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Parasites & Vectors Oct 2018Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other...
BACKGROUND
Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other organophosphates were previously used. In 2014, reduced sensitivity to azamethiphos was detected in the Los Lagos Region using bioassays. The main target of organophosphates is the enzyme acetylcholinesterase (AChE). Mutations in the AChE gene are the main cause of organophosphate resistance in arthropods, including other sea lice. In the present study, we aimed to characterize C. rogercresseyi AChE(s) gene(s) and to study the association between AChE variants and azamethiphos resistance in this sea louse species.
METHODS
Samples of adult male and female C. rogercresseyi were collected in the Los Lagos Region in 2014. Twenty-four hour exposure bioassays with azamethiphos were performed to select sensitive and resistant lice. The full-length cDNA coding sequences encoding for two AChEs in C. rogercresseyi were molecularly characterized. One of the AChE genes was screened by direct sequencing in the azamethiphos-selected lice to search for variants. An additional louse sampling was performed before and after an azamethiphos treatment in the field in 2017 to validate the findings.
RESULTS
The molecular analysis revealed two putative AChEs in C. rogercresseyi. In silico analysis and 3D modelling of the protein sequences identified both of them as invertebrate AChE type 1; they were named C. rogercresseyi AChE1a and 1b. AChE1a had the characteristics of the main synaptic AChE, while AChE1b lacked some of the important amino acids of a typical AChE. A missense change found in the main synaptic AChE (1a), F318F/V (F290 in Torpedo californica), was associated with survival of C. rogercresseyi at high azamethiphos concentrations (bioassays and field treatment). The amino acid change was located in the acyl pocket of the active-site gorge of the protein.
CONCLUSIONS
The present study demonstrates the presence of two types of AChE1 genes in C. rogercresseyi. Although enzymatic assays are needed, AChE1a is most probably the main synaptic AChE. The function of AChE1b is unknown, but evidence points to a scavenger role. The AChE1a F/V318 variant is most probably involved in organophosphate resistance, and can be a good marker for resistance monitoring.
Topics: Acetylcholinesterase; Amino Acid Sequence; Animals; Antiparasitic Agents; Biomarkers; Chile; Copepoda; Drug Resistance; Female; Fish Diseases; Male; Organothiophosphates; Phylogeny; Polymorphism, Genetic; Salmon; Sequence Alignment
PubMed: 30376873
DOI: 10.1186/s13071-018-3151-7 -
Tropical Medicine & International... Dec 2020To investigate what toxicological interactions occur when binary combinations of azamethiphos and botanical monoterpenes (eugenol, menthol or menthyl acetate) are...
OBJECTIVE
To investigate what toxicological interactions occur when binary combinations of azamethiphos and botanical monoterpenes (eugenol, menthol or menthyl acetate) are applied to Triatoma infestans.
METHODS
The toxicity of binary mixtures of azamethiphos and sublethal doses of a monoterpene (eugenol, menthol or menthyl acetate) was evaluated in nymphs of the first stage of T. infestans. Experiments using exposure to filter papers and topical application were carried out. Values of Lethal Concentration 50% (LC50) were calculated in the first case, and values of Lethal Dose 50% (LD50) in the second.
RESULTS
The LC50 of azamethiphos applied on filter paper was 50.3 µg/cm . However, when it was simultaneously applied with a sublethal concentration of monoterpene, its toxicity increased (LC50 with eugenol = 11.20 µg/cm , LC50 with menthyl acetate = 5.30 µg/cm , LC50 with menthol = 7.26 µg/cm ). When applied topically, the LD50 of azamethiphos was 7.85 µg/insect, but its toxicity drastically increased when it was applied together with sublethal doses of menthol (LD50 = 0.00016 µg/insect) or menthyl acetate (LD50 = 0.00051 µg/insect). The simultaneous application with eugenol did not significantly change azamethiphos toxicity (LD50 = 12.79 µg/insect).
CONCLUSIONS
The toxicity of azamethiphos in T. infestans was synergised when it was applied together with eugenol, menthol or menthyl acetate on a filter paper. However, only menthol and menthyl acetate synergysed azamethiphos when mixtures were topically applied. The drastic effects of menthol and menthyl acetate in topical application experiments should be further studied as they could be the basis for developing more efficient triatomicidal products with a lower content of conventional insecticides than those currently used for controlling T. infestans.
Topics: Animals; Chagas Disease; Insect Control; Insect Repellents; Insect Vectors; Lethal Dose 50; Monoterpenes; Nymph; Organothiophosphates; Plant Oils; Triatoma
PubMed: 32945539
DOI: 10.1111/tmi.13488 -
Aquatic Toxicology (Amsterdam,... Nov 2021Swimming behaviour was investigated in adult egg-carrying northern shrimp (Pandalus borealis) exposed to dilute concentrations of the pesticides Alpha Max® (active...
Effects of simulated environmental discharges of the salmon lice pesticides deltamethrin and azamethiphos on the swimming behaviour and survival of adult Northern shrimp (Pandalus borealis).
Swimming behaviour was investigated in adult egg-carrying northern shrimp (Pandalus borealis) exposed to dilute concentrations of the pesticides Alpha Max® (active ingredient deltamethrin) and Salmosan® (active ingredient azamethiphos) used to control parasitic copepods in salmon aquaculture. These treatments are applied topically within fish nets or well boats. Following a short treatment period, the pesticides are directly discharged to sea, exposing non-target organisms such as P. borealis to diluted concentrations of these chemicals. Locomotor activity was measured continuously in individual shrimp over several days within which they were exposed to treatments of diluted AlphaMax® or Salmosan®. Dilutions were based on modelling and dispersion studies from the literature and were considered environmentally realistic for greater than 1 km from point of discharge. 24 h continuous flow treatments were delivered within a 3.5-day monitoring period to observe the timeline of events following the release of treatment water, addressing questions of temporal responses in locomotor activity, recognising key time points of significant events and assessing the survival capacity of the shrimp. Exposure of shrimp to 1 ng l deltamethrin triggered an immediate increase in swimming activity which reduced in intensity over the following 22 h leaving all shrimp either moribund or dead. A further exposure trial exposing shrimp to 0.2 ng l deltamethrin (nominal) showed an increase in activity at the start of exposure that continued throughout the 24 h delivery, returning to previous levels by the end of the 3.5-day monitoring period. All these shrimps survived for at least four weeks after exposure, putting the threshold concentration of deltamethrin leading to immobility or death in adult P. borealis within this study at greater than 0.2 ng l (nominal) and less than 1 ng l (measured). Exposure of P. borealis to azamethiphos at 30 ng l induced several periods of significantly increased activity within the first 10 h of exposure and an extended period of reduced activity during post exposure, though no morbidity was observed with this treatment. No significant increase in activity or morbidity was observed in shrimp during a water vehicle control assessment. Shrimps exposed to a combination of 30 ng l azamethiphos and 1 ng l deltamethrin broadly followed the response pattern shown by shrimp exposed to 1 ng l deltamethrin alone. Pesticide residues were not detected in post exposure tissue analyses for either chemical. The potential ecological significance of increased swimming activity at the start of pesticide exposures is discussed.
Topics: Animals; Copepoda; Nitriles; Organothiophosphates; Pandalidae; Pesticides; Pyrethrins; Salmon; Swimming; Water Pollutants, Chemical
PubMed: 34555744
DOI: 10.1016/j.aquatox.2021.105966 -
Sensors (Basel, Switzerland) Mar 2022Azamethiphos (AZA) is an insecticide and neurotoxic agent that causes the inhibition of acetylcholinesterase (AChE). AChE is a vital enzyme for neurotransmission because...
Azamethiphos (AZA) is an insecticide and neurotoxic agent that causes the inhibition of acetylcholinesterase (AChE). AChE is a vital enzyme for neurotransmission because it metabolizes acetylcholine neurotransmitter at the synaptic cleft and terminates synaptic transmission. It is worth mentioning that organophosphates and carbamates inhibit AChE. These AChE inhibitors bind to the active site of the enzyme and inactivate it, leading to paralysis and death. Herein, for the first time, we develop a sensitive, low-cost, and rapid electrogenerated chemiluminescence (ECL) system for the detection of AZA. The designed ECL sensor was applied for the highly sensitive detection of AZA with a wide dynamic range (from 0.1 μM to 1000 μM) and low detection limit of 0.07 μM (S/N = 3). The practical utility of the sensor demonstrates high recoveries (96-102%) in real samples of lake water and wastewater.
Topics: 2,2'-Dipyridyl; Acetylcholinesterase; Insecticides; Luminescence; Luminescent Measurements; Organothiophosphates; Ruthenium
PubMed: 35408132
DOI: 10.3390/s22072519 -
Environmental Pollution (Barking, Essex... Sep 2020Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target...
Anti-sea lice pesticides, used in the salmonid aquaculture industry, are a growing environmental concern due to their potential to adversely affect non-target crustaceans. Azamethiphos and deltamethrin are two bath treatment pesticides used on salmon farms in Norway, however, limited information is available on their impact on European lobster (Homarus gammarus) larvae in the Norwegian marine environment. Here, we firstly report the lethal (LC) and effective (EC) concentrations of azamethiphos and deltamethrin for stage I and stage II larvae, following 1-h exposures. Using a hydrodynamic model, we also modelled the dispersal of both compounds into the marine environment around selected Norwegian farms and mapped the potential impact zones (areas that experience LC and EC concentrations) around each farm. Our data shows that azamethiphos and deltamethrin are acutely toxic to both larval stages, with LC and EC values below the recommended treatment concentrations. We also show that the azamethiphos impact zones around farms were relatively small (mean area of 0.04-0.2 km), however deltamethrin impact zones covered much larger areas (mean area of 21.1-39.0 km). These findings suggest that deltamethrin poses a significant risk to European lobster in the Norwegian marine environment while the impact of azamethiphos may be less severe.
Topics: Animals; Aquaculture; Copepoda; Fish Diseases; Larva; Nephropidae; Nitriles; Norway; Organothiophosphates; Pesticides; Phthiraptera; Pyrethrins
PubMed: 32388310
DOI: 10.1016/j.envpol.2020.114725 -
Carcinogenesis Jun 2015An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are... (Review)
Review
An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression.
Topics: Animals; Environment; Hazardous Substances; Humans; Immune Evasion; Immunologic Surveillance; Neoplasms
PubMed: 26002081
DOI: 10.1093/carcin/bgv033 -
PloS One 2015Acetylcholinesterase (AChE) is the primary target for organophosphates (OP). Several mutations have been reported in AChE to be associated with the reduced sensitivity...
Acetylcholinesterase (AChE) is the primary target for organophosphates (OP). Several mutations have been reported in AChE to be associated with the reduced sensitivity against OP in various arthropods. However, to the best of our knowledge, no such reports are available for Lepeophtheirus salmonis. Hence, in the present study, we aimed to determine the association of AChE(s) gene(s) with resistance against OP. We screened the AChE genes (L. salmonis ace1a and ace1b) in two salmon lice populations: one sensitive (n=5) and the other resistant (n=5) for azamethiphos, a commonly used OP in salmon farming. The screening led to the identification of a missense mutation Phe362Tyr in L. salmonis ace1a, (corresponding to Phe331 in Torpedo californica AChE) in all the samples of the resistant population. We confirmed the potential role of the mutation, with reduced sensitivity against azamethiphos in L. salmonis, by screening for Phe362Tyr in 2 sensitive and 5 resistant strains. The significantly higher frequency of the mutant allele (362Tyr) in the resistant strains clearly indicated the possible association of Phe362Tyr mutation in L. salmonis ace1a with resistance towards azamethiphos. The 3D modelling, short term survival experiments and enzymatic assays further supported the imperative role of Phe362Tyr in reduced sensitivity of L. salmonis for azamethiphos. Based on all these observations, the present study, for the first time, presents the mechanism of resistance in L. salmonis against azamethiphos. In addition, we developed a rapid diagnostic tool for the high throughput screening of Phe362Tyr mutation using High Resolution Melt analysis.
Topics: Alleles; Animals; Base Sequence; Biological Assay; Codon; Crustacea; Drug Resistance; Female; Genotype; Homozygote; Molecular Sequence Data; Mutation, Missense; Organophosphates; Organothiophosphates; Phenotype; Polymorphism, Genetic; Salmon; Sequence Homology, Nucleic Acid
PubMed: 25893248
DOI: 10.1371/journal.pone.0124220 -
PloS One 2017Resistance towards antiparasitic agents in the salmon louse (Lepeophtheirus salmonis) is a widespread problem along the Norwegian coast, reducing treatments efficacies...
Resistance towards antiparasitic agents in the salmon louse (Lepeophtheirus salmonis) is a widespread problem along the Norwegian coast, reducing treatments efficacies and slowing down the envisioned expansion of Norwegian salmon production. The present study was conducted in order to assess the efficacies of two of the most widely used anti-parasitic substances-azamethiphos and deltamethrin-as well as assessing the benefit of having a resistant genotype compared to being fully sensitive when exposed to one of these substances. Atlantic salmon were exposed to a mix of salmon lice copepodids from a fully sensitive, a double resistant and a multi-resistant strain. Once the lice reached pre-adult stages, one group was exposed to 100 μg/L azamethiphos for 60 minutes, the other to 2 μg/L deltamethrin for 30 minutes, and the last was kept in a seawater control. Detached lice were collected at a series of time points following exposure, and all lice (immobilized and surviving) were analysed for both pyrethroid (sensitive "S" and resistant "R") and azamethiphos (fully sensitive "SS", heterozygous resistant "RS" and fully resistant "RR") resistance markers. We found that the efficacies of deltamethrin on parasites with genotype S and R were 70.3 and 13.2%, respectively. The overall efficacy of the deltamethrin treatment was 32.3%. The efficacies of azamethiphos on parasites with genotype SS, RS and RR were 100, 80 and 19.1%, respectively. The overall efficacy of the azamethiphos treatment was 80.4%. Survival analyses revealed that the median survival time in deltamethrin-sensitive and-resistant parasites were 16.8 and >172 hours, respectively. The differences were even more pronounced in the azamethiphos-treated group, where SS, RS and RR parasites survived for 0.26, 6.6 and >172 hours, respectively. The substantial differences in survival between sensitive and resistant lice following treatment demonstrate the ability of medicinal treatments to drive genetic selection towards a much more resistant salmon lice population within a very short time span if there is no influx of sensitive genotypes.
Topics: Animals; Copepoda; Drug Resistance; Genotype; Nitriles; Organophosphates; Organothiophosphates; Pyrethrins; Salmo salar
PubMed: 28531206
DOI: 10.1371/journal.pone.0178068 -
Scientific Reports Nov 2019Despite its widespread use in aquaculture, the impact of chemical anti-sea lice treatment on salmonids following application in a commercial farm has not been previously...
Despite its widespread use in aquaculture, the impact of chemical anti-sea lice treatment on salmonids following application in a commercial farm has not been previously reported. This work reports the cumulative effect of three consecutive anti-sea lice treatments using azamethiphos on the health status of aquaculture reared rainbow trout through the investigation of clinical chemistry, histopathology and proteome expression. The serum biomarkers showed decreasing trends in total protein, albumin and potassium concentrations and an average increase of total bilirubin and phosphate concentration towards the end of the treatment period. Principal component analysis clearly distinguished correlated pairs of biomarkers and also demonstrates a shift from acute to chronic effects as treatment progresses. Proteomic analysis confirmed alterations of proteins involved in clot formation, immune reaction and free heme binding. Tissue damage after the series of delousing treatments, exhibited increased deposits of hemosiderin. Results from this study suggest an impact of azamethiphos on trout health through intravascular haemolysis and consequently from pathophysiologic process of haemoglobin metabolism and its products, causing chronic kidney injury from iron deposits. This is the first report to demonstrate in fish the impact of active iron accumulation in different organs from physiological processes that can seriously impair normal function.
Topics: Animals; Aquaculture; Copepoda; Health; Oncorhynchus mykiss; Organothiophosphates; Proteomics; Seawater
PubMed: 31700034
DOI: 10.1038/s41598-019-52636-1 -
International Journal of Molecular... Nov 2022is the main ectoparasite that affects the salmon industry in Chile. The mechanisms used by the parasite to support its life strategy are of great interest for...
is the main ectoparasite that affects the salmon industry in Chile. The mechanisms used by the parasite to support its life strategy are of great interest for developing control strategies. Due to the critical role of insect peritrophins in host-parasite interactions and response to pest control drugs, this study aimed to identify and characterize the peritrophin-like genes present in . Moreover, the expression of peritrophin-like genes was evaluated on parasites exposed to delousing drugs such as pyrethroids and azamethiphos. Peritrophin genes were identified by homology analysis among the sea louse transcriptome database and arthropods peritrophin-protein database obtained from GenBank and UniProt. Moreover, the gene loci in the parasite genome were located. Furthermore, peritrophin gene expression levels were evaluated by RNA-Seq analysis in sea louse developmental stages and sea lice exposed to delousing drugs deltamethrin, cypermethrin, and azamethiphos. Seven putative peritrophin-like genes were identified in with high homology with other crustacean peritrophins. Differences in the presence of signal peptides, the number of chitin-binding domains, and the position of conserved cysteines were found. In addition, seven peritrophin-like gene sequences were identified in the genome. Gene expression analysis revealed a stage-dependent expression profile. Notably, differential regulation of peritrophin genes in resistant and susceptible populations to delousing drugs was found. These data are the first report and characterization of peritrophin genes in the sea louse , representing valuable knowledge to understand sea louse biology. Moreover, this study provides evidence for a deeper understanding of the molecular basis of response to delousing drugs.
Topics: Animals; Copepoda; Organothiophosphates; Salmon; Phthiraptera; Fish Diseases
PubMed: 36362121
DOI: 10.3390/ijms232113341