ABSTRACT
The most economically significant ectoparasites in the tropics and subtropics are ixodid ticks, especially Rhipicephalus annulatus and Rhipicephalus sanguineus. Years of extensive use of the readily available acaricides have resulted in widespread resistance development in these ticks, as well as negative environmental consequences. Benzyl alcohol (BA) has been frequently used to treat pediculosis and scabies, and it may be an effective alternative to commonly used acaricides. The main aim of the present study was to evaluate the acaricide activity of BA and its combination with the regularly used chemical acaricides against R. annulatus and R. sanguineus. Different concentrations of BA alone and in combination with deltamethrin, cypermethrin and chlorpyrifos were tested in vitro against adult and larvae of both tick species. The results showed that BA is toxic to R. annulatus and R. sanguineus larvae, with 100% larval mortality at concentrations of ≥50 mL/L, and LC50 and LC90 attained the concentrations of 19.8 and 33.8 mL/L for R. annulatus and 18.8 and 31.8 mL/L for R. sanguineus, respectively. Furthermore, BA in combination with deltamethrin, cypermethrin and chlorpyrifos exhibited synergistic factors of 2.48, 1.26 and 1.68 against R. annulatus larvae and 1.64, 11.1 and 1.14 against R. sanguineus larvae for deltamethrin + BA, cypermethrin + BA and chlorpyrifos + BA, respectively. BA induced 100% mortality in adult R. annulatus at concentrations of ≥250 mL/L with LC50 and LC90 reached the concentrations of 111 and 154 mL/L, respectively. Additionally, BA had ovicidal activity causing complete inhibition of larval hatching at 100 mL/L. The combination of BA with deltamethrin and cypermethrin increased acetylcholinesterase inhibition, whereas the combination of BA with chlorpyrifos decreased glutathione (GSH) activity and malondialdehyde levels. In the field application, the combination of BA 50 mL/L and deltamethrin (DBA) resulted in a significant reduction in the percentage of ticks by 30.9% 28 days post-treatment when compared with groups treated with deltamethrin alone. In conclusion, BA causes mortality in laboratory and field studies alone and in combination with cypermethrin or deltamethrin. BA can be used for control of ticks of different life stages, that is, eggs and larvae, through application to the ground.
Subject(s)
Acaricides , Chlorpyrifos , Nitriles , Pyrethrins , Rhipicephalus sanguineus , Rhipicephalus , Animals , Acaricides/pharmacology , Benzyl Alcohol/pharmacology , Chlorpyrifos/pharmacology , Acetylcholinesterase/pharmacology , LarvaABSTRACT
The present study evaluated the acaricidal activity of three Serratia strains isolated from Mimosa pudica nodules in the Lancandon zone Chiapas, Mexico. The analysis of the genomes based on the Average Nucleotide Identity, the phylogenetic relationships allows the isolates to be placed in the Serria ureilytica clade. The size of the genomes of the three strains is 5.4 Mb, with a GC content of 59%. The Serratia UTS2 strain presented the highest mortality with 61.41% against Tyrophagus putrescentiae followed by the Serratia UTS4 strain with 52.66% and Serratia UTS3 with 47.69% at 72 h at a concentration of 1X109 cell/mL. In the bioinformatic analysis of the genomes, genes related to the synthesis of chitinases, proteases and cellulases were identified, which have been reported for the biocontrol of mites. It is the first report of S. ureilytica with acaricidal activity, which may be an alternative for the biocontrol of stored products with high fat and protein content.
Subject(s)
Acaricides , Phylogeny , Serratia , Animals , Serratia/genetics , Acaricides/pharmacology , Genome, Bacterial , Pest Control, Biological , Chitinases/genetics , Chitinases/metabolism , MexicoABSTRACT
The brown dog tick or Rhipicephalus sanguineus sensu lato is an ixodid tick, responsible for the dissemination of pathogens that cause canine infectious diseases besides inflicting the direct effects of tick bite. The hot humid climate of Kerala, a south Indian state, is favorable for propagation of tick vectors and acaricides are the main stay of tick control. Though the resistance against synthetic pyrethroids is reported among these species, the status of amitraz resistance in R. sanguineus s. l. in the country is uncertain due to the lack of molecular characterisation data and scarce literature reports. Hence the present study was focused on the phenotypic detection and preliminary genotypic characterisation of amitraz resistance in the R. sanguineus s. l. A modified larval packet test (LPT) on a susceptible isolate was performed to determine the discriminating dose (DD). Further LPT-DD on 35 tick isolates was carried out to detect amitraz resistance robustly, along with that full dose response bioassays on the resistant isolates were performed. The results indicated that amitraz resistance is prevalent with 49 per cent of the samples being resistant. Amplification of exon 3 of octopamine receptor gene from both the susceptible and resistant larval isolates was carried out. Amplicons of ten pooled amitraz susceptible and ten pooled amitraz resistant representative samples were sequenced and analysed, unveiling a total of three novel non-synonymous mutations in the partial coding region at positions V32A, N41D and V58I in phenotypically resistant larval DNA samples. In silico analysis by homology modelling and molecular docking of the mutated and unmutated receptors showed that these mutations had reduced the binding affinity to amitraz. However, lack of mutations in the octopamine receptor gene in three of the pooled low order resistant R. sanguineus s. l. larval samples could be suggestive of other mechanisms associated with amitraz resistance in the region. Hence, further association studies should be carried out to confirm the association of these mutations with target insensitivity in R. sanguineus s. l. ticks, along with exploring the status of metabolic resistance and other mechanisms of resistance.
Subject(s)
Acaricides , Receptors, Biogenic Amine , Rhipicephalus sanguineus , Toluidines , Animals , Toluidines/pharmacology , Receptors, Biogenic Amine/genetics , India , Rhipicephalus sanguineus/genetics , Rhipicephalus sanguineus/drug effects , Acaricides/pharmacology , Larva/genetics , Larva/drug effects , Insecticide Resistance/genetics , Polymorphism, Genetic , Genotype , Dogs , Female , Dog Diseases/parasitology , Molecular Docking Simulation , Amino Acid Sequence , Biological AssayABSTRACT
The cattle tick Rhipicephalus microplus is an ectoparasite of high importance in veterinary medicine and public health. Since synthetic chemicals used to control these ticks can select resistant strains and cause toxic effects in their hosts, there is a need to identify effective substances with fewer adverse effects. For this reason, we investigated the effects of alpha- and beta-pinene, known for their various biological effects, on the mortality and reproductive performance of R. microplus engorged female ticks. The products were diluted in a 2% Tween 80 aqueous solution. The ticks were first weighed and then immersed in the test solutions for five minutes. Then, they were dried with paper towels and fixed dorsoventrally in Petri dishes, totalling five treatment groups for each pinene and a control group treated with the solvent alone. The ticks were monitored daily for mortality, and their eggs were collected and weighed. The larval hatching rate was estimated, and the pre-oviposition and incubation periods were determined. From these data, the following parameters were calculated: egg production index, fertility rate, estimated reproduction rate, percentages of reduction in oviposition and hatching, and product efficacy. Alpha-pinene showed better results at higher concentrations, unlike beta-pinene, which was more effective at lower concentrations. The effectiveness of alpha-pinene was 74% at a concentration of 14.0 µL/mL, while beta-pinene showed 78% efficacy at 2.0 µL/mL. The results indicated for the first time different effects of two isomers in ticks, suggesting that these compounds act on R. microplus females in different ways.
Subject(s)
Acaricides , Bicyclic Monoterpenes , Ixodidae , Rhipicephalus , Animals , Female , Oviposition , Acaricides/pharmacology , LarvaABSTRACT
The present study investigated the effect of ivermectin and amitraz on the cellular architecture of vital organs of Rhipicephalus microplus. Adult female ticks were treated with lethal concentrations (LC95) of ivermectin and amitraz, and the ovaries, synganglion, and Gené's organ were processed 48 h post treatment. In both the treatment groups, the ultra-thin sections of ovary exhibited deformed oocytes, irregular plasmic membrane and chorion layer, extensive vacuolation in the cytoplasm mainly at periphery of the cell and oocyte-pedicel junction. Marked vacuolations in the cortex and neuropile region with significant structural disorganization of the neural fibers were common alterations observed in the synganglion of ticks exposed to ivermectin and amitraz. The tissue sections of Gené's organ revealed deformed tubular glands with severe loss of cellular limit of secretory epithelium and cytoplasmic vacuolations in the ivermectin treated ticks whereas, the alterations were comparatively less severe in amitraz exposed ticks. The cellular deformities in these vital organs probably impaired reproductive function, nerve signal transmission and metabolic activities and thus affected fecundity and survivability of the treated ticks. The findings suggested that the action of ivermectin and amitraz are not restricted to the nervous system of ticks, but also on other vital organs, ovary and Gené's organ affecting the oviposition. The study provided insights into the development of targeted interventions for tick control strategies.
Subject(s)
Ivermectin , Ovary , Rhipicephalus , Toluidines , Animals , Ivermectin/pharmacology , Female , Rhipicephalus/drug effects , Toluidines/pharmacology , Ovary/drug effects , Acaricides/pharmacology , Microscopy, Electron, TransmissionABSTRACT
This study examined the pattern of resistance to widely applied synthetic pyrethroids, i.e., cypermethrin and deltamethrin, against larvae of Rhipicephalus microplus ticks sampled from Marathwada region in Maharashtra, India. The study also examined the role of α- and ß-esterases and glutathione-S-transferase (GST) in resistance development. All eight R. microplus isolates tested were resistant to deltamethrin (RL IV), having RR50 values from 6.88 to 131.26. LPT analysis exhibited the resistance level II deltamethrin resistance in Beed and Hingoli, III in Dharashiv, and IV in Sambhajinagar, Parbhani, Latur, Jalna, and Nanded isolates. The LIT analysis showed that Dharashiv field isolates had the lowest LC50 value of 229.09 ppm against cypermethrin, while Sambhajinagar field isolates had the highest at 489.78 ppm. The RR50 ranged from 1145.45 to 2448.9. Seven isolates were level I resistant to cypermethrin while the Jalna isolate was level II resistant. In larvae treated with deltamethrin and cypermethrin, the activity of α- and ß-esterase enzymes increased significantly compared to control groups. The enzyme ratios in treated larvae ranged from 0.7533 to 1.7023 for α-esterase and 0.7434 to 3.2054 for ß-esterase. The Hingoli isolate treated with cypermethrin exhibited the highest α-esterase activity (903.261), whereas Sambhajinagar isolate had the highest GST enzyme ratio (2.8224) after deltamethrin exposure. When exposed to cypermethrin, the Hingoli isolate showed the highest GST enzyme ratio, 2.0832. The present study provides the current resistance status in tick populations from Marathwada region indicating deltamethrin and cypermethrin to be ineffective for tick control. The results also suggest that SP compounds should be regulated in this region and alternative control strategies should be introduced.
Subject(s)
Acaricides , Glutathione Transferase , Larva , Nitriles , Pyrethrins , Rhipicephalus , Animals , Pyrethrins/pharmacology , India , Rhipicephalus/drug effects , Rhipicephalus/enzymology , Nitriles/pharmacology , Larva/drug effects , Glutathione Transferase/metabolism , Acaricides/pharmacology , Esterases/metabolism , Insecticide Resistance , Drug ResistanceABSTRACT
The citrus red mite, Panonychus citri, is one of the most notorious and devastating citrus pests around the world that has developed resistance to multiple chemical acaricides. In previous research, we found that spirodiclofen-resistant is related to overexpression of P450, CCE, and ABC transporter genes in P. citri. However, the regulatory mechanisms of these detoxification genes are still elusive. This study identified all hormone receptor 96 genes of P. citri. 8 PcHR96 genes contained highly conserved domains. The expression profiles showed that PcHR96h was significantly upregulated in spirodiclofen resistant strain and after exposure to spirodiclofen. RNA interference of PcHR96h decreased expression of detoxification genes and increased spirodiclofen susceptibility in P. citri. Furthermore, molecular docking, heterologous expression, and drug affinity responsive target stability demonstrated that PcHR96h can interact with spirodiclofen in vitro. Our research results indicate that PcHR96h plays an important role in regulating spirodiclofen susceptibility and provides theoretical support for the resistance management of P. citri.
Subject(s)
Spiro Compounds , Animals , Spiro Compounds/pharmacology , Spiro Compounds/metabolism , Acaricides/pharmacology , Propionates/pharmacology , Propionates/metabolism , Tetranychidae/drug effects , Tetranychidae/genetics , Tetranychidae/metabolism , Molecular Docking Simulation , Arthropod Proteins/genetics , Arthropod Proteins/metabolism , Drug Resistance/genetics , 4-Butyrolactone/analogs & derivativesABSTRACT
Haemaphysalis longicornis, which is widely distributed in China, can transmit various tick-borne diseases such as severe fever with thrombocytopenia syndrome, babesiosis, rickettsia disease and so on, and do great harm to human health and the development of animal husbandry. Chemical acaricides are the most traditional tick control method, but because of its many shortcomings, there is an urgent need to find a substitute with high efficiency, environmental protection and low toxicity. It has been found that some plant essential oils (EOs) have good insecticidal activity and environmental safety. In this study, the components of EOs from Pimenta racemosa and Eugenia caryophyllata were analyzed by gas chromatography-mass spectrometry (GC-MS), and their potential for application in the control of Haemaphysalis longicornis were studied. Gas chromatography-mass spectrometry analysis showed that the main components of P. racemosa EO were eugenol (64.07%), those of E. caryophyllata EO were Hexadecanoic acid, 2-methylpropyl ester (51.84%) and eugenol (39.76%). Larval packet test showed that the EOs of P. racemosa and E. caryophyllata had significant acaricidal activity against unfed larvae of H. longicornis, with LC50 values of 1.20 mg/mL and 0.47 mg/mL and LC90 values of 8.76 mg/mL and 2.91 mg/mL, respectively. The P. racemosa EO, E. caryophyllata EO and eugenol showed significant acaricidal activity against unfed nymph H. longicornis, with LC50 values of 1.65 mg/mL, 2.29 mg/mL and 0.93 mg/mL and LC90 values of 5.03 mg/mL, 11.01 mg/mL and 4.77 mg/mL, respectively. The P. racemosa EO, E. caryophyllata EO and eugenol showed significant acaricidal activity against unfed adults H. longicornis, with LC50 values of 0.51 mg/mL, 2.57 mg/mL and 1.83 mg/mL and LC90 values of 2.44 mg/mL, 11.44 mg/mL and 2.54 mg/mL, respectively. Enzyme assays revealed that the E. caryophyllata EO and eugenol significantly inhibited the activity of carboxylesterase (CarE), eugenol significantly inhibited the activity of catalase (CAT), and two EOs and eugenol had no significant effect on acetylcholinesterase (AchE) (p < 0.05). The above results suggest that the essential oils from P. racemosa and E. caryophyllata have great potential for use as alternatives to synthetic acaricides for tick control.
Subject(s)
Acaricides , Eugenia , Ixodidae , Larva , Oils, Volatile , Pimenta , Animals , Oils, Volatile/pharmacology , Oils, Volatile/chemistry , Ixodidae/drug effects , Acaricides/pharmacology , Eugenia/chemistry , Pimenta/chemistry , Larva/drug effects , Gas Chromatography-Mass Spectrometry , Plant Oils/pharmacology , Plant Oils/chemistry , Eugenol/analogs & derivatives , Eugenol/pharmacology , Haemaphysalis longicornisABSTRACT
Amblyomma sculptum is a species of tick in the family Ixodidae, with equids and capybaras among its preferred hosts. In this study, the acaricidal activity of the essential oil (EO) from Piper aduncum and its main component, Dillapiole, were evaluated against larvae of A. sculptum to establish lethal concentration values and assess the effects of these compounds on tick enzymes. Dillapiole exhibited slightly greater activity (LC50 = 3.38 mg/mL; 95% CI = 3.24 to 3.54) than P. aduncum EO (LC50 = 3.49 mg/mL; 95% CI = 3.36 to 3.62) against ticks. The activities of α-esterase (α-EST), ß-esterase (ß-EST), and glutathione-S-transferase (GST) enzymes in A. sculptum larvae treated with Dillapiole showed a significant increase compared to the control at all concentrations (LC5, LC25, LC50 and LC75), similar results were obtained with P. aduncum EO, except for α-EST, which did not differ from the control at the highest concentration (LC75). The results of the acetylcholinesterase (AChE) activity show an increase in enzyme activity at the two lower concentrations (LC5 and LC25) and a reduction in activity at the two higher, lethal concentrations (LC50 and LC75) compared to the control. These results suggest potential mechanisms of action for these natural acaricides and can provide guidance for the future development of potential plant-derived formulations.
Subject(s)
Acaricides , Acetylcholinesterase , Amblyomma , Oils, Volatile , Piper , Animals , Acaricides/pharmacology , Acetylcholinesterase/metabolism , Allyl Compounds , Amblyomma/drug effects , Amblyomma/growth & development , Benzodioxoles/pharmacology , Cholinesterase Inhibitors/pharmacology , Dioxoles , Esterases/metabolism , Glutathione Transferase/metabolism , Inactivation, Metabolic , Larva/drug effects , Oils, Volatile/pharmacology , Oils, Volatile/chemistry , Piper/chemistryABSTRACT
Varroosis induced by Varroa destructor Anderson and Trueman represents the most pathogenic and destructive disease affecting the western honey bee, Apis mellifera. In this study, we investigated the acaricidal activity against the Varroa mite using essential oils (EOs) from the aerial parts of four autochthonous Algerian herbal species, namely Artemisia herba alba, Artemisia campestris, Artemisia judaica and Ruta montana. EOs were obtained by means of hydrodistillation and their composition was characterized by gas chromatography-mass spectrometry. The toxicity of the selected EOs toward V. destructor and A. mellifera adult honey bees was evaluated using the complete exposure method. The results indicate the predominance of davanone (66.9%) in A. herba alba, ß-pinene (19.5%) in A. campestris, piperitone (68.7%) in A. judaica and 2-undecanone (70.1%) in R. montana EOs. Interestingly, the LC50 values coupled to bee mortality rates revealed that all tested oils exhibited significant acaricidal efficiency with selectivity ratio (SR) values of 10.77, 8.78, 5.62 and 3.73 for A. campestris, A. judaica, A. herba alba, and R. montana, respectively. These values were better than that of thymol (SR = 3.65), the positive control. These findings suggest that these EOs could be used as plant-derived veterinary acaricides to control varroosis in field conditions.
Subject(s)
Acaricides , Oils, Volatile , Varroidae , Bees , Animals , Oils, Volatile/pharmacology , Oils, Volatile/chemistry , Acaricides/pharmacology , ThymolABSTRACT
The aim of this research was to investigate the larvicidal and repellent effects of essential oils (EOs) obtained from two Lamiaceae plant species, Origanum minutiflorum O. Schwarz & P.H. Davis and Dorystoechas hastata Boiss. & Heldr. ex Bentham, both endemic to Turkey, on Rhipicephalus sanguineus s.l. Latreille (Acari: Ixodidae). The study also introduces a new test method that can be used to assess the repellent effects against ticks. Both plant EOs exhibited the highest larvicidal activity against brown dog tick larvae after 24 h and LC50 and LC90 values were determined as 0.101% and 0.125% for O. minutiflorum essential oil and 0.937% and 2.1% for D. hastata essential oil, respectively. In this study, we have described a detailed protocol for a novel larval repellent activity test (LRAT) for essential oils and extracts, using simple equipment. The advantages and limitations of LRAT, when compared to other tests commonly used to determine repellent effect against ticks, are also included in this study. The LRAT was developed with modifications of the larval immersion test (LIT) and proves to be a highly efficient and easily observable method. It can be used to test any active substance that may be toxic to humans and animals. According to the LRAT, at the end of 3 h, O. minutiflorum essential oil showed a high repellent effect, varying between 84.14% and 100% at 1% concentration. This result was not statistically different from the DEET, the positive control. When comparing the larvicidal and repellent activities, O. minutiflorum essential oil was found to be more effective than D. hastata essential oil.
Subject(s)
Acaricides , Insect Repellents , Ixodidae , Oils, Volatile , Rhipicephalus sanguineus , Rhipicephalus , Dogs , Humans , Animals , Oils, Volatile/pharmacology , Larva , Insect Repellents/pharmacology , Acaricides/pharmacologyABSTRACT
Rhipicephalus (Boophilus) microplus, an invasive species to Africa, and the endemic R. (B.) decoloratus are of high economic importance in the cattle industry. Invasion of the alien species in South Africa has mostly been reported for traditional communal grazing areas where it seemed to be rapid and, in some cases, even replaced the native species. The alien species is also assumed to already be resistant to acaricides upon invasion. The presence of R. (B.) microplus on commercial farms was therefore investigated and resistance screening of both species to field concentrations of cypermethrin, amitraz, and chlorfenvinphos was determined by means of the larval immersion test. Results showed that only 3.7% (of 383) tick collections submitted were R. (B.) microplus populations. A further 1.6% (of 383) showed co-existence of the two species. Comparing the level of resistance to the acaricides between the two species indicated a mean phenotypic resistance of 66.2 and 26.5% of R. (B.) decoloratus populations to cypermethrin and amitraz, respectively. This was significantly lower for R. (B.) microplus, with 23.0 and 4.1% of its populations resistant to cypermethrin and amitraz, respectively. Closed commercial farming areas seemed to have a preventative advantage for the invasion of R. (B.) microplus and displacement of R. (B.) decoloratus by R. (B.) microplus. Regular monitoring of these two species may be of high importance to prevent unnecessary financial losses due to insufficient control and increased awareness of the threat of Asiatic babesiosis vectored by R. (B.) microplus.
Subject(s)
Acaricides , Cattle Diseases , Pyrethrins , Rhipicephalus , Tick Infestations , Toluidines , Animals , Cattle , Acaricides/pharmacology , Farms , South Africa/epidemiology , Tick Infestations/veterinary , Cattle Diseases/epidemiologyABSTRACT
Varroa destructor Anderson & Trueman (Acari: Varroidae) is of paramount significance in modern beekeeping, with infestations presenting a primary challenge that directly influences colony health, productivity, and overall apicultural sustainability. In order to control this mite, many beekeepers rely on a limited number of approved synthetic acaricides, including the pyrethroids tau-fluvalinate, flumethrin and organophosphate coumaphos. However, the excessive use of these substances has led to the widespread development of resistance in various beekeeping areas globally. In the present study, the occurrence of resistance mutations in the voltage-gated sodium channel (VGSC) and acetylcholinesterase (AChE), the target-site of pyrethroids and coumaphos, respectively, was examined in Varroa populations collected throughout the southeastern and eastern Anatolia regions of Türkiye. All Varroa samples belonged to the Korean haplotype, and a very low genetic distance was observed based on cytochrome c oxidase subunit I (COI) gene sequences. No amino acid substitutions were determined at the key residues of AChE. On the other hand, three amino acid substitutions, (L925V/I/M), previously associated with pyrethroid resistance, were identified in nearly 80% of the Turkish populations. Importantly, L925M, the dominant mutation in the USA, was detected in Turkish Varroa populations for the first time. To gain a more comprehensive perspective, we conducted a systematic analysis of the distribution of pyrethroid resistance mutations across Europe, based on the previously reported data. Varroa populations from Mediterranean countries such as Türkiye, Spain, and Greece exhibited the highest frequency of resistance mutation. Revealing the occurrence and geographical distribution of pyrethroid resistance mutations in V. destructor populations across the country will enhance the development of more efficient strategies for mite management.
Subject(s)
Acaricides , Mutation , Pyrethrins , Varroidae , Varroidae/genetics , Varroidae/physiology , Animals , Pyrethrins/pharmacology , Acaricides/pharmacology , Turkey , Arthropod Proteins/genetics , Insecticide Resistance/genetics , Acetylcholinesterase/genetics , Acetylcholinesterase/metabolism , Drug Resistance/genetics , Voltage-Gated Sodium Channels/geneticsABSTRACT
Acaricides used against Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) in cotton fields cause control failure over time. To determine the resistance status of T. urticae populations to tebufenpyrad and bifenazate, different populations collected from Aydin (AYD), Adana (ADA), Sanliurfa (SAN), and Diyarbakir (DIY) provinces of Türkiye, between 2019 and 2020, were subjected to diagnostic dose bioassays. Firstly, the spider mites were eliminated with a discriminating dose. Afterwards, LC50 and LC90 of the remaining populations were determined and the ten highest resistant populations were selected. The highest phenotypic resistance to bifenazate was observed in AYD4 and DIY2 (LC50 57.14 mg L- 1 with 85.01-fold and LC50 30.15 mg L- 1with 44.86-fold, respectively), while the lowest phenotypic resistance was found in SAN6 (LC50 1.5 mg L- 1; 2.28-fold). Considering the phenotypic resistance to tebufenpyrad, the highest resistance was found in AYD4 population (LC50 96.81 mg L- 1; 12.92-fold), while the lowest - in DIY28 population (LC50 21.23 mg L- 1; 2.83-fold). In pharmacokinetic studies, the ADA16 population was compared with the sensitive German Susceptible Strain population and it was determined that carboxylesterase activity was statistically higher (1.46 ± 0.04 nmol/min/mg protein enzyme activation 2.70-fold). The highest activation of glutathione S-transferase was detected in ADA16 (1.49 ± 0.01 nmol/min/mg protein; 2.32-fold). No mutations were found in PSST (METI 1), the point mutation site for tebufenpyrad, and Cytb (METI 3), the point mutation site for bifenazate. In terms of phenotypic resistance, bifenazate was found to be moderately resistant in two populations (85.01 and 44.86-fold), while tebufenpyrad was moderately resistant in one population (12.92-fold). This study showed that both acaricides are still effective against T. urticae populations.
Subject(s)
Acaricides , Gossypium , Tetranychidae , Animals , Tetranychidae/drug effects , Tetranychidae/enzymology , Acaricides/pharmacology , Inactivation, Metabolic , Drug Resistance , Arthropod Proteins/metabolism , Arthropod Proteins/geneticsABSTRACT
The aim of this work was to analyze the R. microplus (Canestrini, 1888) infestation in two bovine herds with different degrees of natural resistance (i.e., Hereford and Braford) to ticks subjected to an identical chemical treatment scheme to ticks at the same farm, to demonstrate the impact on tick control of the incorporation of a more resistant bovine breed. Two groups of ten Hereford and Braford cows each were subjected to eleven chemical treatments between August 2022 and October 2023 (four fluazuron, two fipronil 1%, one ivermectin 3.15% and four immersion in a dipping vat with a combination of cypermethrin 10% and ethion 40%). Tick population was shown to be susceptible to ivermectin, fluazuron and the mix cypermethrin 10%-ethion 40% and resistant to fipronil according to in vitro tests. Tick infestation was significantly greater in the Hereford cows than in the Braford cows. Tick infestation in both Hereford and Braford breeds was similar when treatment with functional drugs was applied, but when a block of the treatments was done with drugs with decreased functionality due to resistance (i.e. fipronil), treatment failure was manifested more strongly in the most susceptible breed. The incorporation of cattle breeds with moderate or high resistance to R. microplus is instrumental to optimize the efficacy and sustainability of chemical control of ticks in a scenario where resistance to one or more chemical groups is almost ubiquitous, because it favors the biological control of this parasite.
Subject(s)
Acaricides , Cattle Diseases , Pyrazoles , Rhipicephalus , Tick Infestations , Animals , Cattle , Rhipicephalus/physiology , Rhipicephalus/drug effects , Tick Infestations/veterinary , Tick Infestations/parasitology , Acaricides/pharmacology , Cattle Diseases/parasitology , Cattle Diseases/drug therapy , Female , Pyrazoles/pharmacology , Ivermectin/pharmacology , Phenylurea Compounds/pharmacology , Tick Control , Pyrethrins/pharmacologyABSTRACT
Blood feeding and digestion are vital physiological activities essential for the survival and reproduction of ticks. Chemical acaricides viz., ivermectin, amitraz and fipronil, are known to act on the central nervous system, resulting in the mortality of ticks. The present study is focused on the effect of these acaricides on the midgut and gut enzymes of Rhipicephalus microplus. The ultra-thin sections of midgut of ivermectin-treated ticks showed irregular basal membrane and ruptured digestive vesicles. Amitraz treatment resulted in a notable decrease in digestive cells with pleats in the basal membrane, while fipronil-exposed ticks exhibited reduced digestive cells, loss of cellular integrity, and disintegration of the basal membrane and muscle layer. The gut tissue homogenate of ivermectin and fipronil treated ticks showed a significant reduction of cathepsin D level, 76.54 ± 3.20 µg/mL and 92.67 ± 3.72 µg/mL, respectively, as compared to the control group (150.0 ± 3.80 µg/mL). The leucine aminopeptidase level (4.27 ± 0.08 units/mL) was significantly decreased in the ivermectin treated ticks compared to other treatment groups. The acid phosphatase activity (29.16 ± 0.67 µmole/min/L) was reduced in the ivermectin treated group whereas, increased activity was observed in the fipronil and amitraz treated groups. All the treatment groups revealed increased alkaline phosphatase levels (17.47-26.72 µmole/min/L). The present finding suggests that in addition to the established mechanism of action of the tested acaricides on the nervous system, the alterations in the cellular profile of digestive cells and enzymes possibly affect the blood digestion process and thus the synthesis of vital proteins which are essential for vitellogenesis, and egg production in ticks.
Subject(s)
Acaricides , Ivermectin , Pyrazoles , Rhipicephalus , Toluidines , Animals , Rhipicephalus/drug effects , Rhipicephalus/physiology , Ivermectin/pharmacology , Pyrazoles/pharmacology , Toluidines/pharmacology , Acaricides/pharmacology , Female , Epithelium/drug effects , Gastrointestinal Tract/drug effectsABSTRACT
One of the most damaging pests of agricultural crops across the globe is the two-spotted spider mite, Tetranychus urticae Koch. A wide variety of arthropods and plant pathogens can be controlled by essential oils, which are secondary metabolites produced by plants. It is possible to enhance the stability as well as the anti-pest efficiency of plant essential oils by encapsulation. Water distillation was used to extract the essential oils from Eucalyptus globulus and Ferula assafoetida. The chitosan nanoparticles were used to load both essential oils into nanoformulations. Studies were conducted on T. urticae life table characteristics under experimental circumstances to determine the sublethal impacts of essential oils and their nanoformulations. Intrinsic growth rate (r) for population exposed to E. globulus, F. assafoetida essential oils, their nanoformulations and the control were 0.1, 0.069, 0.051, 0.018 and 0.21 per day, respectively. F. assafoetida and E. globulus nanoformulations resulted the lowest fecundity compared to the other treatments. According the result of the lethal and sublethal effects of purified essential oils and nanoformulations of F. assafoetida and E. globulus, they would be recommended for controlling the two-spotted spider mites, T. urticae.
Subject(s)
Acaricides , Eucalyptus , Ferula , Oils, Volatile , Tetranychidae , Animals , Tetranychidae/drug effects , Tetranychidae/growth & development , Eucalyptus/chemistry , Oils, Volatile/pharmacology , Ferula/chemistry , Acaricides/pharmacology , Female , Nanoparticles , Plant Oils/pharmacology , Male , Tick Control , Fertility/drug effects , Chitosan/pharmacologyABSTRACT
The main way to avoid contact with ticks and consequently tick-borne disease is the use of synthetic repellents. The search of new repellent compounds to increase the possibilities of use in strategies controls are necessary. The present study evaluated the repellent activity of two natural terpenes carvacrol and thymol in each one two different formulation (encapsulated and nonencapsulated with yeast cell wall) against the ticks Amblyomma sculptum and Rhipicephalus sanguineus sensu lato nymphs. Nymphs of A. sculptum and R. sanguineus s.l. of a single generation were used. The vertical filter paper repellency assay were performed with different concentration of both terpenes encapsulated and nonencapsulated in yeast cell wall. The repellent concentration 50% (RC50) were calculated to each compound formulation. Both carvacrol and thymol (encapsulated and nonencapsulated), had a repellent activity against A. sculptum and R. sanguineus s.l nymphs. Amblyomma sculptum was more sensitive to nonencapsulated carvacrol (RC50 values: 0.0032 to 0.0082 mg/cm2 after 1 and 15 min) (P < 0.05), while R. sanguineus s.l. was more sensitive to encapsulated carvacrol (RC50 values: 0.00008 to 0.0035 mg/cm2 after 1 and 15 min) (P < 0.05). Among tick species, R. sanguineus s.l. was more sensitive for most compounds than A. sculptum (P < 0.05). Although with distinct repellent activities, carvacrol and thymol encapsulated can be a promising alternative to synthetic repellents against A. sculptum and R. sanguineus s.l.
Subject(s)
Amblyomma , Cymenes , Nymph , Rhipicephalus sanguineus , Thymol , Cymenes/pharmacology , Animals , Thymol/pharmacology , Nymph/drug effects , Nymph/growth & development , Rhipicephalus sanguineus/drug effects , Cell Wall/drug effects , Acaricides/pharmacology , Monoterpenes/pharmacology , Insect Repellents/pharmacology , Saccharomyces cerevisiae/drug effectsABSTRACT
To study the acaricide resistance status and possible mechanisms of action in conferring resistance to commonly used acaricides (deltamethrin and coumaphos), Hyalomma anatolicum ticks were collected from 6 dairy farms of Hisar and Charkhi Dadri districts of Haryana. By using standard larval packet test, H. anatolicum tick larvae of Charkhi Dadri isolates were found to be susceptible (100% mortality) to both the acaricides. Level-I resistance against coumaphos was recorded from four isolates, whereas, level-II was observed in only one isolate, collected from Hisar. One isolates (Kaimri) from Hisar also showed level-I resistance against deltamethrin. Biochemically, the ticks having higher values of resistance factor (RF) against coumaphos were found to possess increased enzymatic activity of α-esterase, ß-esterase, glutathione-S-transferase (GST) and mono-oxygenase enzymes, whereas, the monoamine oxidase did not show any constant trend. However, the RF showed a statistical significant correlation with GST only. Native PAGE analysis of H. anatolicum ticks revealed the presence of nine types of esterases (EST-1 h to EST-9 h) by using napthyl acetate as substrate. In the inhibitory assay, esterases were found to be inhibited by PMSF, indicating the presence of serine residue at catalytic triad. The partial cds of carboxylesterase and domain II of sodium channel genes were sequenced to determine any proposed mutations in resistant isolates of H. anatolicum ticks, however, no mutations were observed in either gene, indicating that increased expression of detoxification enzymes as a possible mechanism for resistance development, in the current study.
Subject(s)
Acaricides , Coumaphos , Ixodidae , Nitriles , Pyrethrins , Animals , Pyrethrins/pharmacology , Nitriles/pharmacology , Acaricides/pharmacology , Ixodidae/drug effects , Ixodidae/genetics , Ixodidae/physiology , Coumaphos/pharmacology , Larva/growth & development , Larva/drug effects , India , Drug Resistance/genetics , Insecticide Resistance/genetics , Female , Esterases/metabolism , Esterases/geneticsABSTRACT
The control of the camel tick, Hyalomma dromedarii is very crucial. This study evaluated the novel toxicity of photosensitizers and Phoxim insecticide against H. dromedarii males using the adult immersion tests. Ticks were subjected to sunlight for 10 min post-treatment (PT). The optical characters of the applied materials were determined by UV-Vis spectroscopy (250-900 nm wavelengths). The intensity of spectra decreased as dye concentration decreased. The optical bandgap energies of the dyes at different concentrations were not changed as the concentration changed and decreased as the absorption peak of individual dyes red-shifted. The mortalities 72 h PT reached 42.2%, 44.4%, 51.1%, 71.1%, 46.7%, 48.9%, 44.4%, and 55.6% for chlorophyllin, echinochrome, field stain, methylene blue, phthalocyanine, rhodamine 6G, riboflavin, and safranin, respectively. Methylene blue recorded the highest median lethal concentration (LC50 = 127 ppm) followed by safranin, field stain, rhodamine 6G, phthalocyanine, echinochrome riboflavin, and chlorophyllin (LC50 = 209, 251, 271, 303, 324, 332, and 362 ppm, respectively, 72 h PT). Their median lethal time, LT50, values PT with 240 ppm were 45, 87, 96, 72, 129, 115, 131, and 137 h, respectively. The relative toxicities of the LC50 values 72 h PT showed that chlorophyllin, echinochrome, field stain, methylene blue, phthalocyanine, rhodamine 6G, riboflavin, and safranin were 3.2, 3.6, 4.6, 9.1, 3.8, 4.3, 3.5, and 5.6 times, respectively, more effective than Phoxim. Methylene blue, safranin, and field stain showed a broad absorbance area indicating a large photoactivity and better phototoxicity and could be used as alternative agents to synthetic acaricides.