Effects Of Permethrin Research Articles

GPR39-mediated ERK1/2 signaling reduces permethrin-induced proliferation of estrogen receptor α-negative cells

Certain insecticides are known to have estrogenic effects by activating estrogen receptors through genomic transcription. This has led researchers to associate specific insecticide use with an increased breast cancer risk. However, it is unclear if estrogen receptor-dependent pathways are the only way in which these compounds induce carcinogenic effects. The objective of this study was to determine the impact of the pyrethroid insecticide permethrin on the growth of estrogen receptor negative breast cancer cells MDA-MB-231. Using tandem mass spectrometric techniques, the effect of permethrin on cellular protein expression was investigated, and gene ontology and pathway function enrichment analyses were performed on the deregulated proteins. Finally, molecular docking simulations of permethrin with the candidate target protein was performed and the functionality of the protein was confirmed through gene knockdown experiments. Our findings demonstrate that exposure to 10–40 μM permethrin for 48 h enhanced cell proliferation and cell cycle progression in MDA-MB-231. We observed deregulated expression in 83 upregulated proteins and 34 downregulated proteins due to permethrin exposure. These deregulated proteins are primarily linked to transmembrane signaling and chemical carcinogenesis. Molecular docking simulations revealed that the overexpressed transmembrane signaling protein, G protein-coupled receptor 39 (GPR39), has the potential to bind to permethrin. Knockdown of GPR39 partially impeded permethrin-induced cellular proliferation and altered the expression of proliferation marker protein PCNA and cell cycle-associated protein cyclin D1 via the ERK1/2 signaling pathway. These findings offer novel evidence for permethrin as an environmental breast cancer risk factor, displaying its potential to impact breast cancer cell proliferation via an estrogen receptor-independent pathway.

A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles

BackgroundHead louse infestation is an important public health problem, and expanding resistance to permethrin is a major challenge to its control. The mapping and detection of pyrethroid resistance are essential to the development of appropriate treatments and ensure the effectiveness of current measures. The aim of this study was to present the phenotypic and genotypic basis of permethrin resistance and identify knockdown resistance (kdr) mutations in head louse populations in northwestern Iran.MethodsAdult head lice were collected from 1059 infested girls in Ardebil, East Azerbaijan, West Azerbaijan and Zanjan Provinces, northwestern Iran. The toxicity of permethrin and the possible synergistic effect of piperonyl butoxide (PBO) on this toxicity were assessed using bioassays. Fragments of voltage-sensitive sodium channels (vssc) and cytochrome b (cytb) genes were amplified and analyzed for the detection of knockdown resistance (kdr) mutations and mitochondrial groups. Moreover, genotypes of the two hot spot regions of the vssc gene were determined by melting curve analysis of amplicons.ResultsA total of 1450 adult head lice were collected during 2016–2021. Live lice were exposed to a dose of 1% permethrin for 12 h, and the median lethal time (LT50) and time to achieve 90% mortality (LT90) were determined to be 6 and 14.8 h, respectively. Topical application of 2 and 16 ng permethrin per louse resulted in 25% and 42.11% mortality, respectively. Pre-exposure of samples to 3% piperonyl butoxide had no synergistic effect on the effects of permethrin. Analysis of the 774-bp vssc gene fragment showed the presence of the M815I, T917I and L920F mutations, wild-type and T917I mutation, in 91.6%, 4.2% and 4.2% of samples, respectively. Investigation of the mitochondrial cytb gene demonstrated the predominance of clade B. The frequency of domain II segment 4 (S4)-S5 kdr genotypes in mitochondrial groups was identical, and heterozygotes were present in 93.5% of samples. A significant difference was detected in the frequency of domain IIS1-S3 kdr genotypes, and the frequency of resistant alleles and heterozygotes was higher in clade B than in clade A.ConclusionsThe presence of kdr mutations in the vssc gene and the non-synergist effect of PBO indicate that pyrethroid target site insensitivity is the main resistance mechanism. This phenomenon and the high frequency of resistant alleles necessitate that new pediculosis management programs be developed. Further studies need to be conducted to identify all factors contributing this resistance and to develop alternative pediculicides.Graphical

Effect of permethrin and cypermethrin on oxygen consumption of a fresh water fish, H. fossilis

Fish provide a high caloric diet to a large number of people all over the world but indiscriminate use of these pollutants has reduce fish growth synthetic pyrethroids may decrease nutritive value, as well as, there compounds may also rich to human body through fish flesh and will cause toxicity to human being also. Two sources of oxygen are potentially available to fishes while most use only dissolved oxygen; others have the ability to obtain oxygen from the atmosphere. All breathing fishes also use dissolved oxygen to some extent, under toxic condition, the oxygen supply becomes deficient and number of poisons become more toxic increasing the amount of poison being exposed to the animal. The fish breathe more rapidly and the amplitude of respiratory movement will increase. The result of the present study suggest that the altered rates of respiration of fresh water fish may serve as a rapid biological monitor of the pesticides exposure to important components of fresh water fish community.

Stress, growth, cytokines and histopathological effects of permethrin in common carp (Cyprinus carpio)

ABSTRACT Although permethrin has low toxicity in mammals, it affects many aquatic organisms directly or indirectly due to its high insecticide potential. In this study, changes in the levels of some hormones, cytokines and histopathological effects in the gill and liver were studied in common carp (Cyprinus carpio) exposed to permethrin at different doses (0, 10 and 20 ppm) and durations (4 days and 21 days). Permethrin exposure showed significant (P < 0.05) elevation in the serum levels of adrenocorticotropic hormone (ACTH), cortisol (CORT), tumor necrosis factor-α (TNF-α), interleukin 1β (IL- 1β) and interleukin 6 (IL-6) while decrease in growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in duration- and concentration dependent-manner compared to the control group. Histopathological findings such as reduction in secondary interlamellar space in the gill tissue, shortening of secondary lamellae, merging, fusion, oedema and telangiectasia were obtained. In the liver tissue, histopathological symptoms such as vacuolization of hepatocytes, passive hyperaemia, mononuclear cell infiltration and hepatocellular degeneration were observed. As a result, it was determined that permethrin had a toxic effect on common carp depending on the dose and duration exposure.

Effect of interventions to reduce malaria incidence among military personnel on active duty: study protocol for a cluster randomised controlled trial of the impact of etofenprox-treated uniforms, permethrin-treated uniforms and DEET insect repellent

BackgroundWhile there is strong evidence that bite protection methods such as permethrin-treated clothing and topical insect repellents are protective against insect bites, there are few studies assessing the impact on malaria infection. This study will estimate the protective efficacy of treated uniforms and DEET insect repellent on the incidence of malaria infection among military personnel in an operational setting. Permethrin-treated uniforms used with DEET lotion will be compared to etofenprox-treated uniforms with DEET lotion. The effect of DEET lotion will be estimated by comparing permethrin-treated uniforms with DEET or placebo lotion.MethodA cluster randomised double-blind placebo-controlled trial is planned to evaluate the effectiveness of the interventions on preventing malaria infections in soldiers on active duty at Mgambo National Service Camp in Tanga, Tanzania. The arms are (1) permethrin-treated uniform with 30% DEET liposome formula; (2) permethrin-treated uniform with placebo lotion; (3) candidate insect repellent system, i.e. etofenprox-treated uniform with 30% DEET liposome formula; and (4) placebo, i.e. untreated uniforms with placebo lotion. The primary outcome is the incidence of Plasmodium falciparum malaria infection detected by polymerase chain reaction (PCR) by active case detection using surveys every 2 weeks for 12 months. Rapid diagnostic tests will be used for the diagnosis of participants with symptoms.The unit of randomisation will be combania: companies formed by recruits aged 18 to 25 years; combania do activities together and sleep in the same dormitory. Unequal randomisation will be used to optimise statistical power for the primary comparison between permethrin-treated uniforms with DEET and etofenprox-treated uniforms with DEET.DiscussionThis trial will provide the estimate of the effects of permethrin with DEET compared to those of the new fabric treatment etofenprox with DEET and any additional effect of using DEET. The results will inform strategies to protect military personnel and civilians who have more outdoor or occupational malaria exposure than the general public.Trial registrationClinicalTrials.govNCT02938975.

Effects of Permethrin or Deltamethrin Exposure in Adult Sprague Dawley Rats on Acoustic and Light Prepulse Inhibition of Acoustic or Tactile Startle.

The effects of permethrin (PRM) and deltamethrin (DLM) on acoustic or light prepulse inhibition of the acoustic startle response (ASR) and tactile startle response (TSR) were studied in adult male Sprague Dawley rats. Preliminary studies were conducted to optimize the parameters of light and acoustic prepulse inhibition of ASR and TSR. Once these parameters were set, a new group of rats was administered PRM (0 or 90mg/kg) or DLM (0 or 25mg/kg) by gavage in 5mL/kg corn oil. ASR and TSR were assessed using acoustic or light prepulses 6, 8, and 12h after PRM and 2, 4, and 6h after DLM exposure. PRM increased ASR 6h post-treatment with no interaction with acoustic prepulse levels and with no effect on TSR. When light was used as the prepulse, PRM increased ASR and TSR at 6h with no interaction with prepulse levels. DLM decreased ASR and TSR on trials without prepulses but not on trials with acoustic prepulses. DLM also decreased ASR when light prepulses were present 4h post-treatment. A final experiment assessed whether the house light in the test cabinet affected ASR and TSR after PRM or DLM exposure. Rats had increased ASR and TSR when house lights were on compared with when they were off, but lighting did not differentially interact with PRM or DLM. Light and acoustic prepulses of ASR and TSR have different effects depending on the test agent and the test parameters.

The efficacy and safety of permethrin 2.5% with tea tree oil gel on rosacea treatment: A double-blind, controlled clinical trial.

Rosacea is a chronicskin condition that typicallyaffects the face and it results in redness and inflammation. The main risk factors of this disease are Demodex folliculorum, living in the pilosebaceous units. To evaluatethe efficacy and safty of permethrin 2.5% in combination withtea tree oil (TTO) topical gel versusplacebo on Demodex density (Dd) and clinical manifestationusingstandard skin surface biopsy (SSSB) in rosacea patients. In this double-blind, randomized clinical trial, 47 papulopustular rosacea patients were enrolled, with 35 patients finishing the 12weeks of treatment. Each patient used permethrin 2.5% with TTO on one side of the face and a placebo on the other, twice daily for 12weeks. SSSB, photography and clinical rosacea scores according to National Rosacea Society, as well as adverse drug reaction (ADRs) were reported at the baseline, 2nd, 5th, 8th, and 12th weeks. A total of 47 patients were enrolled with papulopustular rosacea, and 35 patients finished the study. The effects of permethrin 2.5% with TTO gel on mite density were significant at week 5, 8, 12 (P value=.001). Clinical features and global assessments showed papules, pustules and nontransient erythema had improvement in drug group after 12weeks (P values <.05). The improvement of burning and stinging and dry appearance was greater than the placebo gel (P value <.05). Itching in placebo group was significantly more than other group (P value=.002). Administration of permethrin 2.5% with TTO gel demonstrated good efficacy and safety in rosacea. This topical gel inhibited the inflammatory effects of rosacea and reduced Demodex mite.

EFFECTIVENESS OF WET COMBING COMPARED WITH 1% PERMETHRIN LOTION FOR THE TREATMENT OF PEDICULOSIS CAPITIS

Objective: Pediculus humanus capitis is an ectoparasite that sucks blood from the patient’s scalp. Gamma-hexachlorocyclohexane is an effective treatment but its use has been discontinued because of its neurotoxicity. Although the replacement pediculicide is permethrin, this is not affordable for everyone, and thus the recommended treatment is wet combing. The aim of this study is to evaluate the effectiveness of permethrin compared with wet combing for eliminating pediculosis.&#x0D; Methods: This study was a randomized controlled trial (RCT) conducted in a boarding school in Bogor District; the data were collected in July–August, 2018. Subjects were regarded as infested if lice were found during examination. Infested subjects were divided into two groups. In the permethrin group, the hair was wetted with permethrin lotion and left for 10 min. Afterwards, a fine-toothed comb was used to remove lice, and then the subjects were instructed to wash their hair with shampoo. On day 14, each subject’s head was reexamined to determine the cure rate. The wet-combing group was treated similarly but using conditioner instead of permethrin.&#x0D; Results: Of 121 subjects, 88.4% were infested with head lice. The cure rate after one week of treatment was 66% in the permethrin group and 63% in the wet-combing group. After a two-week course of treatment, the cure rate increased to 94% in permethrin group and 89% in the wet-combing group. There was no significant difference in cure rate between permethrin and wet combing after a one-(P = 0.740) or two-week (P = 0.507) course of treatment.&#x0D; Conclusion: The prevalence of pediculosis capitis in a boarding school in Bogor District was 88.4%. Wet combing treatment was as effective as permethrin for treating pediculosis capitis.

Isoenzymes of Aedes albopictus (Diptera: Culicidae) Glutathione S-transferases: Isolation and expression after acute insecticide treatment

Glutathione S-transferases (GSTs) from susceptible Aedes albopictus larvae were partially isolated using two different purification strategies (GSTrap™ HP and GSH-agarose affinity columns) and the effects of permethrin and DDT on expression of the GSTs were investigated. Distinct double bands on SDS-PAGE with molecular weights between 20 and 25 kDa were successfully purified using GSTrap™ HP while a single band of 24.5 kDa was purified using GSH-agarose. The isolated GSTs belonged to the Delta, Sigma and Theta GST classes. When exposed to permethrin, one isoform of Theta, four isoforms of Sigma and thirteen isoforms of Delta GSTs showed an increased expression between 1.4-fold and 2.5-fold while DDT treatment resulted in between 1.4-fold and 3.2-fold increased expression in one isoform of Theta, four isoforms of Sigma and eleven isoforms of Delta GSTs (p < .05). This study indicated that GSTrap™ HP was more competent in isolating Ae. albopictus GSTs compared to GSH-agarose and also variable expression of GST isoforms occur in response to different insecticides. This information may be useful for improving insecticide resistance management strategies in aspect of molecular resistant and evolutionary tolerant detoxification enzyme.

Effect of permethrin (pyrethroid insecticide) on the biochemical response of the freshwater amphipod Echinogammarus tacapensis (Chevreux and Gauthier, 1924)

Pyrethroids, the widely used pesticides, are highly toxic to aquatic organisms. However, little information is available on their toxicity on crustaceans. We utilized imagoes of Echinogammarus tacapensis to elucidate the effects of sublethal concentrations of permethrin. The LC50 (48, 72, and 96 h) was assessed considering several pesticide concentrations (ranging between 0.5 and 100 ng L−1) using the Regtox package and were found to be 13.88, 8.974, and 4.259 ng L−1, respectively. The biomarkers’ response was analyzed using animals exposed to 0.35, 0.7, and 1.4 ng/L of permethrin for 4 days. The catalase activity was significantly induced after 48 h of exposure to the three permethrin concentrations. Additionally, the glutathione S-transferase activity was increased in a concentration-dependent manner. However, exposed to C1 (0.35 ng L−1), the superoxide dismutase (SOD) activity showed no significant change compared to control values. The hydrogen peroxide (H2O2) rate was found to be similar to the SOD variation. Our findings suggest that permethrin poses a potential threat to freshwater amphipods and thus, the test species can be a useful tool for pesticide toxicity biomonitoring due to their small size, easy husbandry, short life cycle, and high fecundity.

Exposure to permethrin promotes high fat diet-induced weight gain and insulin resistance in male C57BL/6J mice

Permethrin is a pyrethroid pesticide that was previously reported to promote fat accumulation and insulin resistance in vitro. A recent study in female mice also found that permethrin could promote high fat-induced insulin resistance. The effects of permethrin on glucose and lipid metabolisms in male mice, however, remain unknown. The purpose of this study was to investigate the effects and interactions of permethrin exposure (50, 500, and 5000 μg/kg body weight/day) and dietary fat (low fat, 4% w/w; high fat, 20% w/w) on development of obesity and insulin resistance in male C57BL/6J mice. Our results showed that permethrin treatment significantly increased body weight, fat mass, and insulin resistance with high fat diet, but not with low fat diet, without influencing energy intake. Permethrin treatment also significantly increased serum levels of insulin, glucose, leptin, triglycerides and cholesterol. Further results showed that permethrin inhibited AMP-activated protein kinase in white adipose tissue. These results suggest that permethrin interacts with dietary fat to alter lipid and glucose metabolisms in male C57BL/6J mice.

Management of Head Louse Infestations in the United States-A Literature Review.

Head lice are a source of scalp irritation, social disruption, and loss of school time. Health care providers need authoritative information to help avoid the costs and risks of ineffective treatment. A review was completed to provide relevant information on infestation treatments available in the United States. Three major biomedical databases were searched from 1985, when current products were first available, to 2014, focusing on U.S. A total of 579 references remained after duplicates were removed. A search of the U.S. Food and Drug Administration website and labels of approved products were reviewed. A marked decline in the effectiveness of permethrin and synergized pyrethrins was found, probably because of resistance arising from widespread and indiscriminate use, and the emergence of knockdown resistance mutations. The potential toxicity of lindane in the setting of readily available, safer, and more effective alternatives, should limit its use. Prescription products shown to be safe and effective with a single application, without nit combing, are topical ivermectin, malathion, and spinosad, whereas benzyl alcohol requires two applications. Home remedies such as mayonnaise, and essential oils, have not been demonstrated to be safe or effective, and may carry potential for severe adverse events. The high risk of failure of over-the-counter treatments in eliminating head louse infestations drives a need for health care provider recognition of the limitations of current treatments and for judicious use of treatments that remain effective.

Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing.

Pediculosis is a prevalent parasitic infestation of humans, which is increasing due, in part, to the selection of lice resistant to either the pyrethrins or pyrethroid insecticides by the knockdown resistance (kdr) mechanism. To determine the extent and magnitude of the kdr-type mutations responsible for this resistance, lice were collected from 138 collection sites in 48 U.S. states from 22 July 2013 to 11 May 2015 and analyzed by quantitative sequencing. Previously published data were used for comparisons of the changes in the frequency of the kdr-type mutations over time. Mean percent resistance allele frequency (mean % RAF) values across the three mutation loci were determined from each collection site. The overall mean % RAF (±SD) for all analyzed lice was 98.3 ± 10%. 132/138 sites (95.6%) had a mean % RAF of 100%, five sites (3.7%) had intermediate values, and only a single site had no mutations (0.0%). Forty-two states (88%) had a mean % RAF of 100%. The frequencies of kdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles. The loss of efficacy of the Nix formulation (Prestige Brand, Tarrytown, NY) from 1998 to 2013 was correlated to the increase in kdr-type mutations. These data provide a plausible reason for the decrease in the effectiveness of permethrin in the Nix formulation, which is the parallel increase of kdr-type mutations in lice over time.

Use of electroencephalography (EEG) to assess CNS changes produced by pesticides with different modes of action: Effects of permethrin, deltamethrin, fipronil, imidacloprid, carbaryl, and triadimefon

The electroencephalogram (EEG) is an apical measure, capable of detecting changes in brain neuronal activity produced by internal or external stimuli. We assessed whether pesticides with different modes of action produced different changes in the EEG of adult male Long–Evans rats. The EEG was recorded using two montages (visual cortex referenced to the cerebellum and to the frontal cortex) in unrestrained rats at the time of peak behavioral effects. Pesticides included: permethrin and deltamethrin (Type I and Type II pyrethroids; 2h), fipronil (single and repeated doses; phenylpyrazole; 6h), imidacloprid (neonicotinoid; 2h), carbaryl (carbamate; 0.5h), and triadimefon (triazole; 1h), using dosages that produced approximately an ED30 or an ED50–ED80 change in motor activity. Permethrin (43, 100mg/kg) increased amplitudes or areas (delta, alpha, or gamma bands) in the EEG. Deltamethrin (2.5, 5.5mg/kg) reduced the amplitudes or areas of the delta, theta, alpha, beta, and gamma bands, but the changes were not dose-related. A single treatment with fipronil (25, 50mg/kg, but not 5, 10mg/kg) decreased gamma band area. Additional changes in the delta, theta, and gamma bands were observed when fipronil (5, 10mg/kg) was administered for 14days. Imidacloprid (50, 100mg/kg) did not alter the EEG. Carbaryl (10, 50mg/kg) decreased theta area, and decreased delta and increased beta frequency. Triadimefon (75, 150mg/kg) produced minimal changes in the EEG. The results show that the EEG is affected differently by approximately equipotent doses of pesticides with different modes of action.

Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata

Anthracene (ANT) and permethrin (PER) are two of the more toxic compounds reaching the marine environment. This study aimed to determine the impact of these molecules on Venerupis decussata, an economically important species cultured on the Tunisian coast. Shell structure and its possible transformation upon exposure to the two contaminants were studied by X-ray diffraction and gravimetric analyses. Results revealed a phase transition in shell composition from aragonite to calcite after PER exposure, to a mixture of PER and ANT (Mix) but not for ANT alone. Catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GST) activities were determined in digestive gland and gills after exposure to ANT, PER and Mix to assess the impact of the contamination on the oxidative status of V. decussata. Enzyme activities increased in the digestive gland after PER treatment and in the gills after ANT treatment. PER exposure significantly reduced the levels of free thiols and increased levels of carbonylated proteins in the digestive gland, as compared to controls. In contrast, ANT exposure significantly reduced free thiols and increased the number of carbonylated proteins in the gills. Mix induced additive effects as measured by both enzymatic and proteomic approaches. The present study suggests that PER has a strong effect on shell structure; that PER and ANT exposure generate compound-dependent oxidative stress in the tissues of V. decussata and that a mixture of the two compounds has synergistic effects on biochemical response.

Effects of permethrin on the acoustic startle response in adult male Sprague–Dawley rats

Effects of permethrin on the acoustic startle response in adult male Sprague–Dawley rats

“Permethrin chronic exposure alters motor coordination in rats: Effect of calcium supplementation and amlodipine”

Recently was observed that pyrethroids decrease motor coordination and that calcium channels can be important targets for this effect. To contribute with this observation, this work studied the motor coordination and exploration (using hole-board apparatus), and locomotion (using open-field apparatus) of rats exposed to following treatments: permethrin (PM), PM plus calcium gluconate (CG) and PM plus amlodipine (AML). The results obtained show that CG or AML alone not changed the motor coordination while PM decreases it. CG kept the effect of permethrin; AML, however, decreased the values of permethrin to the control. Locomotor activity and exploration, which could confound results of motor coordination, were not modified by treatments. The concentration of PM in brain tissue was increased by the CG and AML. The neurosomatic index (weight brain/body weight) was increased by the PM and PM+CG. In conclusion, the combined results here obtained indicates that the calcium ion and the channels in which it is involved can be important targets for the toxic effect of pyrethroid insecticide permethrin on motor nerve activity of rats.

Sensitivity to permethrin in a Dermacentor reticulatus population from eastern Poland in laboratory study

BackgroundThe action of chemical compounds on the Palaearctic tick D. reticulatus (Fabricius) (Acari: Amblyomminae) has been poorly investigated so far. Therefore, the effects of application of permethrin on engorged D. reticulatus females have been assessed, and the survival rate for the different developmental stages of the tick species in its non-parasitic phase of the life cycle was determined upon application of the pyrethroid.MethodsEach engorged D. reticulatus female, egg batch, unfed larvae (50 specimens), or unfed nymphs (10 specimens) were sprayed with 20 μl of 0.015625%- 0.250% solutions of a Coopex WP preparation, which corresponded to 0.78125- 12.5 μg of permethrin, respectively. The effect of permethrin in the preoviposition and oviposition periods was assessed based on the length of the egg development period, number of females capable of laying eggs, number and weight of eggs laid by the females, and indicators of female reproductive rate. Delayed effects of the action of the various permethrin doses were determined by quantitative and qualitative analysis of the course of embryonic development and larval hatch. The effect of permethrin on survival of the different tick stages was assessed at a temperature of 25°C and 90% RH 48 hours after application of permethrin to one to three day-old D. reticulatus eggs, seven to ten-day-old unfed larvae and nymphs.ResultsThe investigations demonstrated that at the doses applied permethrin decreased the reproductive rate of females, but only at the dose of 6.25 μg/1 specimen was the mean number of laid eggs drastically reduced, which may result in a decrease in tick abundance already in the first generation. The embryonic development of the eggs laid by the females treated with 6.25 and 12.5 μg of permethrin/1 specimen was highly disturbed. Irrespective of the permethrin dose applied, all eggs died within 48 hours after application. 100% of unfed D. reticulatus larvae and nymphs died within 48 hours after application of permethrin doses of 6.25 μg/50 specimens and 12.5 μg/10 specimens, respectively.ConclusionsPermethrin can be recommended for D. reticulatus control, particularly in the case of tick resistance to other chemical substances.

Effects of the synthetic pyrethroid insecticide, permethrin, on two estuarine fish species

Limited toxicity data are available for estuarine and marine species and the widely used pyrethroid insecticide, permethrin. This study determined acute effects of permethrin on survival, lipid peroxidation, acetylcholinesterase activity, and splenocyte proliferation for two fish species found in South Carolina estuaries; juvenile red drum (Sciaenops ocellatus) and adult mummichog (Fundulus heteroclitus). Juvenile S. ocellatus were significantly more sensitive than adult F. heteroclitus to permethrin exposure, with a 96-h LC50 value of 8 μg/L determined for red drum compared to 23 μg/L for mummichog. Lipid peroxidation activity of the liver increased in permethrin-treated fish compared to control animals after 24 h and decreased after 96 h. Permethrin had no effect on acetylcholinesterase activity of the brain at the concentrations tested. Permethrin exposure significantly inhibited splenocyte proliferation, indicating an immunosuppressive effect. Most of the effects of permethrin on fish cellular stress enzymes and survival occurred at concentrations much higher than those typically measured in the environment. However, inhibition of splenocyte proliferation in juvenile red drum occurred at approximately twice that of measured permethrin concentrations in surface water. These findings may prove useful to the future management and regulation of pyrethroid insecticide use near estuarine habitats.

Permethrin modulates cholinergic mini-synaptic currents by partially blocking the calcium channel

Pyrethroid insecticide modulation of the voltage-gated sodium channel (VGSC) is proposed to underlie their effects on neuronal excitability by inhibiting channel inactivation and increasing channel open time. However, some in vitro evidences indicate that target sites other than VGSCs could contribute to pyrethroid disruption of neuronal activity. Cholinergic excitability in Drosophila, as in other insects and mammals, is important for activity in the central nervous system. The effects of permethrin, a putative calcium antagonist, on calcium current and cholinergic mini-synaptic transmission were investigated in the Drosophila brain. At concentration of 2.5μM, permethrin significantly decreased the calcium current and cholinergic mini-synaptic current. However, the permethrin could not antagonize the calcium current completely. Removal of calcium from the external solution produced a significant decrease of cholinergic mini-synaptic transmission. The results are consistent with the hypothesis that permethrin may modulate cholinergic mini-synaptic currents by partially blocking the calcium channel.