate was sprayed on Hereford heifers infested with all parasitic stages of B microplus or B annulatus (Say) at 0.025% and 0.05% active ingredient. Fenvalerate was as effective as permethrin at a lower concentration. At 0.025%, control was 89.2% and 86.6% and at 0.05% was 92.5% and 90.1% for B microplus and B annulatus , respectively. Both these pyrethroids could provide adequate reduction in programs in which control is the aim; however, in an eradication program, both acaricides failed to provide the necessary reduction to achieve complete elimination.

Animals↗
PubMed1995

[Inhibition of glutamate uptake in rat brain synaptosome by pyrethroids].

In vitro studies showed deltamethrin (1 x 10(-7)-1 x 10(-4) mol/L) could inhibit 3H-DL-glutamate uptake in rat cerebral cortex and hippocampus synaptosome by 7.2%-21.5% and 10.4%-25.1%, respectively, with a dose-response pattern. But only in high-dose permethrin (1 x 10(-4) mol/L) can significantly reduce 3H-DL-glutamate uptake in rat hippocampus synaptosome. In addition, deltamethrin also can reduce 3H-DL-glutamate uptake in cerebellum and striatum of rats by 16.5% and 31.8%, respectively. It is suggested that both deltamethrin and permethrin, especially the former, can disturb the function of brain tissue in high-affinity-glutamate uptake with their alpha-cyano-group. So pyrethroids could play an important role in cerebral stimulation in mammals.

Animals↗
PubMed1993

Susceptibility difference in two populations of Culex quinquefasciatus Say (Diptera: Culicidae) to three synthetic pyrethroids.

Three synthetic pyrethroids were tested for their efficacy against two populations of the filariasis vector Culex quinquefasciatus under laboratory conditions following the WHO procedure, Emulsifiable concentration and technical grade formulations of deltamethrin (2.5% wp), cypermethrin (1.0% EC) and permethrin (25% EC) were employed on the larvae of the said species collected from Mysore and Mandya. All the three pyrethroids were found to be effective. But among the three, deltamethrin was found to be the most effective and cypermethrin was more efficient than permethrin. Mysore species were found to be more susceptible than the Mandya population to all the chemicals tested though they are separated by hardly 50 km.

Animals↗
PubMedDate not supplied

Synergized pyrethrin mousse, a new approach to head lice eradication: efficacy in field and laboratory studies.

The purpose of this study was to evaluate the pediculicidal and ovicidal efficacy of a new, single-application formulation of synergized natural pyrethrins (presented in an aerosol mousse form) compared with an established, effective formulation based on permethrin (in a creme rinse form). The trial was a single-blind, comparative, randomized, parallel-group study. Children between the ages 7 and 15 years and adults with active head lice infections, identified by the presence of live lice, were enrolled from a school and a children's home in Dhaka, Bangladesh. Prevalence of infection ranged from 75% to 100% in the two study centers. The field study confirmed laboratory findings showing pyrethrin mousse to be effective at killing both lice and their eggs with a single 10-minute application. Of 52 patients identified with lice, 42 were treated with pyrethrin mousse and 10 with permethrin creme rinse. In each case, a sample of viable louse eggs was taken from the patients' hair before and after treatment. The eggs were then incubated to assess ovicidal activity. After treatment, the patients were examined for lice on alternate days until day 8 and then again on day 14. None of the patients in either group was found to have lice up to 2 days after treatment. One patient was found to have two moribund hatchlings on day 4. By day 6, when any eggs still present on the scalp would be expected to hatch, 19 pyrethrin mousse-treated patients were available for assessment. Two patients had been reinfected from contacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1993

Compatibility of cyclopoid copepods with mosquito insecticides.

Larvivorous copepods (Macrocyclops, Mesocyclops and Acanthocyclops) were tested for their sensitivities to commonly used mosquito larvicides and adulticides. The cyclopoids were not harmed by Bacillus thuringiensis (H-14) (B.t.i.) or larviciding oil. Control of mosquito larvae in field trials was accelerated by applying B.t.i. at the same time cyclopoids were introduced to a breeding site. Among adulticides tested, the cyclopoids were least sensitive to permethrin. Field trials demonstrated that permethrin does not harm cyclopoids when applied at label specifications.

Animals↗
PubMed1996

Systemic application of pyrethroid insecticides evokes differential expression of c-Fos and c-Jun proteins in rat brain.

Expression of the c-Fos and c-Jun transcription factor was investigated by immunocytochemistry in the thalamus, hypothalamus, hippocampus and cortex of adult rats following intraperitoneal application of proconvulsant doses of the pyrethroid insecticides, cypermethrin and permethrin. Pyrethroid insecticides are used world-wide and their uptake, e.g., by nutrition and inhalation evokes severe neurological symptoms in animals and humans, but their effects on neuronal gene expression has not been elucidated. Cypermethrin induced a strong expression of c-Fos and c-Jun in all the thalamic nuclei, except the ventro-posterior complex and substantia nigra, and in all the hypothalamic nuclei. In general, the immunoreactivities (IR) persisted for 8 h on their maximal levels, and were still above control levels after 24 h in several thalamic and hypothalamic areas. c-Fos-IR was strongly increased in all cortical layers with a predominance in the superficial layers II-IV, whereas c-Jun-IR was only slightly increased. In the hippocampus, cypermethrin induced a weak expression of c-Fos, but not of c-Jun, in the dentate gyrus and CA-3 area. Permethrin that has a lower pharmacological potency, evoked a similar pattern of c-Fos and c-Jun expression, however, intensity and persistence of the neuronal labeling were less pronounced. Our results demonstrate that the neurotoxic effects of pyrethroid insecticides comprise molecular genetic alterations in the brain such as early and lasting induction of Fos and Jun transcription factor proteins. These changes in the neuronal program are prominent in the hypothalamus and thalamus that are involved in the regulation of the autonomic and visceral nervous systems.

Animals↗
PubMed1997

Pesticide avoidance behavior in Anopheles albimanus, a malaria vector in the Americas.

The behavioral responses of 4 populations of Anopheles albimanus females to DDT, permethrin, and deltamethrin were characterized in excito-repellency tests. One test population (ST) from El Salvador has been maintained as a colony for 20 years. A second population (ES) from Guatemala was colonized in 1992. Third and fourth populations consisted of field-caught specimens from Toledo District (TO) of southern Belize in 1994 and Corozal District (CO) of northern Belize, respectively. Females of ES, TO, and CO populations rapidly escaped from direct contact with treated surfaces for each of the 3 insecticides. Similarities in escape responses of insecticide-resistant (ES) versus insecticide-susceptible populations (TO, CO) suggest that there is no relationship between physiological and behavioral responses of An. albimanus populations to DDT, permethrin, and deltamethrin. Females from all but the ST colony escaped in greater numbers from chambers without direct contact with treated surfaces than from control chambers (P < 0.05). Few females from the ST colony escaped from test chambers, regardless of which insecticide was used or whether contact was allowed, indicating that the ST colony has lost its capability to respond to insecticides. Repellent responses were significant; but they were not pronounced in 30-min exposures, and they were very pronounced in 4-h exposures. We conclude that irritant and repellent responses of malaria vectors to insecticides are important components of malaria control operations.

Americas↗
PubMed2004

Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol.

OBJECTIVE: To compare the acaricidal activity of Melaleuca alternifolia (tea tree) oil (TTO) and some of its individual active components on the itch mite Sarcoptes scabiei var hominis. DESIGN: In vitro acaricide sensitivity assessment. SETTING: The Menzies School of Health Research laboratory, located near the Infectious Diseases Ward of the Royal Darwin Hospital, Australia, where patients are admitted and treated for crusted scabies. PARTICIPANTS: Scabies mites (S scabiei var hominis) were collected from a 20-year-old Aboriginal woman admitted to the Royal Darwin Hospital with crusted scabies. Interventions Within 3 hours of collection, scabies mites were placed in continuous direct contact with the TTO products and control acaricides and were observed at regular intervals. MAIN OUTCOME MEASURES: Percentage of mites dead at regular observation intervals between 5 minutes and 24 hours during continuous exposure to the TTO products and acaricides. RESULTS: The 5% TTO and active component terpinen-4-ol were highly effective in reducing mite survival times. Statistically significant differences in mite survival curves were observed for 5% TTO, 2.1% terpinen-4-ol, 5% permethrin, and ivermectin (100 microg/g of Emulsifying Ointment British Pharmacopoeia 88). In vivo effectiveness was also observed. CONCLUSIONS: Documentation of resistance against antiectoparasitic compounds is increasing. Reported S scabiei treatment failures with lindane, crotamiton, and benzyl benzoate, as well as likely emerging resistance to 5% permethrin and oral ivermectin, are of concern and advocate for the identification and development of novel acaricidal drugs. Tea tree oil is a membrane-active biocide extracted from the tree M alternifolia. It is a principal antimicrobial in a wide range of pharmaceuticals sold in Australia, with the main active component being oxygenated terpenoids. The results suggest that TTO has a potential role as a new topical acaricide and confirm terpinen-4-ol as the primary active component.

Adult↗
PubMed1987

Pyrethroid inhibition of basal and calmodulin stimulated Ca2+ ATPase and adenylate cyclase in rat brain.

Effects of two classes of pyrethroids, permethrin and resmethrin (type I), cypermethrin and deltamethrin (type II), on basal (calmodulin-deficient) and calmodulin stimulated activities of Ca2+ ATPase and adenylate cyclase from rat brain were studied in vitro. None of the pyrethroids inhibited synaptosomal basal Ca2+ ATPase, but permethrin and deltamethrin inhibited basal adenylate cyclase in the nuclear fraction of a brain homogenate. Both groups of pyrethroids decreased the calmodulin activated Ca2+ ATPase and adenylate cyclase from brain synaptosomes and nuclear fraction. The results indicate that calmodulin-stimulated Ca2+ ATPase is more sensitive to type II pyrethroids and pyrethroids are more effective on calmodulin stimulated enzymes than basal enzyme activities. Since calmodulin, adenylate cyclase and Ca2+ ATPase are known to participate in various brain processes, it is possible that pyrethroids alter neural transmission, however, additional in vivo work would be needed to confirm this possibility.

Adenylyl Cyclase Inhibitors↗
PubMed2006

7-Coumaryl permethrate and its cis- and trans-isomers as new fluorescent substrates for examining pyrethroid- cleaving enzymes.

New esterase substrates were synthesized using cis-, trans- and cis-trans-permethrinic acid chloride and then used to measure pyrethroid-cleaving enzymes in insects. The new substrates, namely cis-, trans- and cis-trans-7-coumaryl permethrates (7-CP), show a structure very similar to permethrin insecticide and yield fluorescent products on hydrolysis. These substrates were hydrolyzed by a commercial porcine preparation that provided esterase-specific activity, and were stable at different pH values (5.2-7.8). Studies made with house fly, Musca domestica (L.), homogenates showed that these compounds are appropriate for determining pyrethroid hydrolysis activity on individual insects. The measured activity of house fly esterase was 870 relative fluorescence units (RFU) min(-1) with cis-7-CP as substrate, 1117 RFU min(-1) with trans-7-CP as substrate and 1423 RFU min(-1) with cis-trans-7-CP as substrate. The fluorescent substrates for pyrethroid-cleaving esterases described in this paper have advantages over methods already given in the literature. They are substrates with structures very similar to pyrethroids, the cleavage of which can be followed by an increase in fluorescence emission at 440 nm; it takes only about 5 min to measure the reaction, and moreover the high sensitivity of the fluorescence technique allows the quantification of esterase activity on individual insects.

Animals↗
PubMed2006

Influence of Portland cement amendment on soil pH and residual soil termiticide performance.

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.

Animals↗
PubMed2001

Monitoring insecticide resistance in house flies (Diptera: Muscidae) from New York dairies.

House flies were collected from dairies across New York state and the levels of resistance to seven insecticides were measured using standard laboratory assays with three to five diagnostic concentrations. The highest levels of resistance were found for tetrachlorvinphos, permethrin and cyfluthrin. Although levels of resistance to methomyl were somewhat lower, they were among the highest ever reported for field-collected house flies. Resistance to pyrethrins was limited primarily to the lowest diagnostic concentration. House flies were susceptible to fipronil at all dairies, suggesting that this material would be highly effective for fly control. The levels of resistance were similar at all the dairies, irrespective of their insecticide use, suggesting substantial movement of flies between facilities. Relative to resistance levels found at New York dairies in 1987, resistance levels had increased for permethrin, were unchanged for tetrachlorvinphos and had decreased for dimethoate. To identify a single diagnostic concentration that could be used in the laboratory assays to assess accurately resistance levels in future studies, we carried out a 'simulated' field bioassay using formulated materials. A diagnostic concentration for each insecticide is proposed on the basis of a comparison of our bioassays.

Adaptation, Physiological↗
PubMed2004

Dissipation of three organochlorine and four pyrethroid pesticides sprayed in a greenhouse environment during hydroponic cultivation of gerbera.

A wide range of pesticides (insecticides, acaricides and fungicides) is used in the hydroponic cultivation of gerbera. The fate and behaviour of some of these commonly used pesticides (organochlorine and pyrethroid insecticides/acaricides) in a greenhouse installation was investigated. The concentrations of endosulfan, dicofol, tetradifon, permethrin, bifenthrin, cypermethrin and deltamethrin in the air of the greenhouse were related to their physicochemical properties and respective application rates. Of these compounds, endosulfan exhibited the highest concentration in the greenhouse air 2 h after application (10 microg m(-3)), due to its highest volatility; afterwards, up to 12 h post-application, a rapid decrease was recorded which finally led to a concentration of 0.41 microg m(-3) at 6 days post-application. Dicofol exhibited the same trend of dissipation in the greenhouse air; its concentration decreased from 0.27 microg m(-3) immediately after the application to 0.12 microg m(-3) at 6 days post-application. Tetradifon, bifenthrin and permethrin were found at concentrations lower than 0.1 microg m(-3) at 2 h post-application, and cypermethrin and deltamethrin could not be detected. The concentrations of all the above pesticides in the drain water of the open hydroponic system were relatively high immediately after application and decreased rapidly during the following 3 days. In the closed hydroponic system, all the pesticides accumulated in the nutrient solution during the first 24 h after application and slowly decreased in concentration over the following 3 days. The spray operators applying these pesticides were exposed to rather high concentrations and the spray deposits were monitored on the chest and forehead of the operator. Endosulfan exhibited the highest concentrations of the seven pesticides. The organochlorine pesticides (endosulfan, dicofol and tetradifon) were usually detected at higher concentrations on the chest than on the forehead of the operator; pyrethroids were detected at higher concentrations on the forehead than on the chest of the operator.

Aerosols↗
PubMed2005

Managing Eastern tent caterpillars Malacosoma americanum (F) on horse farms to reduce risk of mare reproductive loss syndrome.

An equine disease now known as mare reproductive loss syndrome (MRLS) struck the Ohio Valley in 2001-2002 causing thousands of foal abortions and enormous economic loss. Evidence that pregnant mares' exposure to Eastern tent caterpillars Malacosoma americanum (F) induces MRLS created an urgent call for control measures suitable for use on horse farms. We surveyed egg mass distribution and monitored emergence in wild cherry trees, and evaluated reduced-risk treatment strategies including foliage sprays, trunk injections, winter egg mass treatments and barrier sprays to intercept larvae entering pastures. Egg masses were concentrated in the lower canopy, on exposed sides of trees. Larval emergence began in mid-March. Emergence was prolonged (3-4 weeks) in 2002, a typically cool spring, but more synchronized in warmer 2003. Winter treatment of egg masses with bifenthrin or permethrin in a penetrating solvent prevented emergence, but 3% horticultural oil was ineffective for that purpose. Insecticidal soap or oil sprayed directly on neonates gave relatively poor control. Bifenthrin and spinosad were effective as foliage sprays against all instars, their field-weathered residues active for at least 7 days. Bacillus thuringiensis Berliner var kurstaki controlled neonates within 3 days but was less active against late instars, with shorter residual action than bifenthrin or spinosad. Larvae did not avoid insecticide-treated leaves. Trunk microinjection of cherry trees with dicrotophos was effective against all instars, whereas microinjection with milbemectin or abamectin gave poor or inconsistent control. Trunk injection with emamectin benzoate also was effective. Dry permethrin residues controlled late instars crawling in pasture grass for at least 7 days. Factors complicating M americanum management on horse farms are discussed.

Abortion, Veterinary↗
PubMed1992

Analysis of carcinogenic activity of some pesticides in a medium-term liver bioassay in the rat.

Eight pesticides were tested in a medium-term bioassay based upon the induction of preneoplastic lesions in the liver. Rats were initially given diethylnitrosamine intraperitoneally at a dose of 200 mg/kg body weight and 2 weeks later were treated with the pesticides for 6 weeks and then killed; all rats had a partial hepatectomy at week 3. Hepatocarcinogenic potential was assessed by comparing the number and area of glutathione S-transferase placental form positive foci in the liver with those of controls given diethylnitrosamine (DEN) alone. Positive results were seen with p,p-DDT and Triadimefon. Permethrin (mixture of 39% cis form and 61% trans form) showed borderline results. Permethrin (25/75), Deltamethrin, Cypermethrin (52/48), while Trimorphamide and Propineb gave negative results. Our findings provide experimental evidence to indicate that compounds active in this assay have a potential for liver carcinogenicity in rodents.

Animals↗