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Background: One bioassay for detecting acaricide resistance in livestock ticks is the adult immersion test (AIT), wherein engorged ticks are briefly immersed into a solution of a particular acaricidal compound and examined for mortality, their egg-laying capacity and offspring hatchability in vitro. Usually, the recommended label dose or an established discriminating dose of an acaricide is used to determine high mortality (≥ 95%) of susceptible tick strains. Such a test intends to detect the presence of resistance in a tick population. However, the adult immersion test does not directly translate the bioassay results to the predicted efficacy in the field. In this paper, we used the AIT as an initial screening bioassay supplemented with the resistance intensity test (RIT), a novel larval-based bioassay, wherein the resistance level can be determined and translated to the expected field efficacy. This was done by adopting World Health Organisation (WHO) guidelines for resistance detection in mosquitoes, which combines a 1 × recommended dose with 5 × and 10 × concentrated doses to reveal low, moderate and high resistance intensity, respectively. Methods: Engorged Rhipicephalus microplus ticks were collected from cattle at six different ranches across Rio Grande do Sul, Brazil, as part of the state's acaricide resistance surveillance program. Groups of adult ticks from each field collection were subjected to the AIT from each field sample. Additionally, engorged female ticks from each ranch were allowed to lay eggs, and their larval progeny aged 14 to 28 days were then used in the RIT. Deltamethrin and a combination of cypermethrin, chlorpyrifos and piperonyl butoxide were used in both tests, and the results were statistically analysed. Results: The in vitro efficacy of deltamethrin against adult ticks in the AIT ranged between 8.74% and 25.38%. The corresponding RIT results on their larval progeny indicated a high resistance level. In the immersion test, the in vitro efficacy of the combination of cypermethrin, chlorpyrifos, and piperonyl butoxide against adult ticks ranged between 49.31% and 100%. The corresponding RIT results on their larval progeny indicated a similar response ranging from fully susceptible to low or moderate resistance. The Pearson correlation coefficient (r = 0.883) showed a high correlation between tick mortality at the 1 × recommended concentrations of acaricides in both tests. Conclusions: The resistance intensity test is a valuable addition to the range of bioassays currently available for detecting acaricide resistance by determining the level of acaricide resistance. This is relevant to whether or not to continue using a particular acaricidal class for controlling cattle ticks. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the occurrence and environmental partition of urban pesticides and the dependence of these compounds on the physicochemical properties of the sediment and water of the Ceará River (fluvial and mangrove regions) located on the tropical coast of northeast Brazil. Surface sediment and water were collected from each site. Dissolved oxygen, pH, temperature, conductivity, depth, turbidity, and salinity were measured in situ. Bifenthrin, deltamethrin, permethrin, imiprothrin, and malathion were analysed in both environmental matrices. An ecological risk assessment was performed using the risk quotient (RQ) calculated from responses of aquatic organisms to the target compounds compiled in the United States Environmental Protection Agency ECOTOXicology knowledgebase (ECOTOX). The highest concentrations were found for the urban pesticides cypermethrin, permethrin, and deltamethrin, ranging from 37.39 to 367.60, 44.49 to 226.45 ng L−1, and 60.99 to 170.56 ng L−1 in water and 270.99 to 623.99, 27.00 to 307.00 ng g−1 and 0.27 to 443.48 ng g−1, in sediment in dry weight, respectively. Malathion, cypermethrin, cyfluthrin, and deltamethrin are related to chemical control performed for combatting vectors of diseases. The main sources of permethrin and imiprothrin are household insecticides. Bifenthrin may be related to its use by specialised pest control services. The study of toxic effects and the ecological risk assessment revealed cyfluthrin to be extremely toxic to marine and estuarine organisms, followed by deltamethrin, bifenthrin, cypermethrin, and permethrin, whereas imiprothrin and malathion were classified as toxic and non-toxic, respectively. The urban pesticides investigated in this study were on the same level of magnitude as those found in agricultural areas, except for malathion and imiprothrin, the levels of which were higher due to the fact that these compounds are commonly used in urban pest control. [ABSTRACT FROM AUTHOR]

Amblyomma sculptum is a relevant tick species from a One Health perspective, playing an important role as a vector of Rickettsia rickettsii, the main agent of spotted fever rickettsiosis in Brazil. In this study, we evaluated the susceptibility of two A. sculptum populations from Goiás state (midwestern Brazil) to different acaricides. The first tick population (GYN strain) originated from an experimental farm, where the ticks are annually exposed to acaricides. The second (PNE strain) was collected in a national park (Emas National Park), where the ticks had not been exposed to acaricides. Immersion tests were conducted with 21-day-old laboratory-reared larvae and nymphs originating from adult ticks collected in the areas mentioned above. The chosen acaricides were two synthetic pyrethroids (cypermethrin and deltamethrin), one organophosphate (chlorfenvinphos), one formamidine (amitraz), and two combinations of pyrethroids and organophosphates (cypermethrin, chlorpyrifos and citronellal; cypermethrin, fenthion and chlorpyrifos). Mortality data were used to determine the lethal concentration (LC) values at which 50%, 90%, and 99% of the ticks died (LC50, LC90, and LC99, respectively), and resistance ratios (RR) were calculated based on the LC values. The RR revealed differences between the acaricide-exposed (GYN) and unexposed (PNE) tick strains. The PNE strain larvae and nymphs were susceptible to all the tested acaricides. The GYN strain larvae were tolerant to cypermethrin, whereas the nymphs were tolerant to deltamethrin, chlorfenvinphos, and the combination of cypermethrin, chlorpyrifos, and citronellal (2 < RR ≤ 10). The GYN strain nymphs were resistant to amitraz (RR > 10). This is the first report of A. sculptum nymphs with resistance to amitraz and tolerance to deltamethrin, chlorfenvinphos, and the combination of cypermethrin, chlorpyrifos, and citronellal. [ABSTRACT FROM AUTHOR]

The current work evaluated the efficacy of 10 commercial acaricides in different pHs (4.5, 5.5, and 6.5) in laboratory (adult immersion tests (AIT), pH evaluation over time) and field assays (tick counts and efficacy). In the AIT (n=70), higher efficacies were obtained when the acaricide emulsion had a more acidic pH (4.5), mainly for two combinations of pyrethroids + organophosphate (acaricide 3 and acaricide 9). For amidine, a higher pH (6.5) showed a higher efficacy. Over time, there was a trend in the pH of these emulsions increasing. When the efficacy of chlorpyrifos + cypermethrin + piperonyl butoxide (acaricide 3) at different pHs was evaluated over time (0, 6, 12, and 24h) by AIT, the less acidic pH (6.5) showed a strongly variation in the acaricide efficacy range. The mean pH of the water samples from different regions of Brazil was 6.5. In the field, the association of pyrethroid + organophosphates (acaricide 9) with pH of 4.5 and 5.5 were more effective in tick control than the emulsion prepared with this same spray formulation at pH 6.5. The pH of the acaricide emulsions is an important point of attention and is recommended that the veterinary industry start to develop/share information regarding how the pH can affect the acaricide efficacy. [ABSTRACT FROM AUTHOR]

Simple Summary: Ticks represent a major health and economical issue for cattle farmers since bovine are infested by the cattle tick Rhipicephalus microplui; This tick is responsible for direct economic loss and can be the vector of several diseases. Many acaricidal drugs are routinely used to control tick infestation, but tick populations are becoming resistant to different drugs. Our work evaluated for the first time the resistance of a tick population from the Lower Amazon region to three different and commonly used acaricidal drugs. We found that the tested tick population had a marked resistance to Cypermethrin and Deltamethrin and mild resistance to Amitraz. Farmers in the region should avoid the use of such acaricides to control ticks, especially Cypermethrin and Deltamethrin. There is limited information on the resistance to acaricidal drugs of the cattle tick Rhipicephalus microplus in the Lower Amazon region. Thus, we aimed to determine the efficiency of three widely used acaricide products (Amitraz, Cypermethrin, and Deltamethrin) in the control of this tick species. The adult immersion test was used on engorged female ticks sampled on farms in the Lower Amazon region, Brazil. For the test, homogeneous batches of 10 engorged females were placed in Petri dishes and immersed in the tested acaricidal drugs, using four replicates of each acaricide and three replicates as a negative control, immersed in distilled water. The acaricides were diluted as recommended by the manufacturers, and the ticks were submerged for five minutes. Mortality of engorged females, production of eggs, and percentage of larval hatching were evaluated. Tick mortality was 2.5%, 7.5%, and 0% for Amitraz, Cypermethrin, and Deltamethrin, respectively. The percentage of larval hatching was 53.7% for Amitraz, 88.7% for Cypermethrin, and 80.0% for Deltamethrin. As recommended by the FAO, for the acaricide to be considered effective, it must have a control rate ≥95%. Among the tested acaricides, Amitraz showed an efficacy of 90.5%, Cypermethrin 10.4%, and Deltamethrin 26.6%. Ticks from the lower Amazon showed marked resistance to Cypermethrin and Deltamethrin and mild resistance to Amitraz. This is the first report of acaricidal resistance in the region. [ABSTRACT FROM AUTHOR]

Rhipicephalus microplus is among the most important ectoparasites for livestock. The use of synthetic acaricides has raised some concerns due to the selection of tick populations that are resistant to acaricides and environmental contamination. Therefore, plant extracts have been used as alternatives for the treatment of animals infested with ticks. In this study, R. microplus populations from seven different dairy farms were collected and assessed for their resistance to the acaricides cypermethrin or trichlorfon. Larvae of the most resistant population were used in assays to evaluate the acaricide effect of leaf extracts from plants of the Brazilian savanna. The most active extracts were also tested against fully engorged females. Among seven tick populations, five and three showed resistance level ≥ III for cypermethrin or trichlorfon, respectively. The most resistant tick population was evaluated in mortality assays with the plants Piptadenia viridiflora, Annona crassiflora, Caryocar brasiliense, Ximenia americana, and Schinopsis brasilienses. The ethanolic extracts of C. brasiliense, X. americana and S. brasilienses showed higher larvicidal effects in comparison to the other extracts and cypermethrin. The ethanolic extract of X. americana showed 60.79 % efficacy against fully engorged females of the acaricide resistant tick strain. The ethanolic extracts of C. brasiliense, X. americana, and S. brasilienses showed peaks in HPLC-DAD, indicating the presence of tannins and flavonoids. Three of the plants showed promising results and should be explored in further studies to develop novel tools to control R. microplus in cattle., Competing Interests: Declaration of Competing Interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The aim of the present study was to evaluate acaricide resistance in Rhipicephalus microplus on a ranch in Brazil. Adult immersion tests were performed using commercial formulations containing organophosphorus compounds (OPs), amidines, synthetic pyrethroids (SPs), OP+SP combinations, and fluazuron. The larval immersion test was used to evaluate susceptibility to ivermectin and fipronil. Resistance was detected to all chemical classes with efficacies of 3.2% (Amitraz 12.5 g), 34.2% (Dichlorvos 45 g + Cypermethrin 5 g), 14.6% (Chlorpyrifos 5 g + Cypermethrin 2 g), 72.9% (Deltamethrin 2.5 g), 60.3% (Cypermethrin 15 g), 70.2% and 51.5% (Cypermethrin 15 g + Chlorpyrifos 25 g + Citronella 1 g), 20.5% (Dichlorvos 60 g + Chlorpyrifos 20 g), 0% (Cypermethrin 15 g), 46.2% (Ethion 2 g + Chlorpyrifos 10.6 g + Cypermethrin 6.2 g). Only two associations, one containing two OPs + one SP and another with a high concentration of OP + SP exhibited efficacy of 100% and 96.3%, respectively. Resistance to fluazuron, ivermectin (Resistance ratio [RR] = 3.08), and fipronil (RR = 3.18) was also detected. The present results indicate resistance to all classes of an existing contact or systemic acaricides and combinations of pyrethroids and organophosphates in an isolate of R. microplus. [ABSTRACT FROM AUTHOR]

Anastrepha fraterculus (Wiedemann, 1830) is the main pest of fruit in southern Brazil. The use of toxic baits is one of the alternatives for its management. In this study, the toxic baits Anamed + malathion (10,000 mg/liter), Flyral 1.25% + malathion (2,000 mg/liter), and Gelsura (alpha-cypermethrin, 2,000 and 4,000 mg/liter) were highly toxic to the adults of A. fraterculus (lethal time [LT50] < 7 h). In contrast, Success 0.02 CB had an LT50 of 48.4 h. In the absence of rain, all the formulations had residual effects (>90% mortality) on A. fraterculus adults up to 21 d after treatment (DAT). In the presence of 5, 25, and 50 mm of rainfall, there was a significant reduction in the residual effect over time. However, with up to 50 mm of rain, Anamed + malathion and Gelsura 2,000 and 4,000 mg/liter caused between 43.0 and 79.0% of mortality. In the field, during two consecutive seasons (2015/2016 and 2016/2017), applications of Gelsura 2,000 mg/liter (four applications/season) caused population suppression of the pest throughout the apple fruiting period. However, in the 2016/2017 season, in the area using Gelsura, a higher percentage (≈12%) of apple fruits damaged by A. fraterculus females was observed when compared with the area with insecticide application (damage <3%). The toxic bait Gelsura (2,000 and 4.000 mg/liter) was shown to be promising for use in the management of A. fraterculus , with results similar to those with the application of synthetic insecticides. [ABSTRACT FROM AUTHOR]

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Brazilian spotted fever (BSF) is an endemic anthropozoonosis caused by Gram-negative bacteria ( Rickettsia rickettsii ) that is associated with the risk of human infection by ticks. In the city of Americana, São Paulo (SP), Brazil, there were 12 cases (67% lethal) between 2004 and 2015. This study evaluated the effectiveness of control over tick infestations in an area at risk of BSF, in a field trial on an association of alpha-cypermethrin (3%) and flufenoxuron (3%) (Tenopa ® ) conducted in Americana. The infestation levels of the target species ( Amblyomma sculptum and Amblyomma dubitatum ) in the field trial were evaluated through acarological surveys (CO 2 traps) on days 0, 22, 43 and 62 after treatment, both in the treatment area and in a control area. In the treatment area, the insecticide formulation was applied using a motorized sprayer, at the dosage of 80 mL/10 L of water per 200 m 2 . These surveys in the treatment area showed that there were reductions in the infestation levels of the adult stage on days 22 (33%), 43 (87%) and 62 (70%) and immature stages (nymphs and larvae) on days 22 (54%), 43 (87%) and 62 (97%), in relation to day zero and to infestation levels in the control area. This study demonstrated that the product applied was effective for reducing the environmental infestation of ticks and that this effect persisted two months after a single application in areas of proven risk of BSF. [ABSTRACT FROM AUTHOR]

Brazil is one of the largest consumers of pesticides in the world. This high consumption has resulted in higher potential health risk to agricultural farm workers due to occupational exposure. Hence, the aim of this study is to evaluate genomic instability, using Buccal Micronucleus Cytome (BMCyt) and telomere length (TL) measurement as biomarkers of occupational exposure to pesticides in rural workers living in the State of São Paulo, Brazil. Genomic instability was evaluated in 81 pesticide-exposed farm workers (69 males and 12 females) with a mean age of 49.16 ± 10.06 years and a mean time job of 30.00 ± 14.00 years,81 non-exposed individuals (62 males and 15 females) with a mean age of 47.87 ± 10.66 years. BMCyt results showed significantly higher levels of cell damage (micronuclei and binucleated cells) and cell death (karyorrhectic and condensed chromatin cells) in subjects exposed to pesticide when compared to those non-exposed (p < 0.05). Although our results did not show significant differences in TL among exposed and non-exposed groups, effects in TL due to pesticide exposure was found in a multivariable linear regression model when we stratified the groups by age (≤ 49 years and ≥ 50 years old; β = 11.21, p = 0.006). In addition, TL reduction on was identified in relation to an increase in cigarette pack consumption (β = −0.633, p = 0.045). Furthermore, exposure to specific pesticides presented different effects in TL. Cypermethrin exposure resulted in a reduction in TL (β = −18.039, p = 0.018), while abamectin exposure led to an increase in TL (β = 23.990, p = 0.007). Thus, our findings substantiate genomic instability due to pesticides exposure. [Display omitted] • Pesticides exposure induced DNA damage and cell death. • Pesticides exposure has an important role in TL maintenance, could leads a reduction or increase on TL. • The BMCyt assay and a TL are promising biomarkers to pesticides exposure. [ABSTRACT FROM AUTHOR]

Abstract: The cattle tick Rhipicephalus (Boophilus) microplus causes expressive damage to livestock in Brazil and other countries. Its control is becoming more difficult due to the development of resistance in populations. Early detection of resistance can help in developing effective control strategies. This study evaluated the susceptibility of R. microplus to cypermethrin and chlorpyriphos and was the first attempt to identify the mechanism of resistance (target site insensitivity) in cattle tick populations from Minas Gerais state (Southeastern Brazil). Engorged female ticks were collected from 10 ranches within the state of Minas Gerais, and susceptibility was evaluated with the larval packet test (LPT) using technical grade cypermethrin and chlorpyriphos. It was possible to analyze LPT results of seven populations. Target site insensitivity was investigated in all 10 isolates by using molecular approaches for detection of the T2134A substitution within the domain III S6 segment and the C190A in the domain II S4-5 linker from the para-type sodium channel gene. LPT showed that all seven populations were resistant to cypermethrin with resistance ratio (RR) ranging from 16.0 to 25.0 and 85.7% were resistant to chlorpyriphos (RR=2.2–15.6). Although the T2134A mutation was not detected, the C190A mutation was highly prevalent, being present in 82–100% of the alleles sampled in field populations. A significant correlation was found between the LC50 values for cypermethrin and the frequency of the C190A mutation suggesting that it might be responsible for the phenotypic resistance detected. [Copyright &y& Elsevier]

The article presents a study which determines the nature of nonextractable bound 14C-residues of cypermethrin in Brazilian soils. The study used high temperature distillation (HTD), supercritical fluid extraction (SFE), and thin-layer chromatography (TLC). Results showed that 50% of the parent compound in red yellow latosol (RYL) soil decomposed to Cl2CA.

The aims of this research were 1) to find out the possible microbiological contamination and residues of pesticides (chlorpyrifos and cypermethrin) in lettuce grown in Bahía Blanca's horticultural belt, and bacteriological quality of waters used for irrigation and post-harvest washing, 2) to investigate and compare the internalization capacity of a strain of Escherichia coli isolated from irrigation water with another hospital uropathogenic strain. Some strains of bacteria can internalize into the plant tissue. This capability presents food safety threats as they cannot be removed with standard sanitation practices. To determine bacteriological quality of lettuce, E. coli , Salmonella spp and E. coli O157: H7/NM (n = 10) were investigated. Bacteriological quality of water was determined by quantification of fecal coliforms/100 mL (n = 20). Pesticides were determined by using an improved and validated QuEChERS method combined with GC-MSD. Irrigation water in 19/20 samples did not present health risk. Bacteriological quality of lettuce met demands in 9/10 samples. Pesticides were detected in half of the samples, values exceeding the FAO recommendations. An effort is strongly recommended to implement both, best phytosanitary practices and monitoring programmes. Uropathogenic strain was able to internalize into plant tissue, while the nonpathogenic one was not.

The presence of pyrethroid compounds in hepatic tissue of Guiana dolphins (Sotalia guianensis) is reported for the first time. Twelve pyrethroids were determined in 50 animals from eight locations of the Brazilian coast. The highest average concentration of total pyrethroids (∑PYR) was 1166 ng.g -1 lw, with values ranging from 148 to 5918 ng.g -1 lw, in Ilha Grande Bay, Rio de Janeiro State, while the Espírito Santo State had the highest median, 568 ng.g -1 lw. Permethrin was the predominant compound in most areas, contributing for 42% to 81% of the ∑PYR, whereas cypermethrin was the most abundant compound in Guanabara and Sepetiba bays (79% and 81%, respectively), both located in Rio de Janeiro State. Biological factors were not correlated with pyrethroids concentration. Tetramethrin and es/fenvalerate compounds were negatively correlated to the age, suggesting degradation/metabolization capacity in these animals that increases throughout life. Despite being metabolized and excreted, the wide use of these pollutants is reflected in relevant concentrations found in Guiana dolphins. This is the first study evaluating pyrethroids in a representative number of hepatic samples and covering >2600 km of coast. The overall lack of information on pyrethroids in cetaceans highlights the importance of understanding the profile and distribution of these pollutants in dolphins which exclusively inhabit the Southwestern Atlantic coast., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Resistance to chemical insecticides detected in Aedes aegypti (L.) mosquitoes has been a problem for the National Dengue Control Program (PNCD) over the last years. In order to provide deeper knowledge of resistance to xenobiotics, our study evaluated the susceptibility profile of temephos, diflubenzuron, and cypermethrin insecticides in natural mosquito populations from the Pernambuco State, associating these results with the local historical use of such compounds. Furthermore, mechanisms that may be associated with this particular type of resistance were characterized. Bioassays with multiple temephos and diflubenzuron concentrations were performed to detect and quantify resistance. For cypermethrin, diagnostic dose assays were performed. Biochemical tests were carried out to quantify the activity of detoxification enzymes. In addition, a screening of mutations present in the voltage-gated sodium channel gene (NaV) was performed in samples previously submitted to bioassays with cypermethrin. The populations under study were resistant to temephos and showed a positive correlation between insecticide consumption and the resistance ratio (RR) to the compound. For diflubenzuron, the biological activity ratio (BAR) ranged from 1.3 to 4.7 times, when compared to the susceptible strain. All populations showed resistance to cypermethrin. Altered enzymatic profiles of alpha, p -nitrophenyl acetate (PNPA) esterases and glutathione-S-transferases were recorded in most of these samples. Molecular analysis demonstrated that Arcoverde was the only population that presented the mutated form 1016Ile/Ile. These findings show that the situation is critical vis-à-vis the effectiveness of mosquito control using chemical insecticides, since resistance to temephos and cypermethrin is widespread in Ae. aegypti from Pernambuco. [ABSTRACT FROM AUTHOR]