Acaricidal Effect Research Articles

LABORATORY EVALUATION OF BIGSHOT MAXIM, REPELCARE, AND CLOVE ESSENTIAL OIL, SYZYGIUM AROMATICUM AGAINST THE LONE STAR TICK, AMBLYOMMA AMERICANUM

Synthetic acaricides have been the most used method for controlling tick populations. However, their frequent application has had negative impacts on treated animals and the environment and led to the development of resistance in tick populations. These factors generated interest and the need to find more environmentally friendly alternatives. In this study, the repellency and acaricidal effects of BigShot Maxim (AIs: cedarwood oil, cinnamon oil, thyme oil), RepelCare (AIs: turmeric oil and eucalyptus oil), and clove oil, Syzygium aromaticum L., were tested against the lone star tick, Amblyomma Americanum (Linnaeus). Despite no evidence of repellency for BigShot Maxim, RepelCare and clove oil, its disruption of the host seeking behavior after contact to the products was observed and further investigated. BigShot Maxim and clove oil were selected for mortality testing and resulted in complete mortality of male, female ticks, and nymphs with some application rates. The results from this study provide a better understanding of repellency and acaricidal effects of botanical products against the lone star tick that can be used to further improve the development of green chemistry. However, further studies are warranted before these botanical products can be implemented as effective alternatives to chemical acaricides to use in integrated vector control.

옥살산을 이용한 꿀벌 안전성과 꿀벌응애류 방제 효율 평가

This study investigated the safety of oxalic acid (natural acaricide), on honeybee ( Apis mellifera) colonies and its acaricidal effects on honeybee pest mites (Varroa destructor and Tropilaelaps mercedesae). To determine the safety and acaricidal effects of oxalic acid, the impacts of oxalic acid was examined using different treatment methods (i) fumigation and (ii) dripping (trickling), and concentrations (0.7, 3, and 6%). For the fumigation, 1 g of oxalic acid was treated inside the beehive, and the experimental groups were divided by blocking the entrance of the beehive for different durations (1, 5, 10, and 15 min.). For the dripping, oxalic acid-sugar solutions with different concentrations (0.7, 3, and 6%) were prepared and applied to the beehive to measure safety and efficacy of oxalic acid. The safety of honeybees with oxalic acid treatment showed no significant differences between the experimental and control groups for both the fumigation and dripping methods, and had no significant impact on the honeybee colonies. The acaricidal effect of oxalic acid treatment was higher against V. destructor in all experimental groups compared to the control group in the fumigation method. In the dripping method, only the experimental groups with 3 and 6% concentrations showed significant differences and demonstrated acaricidal effects compared to the control group. For T. mercedesae , the low number of detected individuals resulted in no significant effects. Both treatment methods did not show any significant acaricidal effects on V. destructor and T. mercedesae, which exist inside the capped brood cells.

In vitro nematicidal and acaricidal effect of biosurfactants produced by Bacillus against the root-knot nematode Nacobbus aberrans and the dust mite Tyrophagus putrescentiae.

In the present study, the nematicidal and acaricidal activity of three biosurfactants (BS) produced by strains of the Bacillus genus was evaluated. The BS produced by the Bacillus ROSS2 strain presented a mortality of 39.29% in juveniles (J2) of Nacobbus aberrans at a concentration of 30 mg/mL, this same strain is the one that presented the highest mortality in Tyrophagus putrescentiae, which was 57.97% at a concentration of 39 mg/mL. The BS were qualitatively identified by thin layer chromatography and are lipid in nature based on the retention factor (Rf). While the GC-MS analysis identified two main compounds that are 4,7-Methano-1H-indene-2,6-dicarboxylic acid, 3a,4,7,7a-tetrahydro-1, and Methyl 4-(pyrrol-1-yl)-1,2,5-oxadiazole-3-carboxylate1, which is the polar part indicated by the presence of dicarboxylic acid and carboxylate groups; while the non-polar portion can be interpreted as a hydrocarbon chain of variable length. Based on the present results, BS can be an alternative for the biocontrol of the root-knot nematode N. aberrans and the mite T. putrescentiae.

In Vitro and In Silico Protocols for the Assessment of Anti-Tick Compounds from Pinus roxburghii against Rhipicephalus (Boophilus) microplus Ticks.

Pinus roxburghii, also known by the name "Himalayan chir pine," belongs to the Pinaceae family. Rhipicephalus (Boophilus) microplus tick is one of the most significant bovine ectoparasites, making it a major vector of economically important tick-borne diseases. The researchers conducted adult immersion tests (AIT) and larval packet tests (LPT) to investigate the acaricidal effect of P. roxburghii plant extract on R. (B.) microplus and its potential modulatory function when used with cypermethrin. Eggs were also assessed for their weight, egg-laying index (IE), hatchability rate, and control rate. After exposure to essential extract concentrations ranging from 2.5 to 40 mg/mL for 48 h, adult female ticks' oviposition inhibition and unfed R. (B.) microplus larvae's mortality rates were analyzed. Engorged females exposed to P. roxburghii at 40 mg/mL had reduced biological activity (oviposition, IE) compared to positive and negative controls. A concentration of 40 mg/mL of P. roxburghii caused 90% mortality in R. (B.) microplus larvae, whereas cypermethrin (the positive control) caused 98.3% mortality in LPT. In AIT, cypermethrin inhibited 81% of oviposition, compared to the 40 mg/mL concentration of P. roxburghii, which inhibited 40% of the ticks' oviposition. Moreover, this study assessed the binding capacity of selected phytocompounds with the targeted protein. Three servers (SWISS-MODEL, RoseTTAFold, and TrRosetta) recreated the target protein RmGABACl's 3D structure. The modeled 3D structure was validated using the online servers PROCHECK, ERRAT, and Prosa. Molecular docking using Auto Dock VINA predicted the binding mechanisms of 20 drug-like compounds against the target protein. Catechin and myricetin showed significant interactions with active site residues of the target protein, with docking scores of -7.7 kcal/mol and -7.6 kcal/mol, respectively. In conclusion, this study demonstrated the acaricidal activity of P. roxburghii extract, suggesting its potential as an alternative natural acaricide for controlling R. (B.) microplus.

Poultry red mite eradication potential of ivermectin and allicin combination treatment.

Existing treatments against poultry red mite (PRM; Dermanyssus gallinae) infestation have reduced efficacy or exhibit hazardous effects on chickens. Considering the economic importance of chickens, development of a safe and effective method for exterminating PRMs is necessary. Ivermectin and allicin are effective against some ectoparasites; however, their acaricidal efficacies against PRMs remain unknown. To evaluate individual and combined efficacies of ivermectin and allicin in exterminating PRMs. Different concentrations (0.10-1.0mg/mL) of ivermectin (1mL) were applied via dropping method in different insect culture dishes (ICDs), prior to transferring PRMs. For the spraying method, PRMs were transferred to ICDs, before spraying ivermectin (1mg/mL) solution (1mL). Further, the acaricidal effect of allicin on PRMs was evaluated by applying different concentrations (0.25-1.0mg/mL) of allicin (1mL). The combined acaricidal effects of ivermectin and allicin were analysed using four concentration combinations. PRM death rates were determined after 2h, 24h, 2 days, 5 days and 7 days of drug application. Ivermectin application (1mg/mL) exterminated 64% and 100% of PRMs on 1 and 5 days, respectively, and prevented their revival. Further, 0.5mg/mL ivermectin and 1mg/mL allicin individually exterminated 98% and 44% of PRMs, respectively, within 7 days of treatment. In combination, 0.5mg/mL ivermectin and 0.5mg/mL allicin exterminated 100% of PRMs within 5 d of treatment. The most effective combination was 0.25mg/mL ivermectin + 1.00mg/mL allicin. The efficacy of ivermectin-allicin combination in exterminating PRMs was demonstrated. This novel approach could be optimised for industrial applications.

Acción ixodicida de productos naturales de plantas nativas mexicanas

This work determined the acaricidal effect of 18 Mexican plants against Rhipicephalus microplus. The results of the larvicidal assay revealed that 5 methanolic extracts produced high activity (86-100 % mortality), 3 extracts exhibited relatively high activity (71-85 % mortality), 2 extracts displayed moderate activity (56-70 % mortality), 2 extracts presented low activity (31-55 % mortality) and 6 extracts showed non-significant acaricidal activity (0-30 % mortality). Extracts inducing >56 % mortality were subsequently assayed against engorged ticks of R. microplus by adult immersion test at a concentration of 5.0% w/v. In general terms, the results on larvae and adult ticks indicated that the methanolic extracts of Annona globiflora, Annona scleroderma, Litchi chinensis and Azadirachta indica showed the greatest activities. The crude extract of A. indica was subjected to chromatographic purification, which has led to the isolation of 3-O-butyl-(-)-epigallocatechin (1), 3-O-butyl-(-)-epicatechin (2), (-)-epigallocatechin (3), (+)-gallocatechin (4), (-)-epicatechin (5), β-sitosterol (6), stigmasterol (7), stigmasterol glucoside (8), triolein (9), azadirachtin A (10), and the octadecanoic acid-tetrahydrofuran-3,4-vinyl ester (11). The isolated compounds' chemical structures were identified by the interpretation of NMR and HRESI-MS spectroscopic data. The isolated compounds were assayed against engorged ticks of R. microplus at a concentration of 6 mM. Based on the results obtained, it was concluded that 3-O-butyl-(-)-epigallocatechin (1), 3-O-butyl-(-)-epicatechin (2), azadirachtin A (10), and octadecanoic acid-tetrahydrofuran-3,4-vinyl ester (11) show the highest effectiveness.

Acaricidal action of ozone on larvae and engorged females of Rhipicephalus microplus: a dose-dependent relationship.

The tick Rhipicephalus microplus is a vector of infectious agents that causes great economic loss in the productivity of cattle herds. Several studies have sought natural compounds with acaricidal activity to control ticks, without allowing the development of resistance, without causing environmental damage, and without presenting toxicity to the hosts. The activity of ozone on the natural biomolecules of living beings has been studied as an alternative to control arthropods and acaricidal effects were shown on ticks. The aim of the present study was to assess the acaricidal effect on larvae and engorged females of R. microplus according to ozone dose. Larvae (n = 377) were distributed in 10 groups and engorged females (n = 284) were distributed in 14 groups. One group was used as control (not exposed to ozone) and the other groups were exposed to ozone gas for 5-105min. Ozone had a dose-dependent acaricidal effect on both larvae and engorged females. Dosages between 355 and 2130mg/L min had a delayed acaricidal effect (12-180h), leading to the death of all engorged females before laying eggs, whereas doses between 3195 and 7455mg/L min showed immediate acaricidal effect (5min to 4h). Doses between 1775 and 6390mg/L min had an immediate (up to 5min) acaricidal effect on the larvae of this species. Further studies should consider longer follow-up times during the assessment of the acaricidal activity against ticks.

Evaluation of the in vitro acaricidal effect of five organic compounds on the cattle fever tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The cattle fever tick, Rhipicephalus (Boophilus) microplus, is the most economically important tick worldwide. Infestations with this tick can lead to direct damage and cattle mortality due to the transmission of potentially deadly pathogens. Management of this tick species has been focused on the use of synthetical acaricides; however, the emergence of acaricide resistance to single or multiple active ingredients has resulted in a need for novel acaricide compounds. Among potential avenues for the discovery of novel acaricides are plant-derived compounds. The efficacy of five organic compounds (nootkatone, Stop the Bites®, BioUD®, lavender oil, and cedarwood oil) was evaluated using larval immersion tests (LITs), repellency assays, and adult immersion tests (AITs). The results from the LITs indicate that three of the organic compounds (NootkaShield™, Stop the Bites, BioUD) led to significant mortalities at low concentrations (0.2, 0.02, and 0.08%, respectively). By comparison, lavender and cedar oil led to around 90% mortality at 10 and 1% concentrations, respectively. Similarly, NootkaShield, Stop the Bites, and BioUD had strong repellent properties with over 90% repellency at the two highest concentrations tested. Using the FAO 2004 guidelines, we evaluated the effectiveness of these organic compounds at reducing the fecundity of R. (B.) microplus and show that Nootkatone, Stop the Bites, and BioUD may significantly decrease tick populations (Drummond’s index > 90% at concentrations of 5%), highlighting their potential as alternatives to synthetic acaricides for the control of cattle fever ticks.

Expression of β-glucosidase An-bgl3 from Aspergillus niger for conversion of scopolin

Scopoletin is a coumarin compound with various biological activities including detumescence and analgesic, insecticidal, antibacterial and acaricidal effects. However, interference with scopolin and other components often leads to difficulties in purification of scopoletin with low extraction rates from plant resource. In this paper, heterologous expression of the gene encoding β-glucosidase An-bgl3 derived from Aspergillus niger were carried out. The expression product was purified and characterized with further structure-activity relationship between it and β-glucosidase analyzed. Subsequently, its ability for transforming scopolin from plant extract was studied. The results showed that the specific activity of the purified β-glucosidase An-bgl3 was 15.22 IU/mg, the apparent molecular weight was about 120 kDa. The optimum reaction temperature and pH were 55 ℃ and 4.0, respectively. Moreover, 10 mmol/L metal ions Fe2+ and Mn2+ increased the enzyme activity by 1.74-fold and 1.20-fold, respectively. A 10 mmol/L solution containing Tween-20, Tween-80 and Triton X-100 all inhibited the enzyme activity by 30%. The enzyme showed affinity towards scopolin and tolerated 10% methanol and 10% ethanol solution, respectively. The enzyme specifically hydrolyzed scopolin into scopoletin from the extract of Erycibe obtusifolia Benth with a 47.8% increase of scopoletin. This demonstrated that the β-glucosidase An-bgl3 from A. niger shows specificity on scopolin with good activities, thus providing an alternative method for increasing the extraction efficiency of scopoletin from plant material.

Systematic assessment of cyflumetofen toxicity in soil-earthworm (Eisenia fetida) microcosms

Cyflumetofen was widely applied in agriculture with its excellent acaricidal effect. However, the impact of cyflumetofen on the soil non-target organism earthworm (Eisenia fetida) is unclear. This study aimed to elucidate the bioaccumulation of cyflumetofen in soil-earthworm systems and the ecotoxicity of earthworms. The highest concentration of cyflumetofen enriched by earthworms was found on the 7th day. Long-term exposure of earthworms to the cyflumetofen (10 mg/kg) could suppress protein content and increases Malondialdehyde content leading to severe peroxidation. Transcriptome sequencing analysis demonstrated that catalase and superoxide-dismutase activities were significantly activated while genes involved in related signaling pathways were significantly upregulated. In terms of detoxification metabolic pathways, high concentrations of cyflumetofen stimulated the number of Differentially-Expressed-Genes involved in the detoxification pathway of the metabolism of glutathione. Identification of three detoxification genes (LOC100376457, LOC114329378, and JGIBGZA-33J12) had synergistic detoxification. Additionally, cyflumetofen promoted disease-related signaling pathways leading to higher disease risk, affecting the transmembrane capacity and cell membrane composition, ultimately causing cytotoxicity. Superoxide-Dismutase in oxidative stress enzyme activity contributed more to detoxification. Carboxylesterase and glutathione-S-transferase activation play a major detoxification role in high-concentration treatment. Altogether, these results contribute to a better understanding of toxicity and defense mechanisms involved in long-term cyflumetofen exposure in earthworms.

Synthesis of Carvacrol-Loaded Invasomes Nanoparticles Improved Acaricide Efficacy, Cuticle Invasion and Inhibition of Acetylcholinestrase against Hard Ticks.

Carvacrol is a monoterpenoid phenol found in many essential oils that has antibacterial, antifungal and antiparasitic activities. Drug loaded-invasome systems are used to deliver drugs utilizing nanoparticles to improve bioavailability, efficacy, and drug release duration. As a result, the present study developed carvacrol-loaded invasomes and evaluated their acaricidal effect against Rhipicephalus annulatus (cattle tick) and Rhipicephalus sanguineus (dog tick). Carvacrol loaded-invasome (CLI) was prepared and characterized using UV/Vis spectrophotometer, zeta potential measurements, Scanning Transmission Electron Microscopy (STEM), Fourier Transform Infrared (FT-IR) Spectroscopy, and Differential Scanning Calorimetry Analysis. CLI (5%) induced significant mortality (100%) in R. annulatus adult ticks with LC50 of 2.60%, whereas the LC50 of pure carvacrol was 4.30%. Carvacrol and CLI were shown to have a significant larvicidal action on both tick species, with LC50s of 0.24 and 0.21% against R. annulatus and 0.27 and 0.23% against R. sanguineus, respectively. Carvacrol and CLI (5%) induced significant repellent activities for 24 h against R. annulatus and R. sanguineus, as evidenced by the rod method and the petri-dish selective area choice method, respectively. High-performance liquid chromatography (HPLC) demonstrated that the CLI form had 3.86 times the permeability of pure carvacrol. Moreover, carvacrol and CLI inhibited acetylcholinesterase activity and decreased glutathione and malonedealdehyde levels in the treated ticks. In conclusion, invasomes significantly improved adulticidal and repellency activities of carvacrol against both tick species.

Bio-efficacy of permethrin/tetramethrin and lambda-cyhalothrin treatments in habitats of hard ticks (Acari, Ixodidae) populations with confirmed Borrelia spp. infection.

The aim of the study was to evaluate the bio-efficacy of two different acaricides against mobile stages of hard ticks Ixodes ricinus, Dermacentor marginatus, and Haemaphysalis punctata in their natural habitats. The study was conducted during 2020 and 2021 at localities populated by I. ricinus as the predominant species, at which the presence of Borrelia afzelii, Borrelia garinii, and Borrelia lusitaniae was confirmed. During the first investigation year, a combination of two pyrethroids, permethrin, and tetramethrin, with an insecticide synergist piperonyl butoxide (trade name: Perme Plus®) was tested. At the first evaluation, 24h after the treatment with Perme Plus®, the efficacy expressed as a reduction rate of the population density was within the interval of satisfying performance (70-90%) at all localities, while the highest efficacy (97.8%) was recorded on the 14th post-treatment day. In the second investigation year, the formulation based on lambda-cyhalothrin (trade name: Icon® 10CS) was used. On the first post-treatment evaluation day, satisfying effects were also demonstrated. The highest recorded efficacy rate of lambda-cyhalothrin (94.7%) was recorded on the 14th post-treatment day. Both tested acaricides manifested satisfying initial acaricidal effects against mobile stages of ticks and provided long-term effects. Comparison of the regression trend lines of population reduction revealed that satisfying effects of treatment with Perme Plus® lasted until the 17th post-treatment day, while in the case of Icon® 10CS, the residual effects were significantly prolonged (30days).

The impact of Cyflumetofen on demographic parameters of two predatory mites, Neoseiulus californicus (M-G) and Phytoseiulus persimilis (A-H)

The assessment of the long-term negative effects of acaricides on the target and non-target mites can help determine the toxicity and side effects of acaricides. The sublethal concentrations can be very precise and affect populations at concentrations lower than the conventional concentration and may supplement our knowledge about its sublethal effects on the physiology and behavior of insects/mites. Furthermore, we exposed the adults' biocontrol agents mite, Phytoseiulus persimilis Athias-Henriot and Neoseuilus californicus McGregor, to the LC10 and LC30 concentrations of the Cyflumetofen and then assayed the effects of these concentrations on the growth and development of the next generations under laboratory conditions. Analyzed data showed that sublethal concentrations of cyflumetofen significantly affected both species' biological parameters, including the total lifetime, fecundity, and longevity of the treated biocontrol agents compared with the control treatment. Due to our results, when P. persimilis and N. californicus adults were exposed to LC30 concentration of cyflumetofen, the length of the oviposition period of the treated P.persimilis and N. californicus were 20.34 and 19.66 days, respectively. At the same time, these values for the control-treated P. persimilis and N. californicus were 22.51 and 22.21, respectively. The intrinsic rate of increase (r) in control were 0.203 and 0.238, while those treated with LC10 and LC30 of cyflumetofen were estimated to be 0.238 and 0.214 for P. persimilis and 0.203 and 0.223 days−1, for N. californicus, respectively. Therefore, using sublethal concentrations of cyflumetofen is emphasized for designing integrated pest management programs and makes it possible to use biocontrol agents to control the spider mite; thus, it would benefit the farmers and consumers in the long run.

Extracts of plant residues from soursop peels in the management of palm red mite

Raoiella indica Hirst, 1924 (Prostigmata: Tenuipalpidae), is one of the main pest mites of palm and banana trees, causing significant damage in producing regions. Thus, the objective of this work was to evaluate the acaricidal effect of soursop peel extract (Annona muricata L.) on R. indica adults. The experiment was conducted in a completely randomized design using soursop peel extract, with 7 replications and 12 individuals of R. indica per replication. The experimental units consisted of discs of coconut palm leaves (4 cm in diameter), with cotton moistened at the bottom of the Petri dish (10.0 x 1.2 cm) and around the disc to maintain turgor and prevent mites from escaping. The application was carried out using an airbrush, connected to a calibrated compressor with a constant pressure of 1.3 psi and 1 mL of solution per plate. The acaricidal effect was evaluated 24, 48, and 72 hours after spraying. Mortality data were corrected and subsequently submitted to probit analysis (p≤0.05) using the statistical program R, with the LC50 and LC90 of the extract being calculated. The soursop peel extract at the maximum concentration used (15%) showed mortality of 80% of individuals of R. indica. The LC50 was 1.934%. It was concluded that extracts from soursop peel have acaricidal potential on R. indica in the laboratory.

EFECTO ACARICIDA DE Pachyrhizus erosus SOBRE Varroa destructor EN COLONIAS DE Apis mellifera

<p><em><strong>Background:</strong></em><em> The main problem of beekeeping activity in Mexico is parasitosis by </em><em>Varroa destructor</em><em>, due to its wide distribution and the damage it produces in apiaries, causing mortality in bees and reduction in honey production levels. Therefore, it is essential to develop sanitary control strategies for varroasis, avoiding causing the presence of resistant vectors, harmful damage to bees, beekeepers, consumers or any type of surrounding contamination or in the main products of the hive. <strong>Objective:</strong> To evaluate the acaricidal activity of </em><em>Pachyrhizus erosus</em><em> (jicama) on the mite </em><em>V. destructor</em><em> in colonies of </em><em>Apis mellifera</em><em>. <strong>Methodology:</strong> For the obtain of the extract from mature jicama seed, the hot maceration/extraction method (bain-marie) was used, using ethanol 95° G.L (95%) as solvent. A completely random design was developed. randomized with two dilutions of </em><em>P. erosus</em><em> (5 and 10%), a negative control (distilled water) and a positive control (Cumavar®), with three repetitions, respectively. The treatments were applied by means of two plastic strips (between frames 6 and 10) impregnated with the corresponding concentrations. <strong>Results:</strong> The highest count of accumulated mites was presented in the positive control with 386 (128.67±22.74). During the sampling, an initial infestation rate of 4.54±1.64 was determined. On the other hand, the final infestation rate was 2.66±2.69. The effectiveness of the treatments was statistically significant among themselves. The 5 and 10% dilutions of the P. erosus seed extract presented an acaricidal effect with percentages greater than 45% (48.99±15.1 and 59.44±13.57% of effectiveness, respectively). Likewise, the positive control presented the highest percentage, 84.41±14.47. <strong>Implications:</strong> Trials should be developed with a greater number of experimental units and records with a longer post-application time, with the aim of evaluating their residual and harmful effect that these may have on non-target individuals such as bees. <strong>Conclusion:</strong> Exploratory data on the acaricidal effect of </em><em>P. erosus</em><em> seed on </em><em>V. destructor</em><em> and its application as a means of controlling varroa infestation were presented, as a feasible alternative for the development of strategies for the sanitary control of varroa.</em></p>

Common yarrow (Achillea millefolium) essential oil and main components as potential repellents and acaricides against Ixodes scapularis and Dermacentor variabilis (Acari: Ixodidae) ticks.

Repellent and acaricidal activities of essential oils (EO) extracted from common yarrow (Achillea millefolium L.) and main chemical components were evaluated against Ixodes scapularis and Dermacentor variabilis adult ticks and nymphs. Flowers and leaves were collected from two locations, Harvest Moon trail (HMT) and Port Williams (PW) in Nova Scotia (Canada), and EO were extracted via hydro-distillation. Samples were analyzed using GC-MS, and differences in chemical composition and quantity of compounds detected were reported in relation to the collection site and plant parts. EO were both rich in germacrene D (HMT EO 21.5 ± 1.31% wt; PW EO 25.5 ± 0.76% wt); however, HMT flower EO has a higher concentration of camphor (9.9 ± 0.08% wt) compared to PW flower EO (3.0 ± 0.01% wt). Significant acaricidal activity was reported against I. scapularis adult ticks, particularly for HMT flower EO with a LD50 of 2.4% v/v (95% confidence interval = 1.74-3.35) at 24h post-exposure. Germacrene D had the lowest LD50 of 2.0% v/v (95% CI 1.45-2.58) among the four compounds after 7 days. No significant acaricidal effect was observed on D. variabilis adult ticks. Yarrow PW flower EO exerted repellent activity towards I. scapularis nymphs (100% repellency up to 30min); however, repellency significantly declined over time. Yarrow EO exert promising acaricidal and repellent properties, that may be used to manage Ixodes ticks and the diseases they vector.

Screening of the Acaricidal Activity of Essential Oils against Panonychus citri (McGregor) (Acari: Tetranychidae)

The citrus red mite, Panonychus citri (McGregor), is an important pest of citrus in China, where pesticides are commonly used in citrus orchards. In order to reduce the use of chemical pesticides against P. citri and the development of resistance, the screening of biological control agents has attracted the attention of students. In this study, seven plant essential oils with high toxicity were selected from 40 plant essential oils by the leaf-dip bioassay, including plant essential oils of lemongrass, patchouli, juniper berry, sage, clove, frankincense, and citrus. The LC50 after 72 h treatment were 3.198 μL/mL, 8.312 μL/mL, 3.244 μL/mL, 6.701 μL/mL, 8.350 μL/mL, 21.953 μL/mL, and 8.788 μL/mL, respectively. According to the LT50, the essential oils’ acute toxicity to P. citri from high to low were lemongrass, juniper berry, patchouli, citrus, sage, vetiver, and frankincense essential oils. In general, lemongrass and juniper berry essential oils have the best acaricidal effect and have high application value for the biological control of P. citri, which provides a basis for the development of botanical acaricides.

Potential use of essential oils from Origanum vulgare and Syzygium aromaticum to control Tetranychus urticae Koch (Acari: Tetranychidae) on two host plant species.

Plant extracts and essential oils are considered alternatives to synthetic chemicals with toxic effects on insects and mites. Acaricidal, repellent, and oviposition effects of commercially available essential oils of Origanum vulgare L. (Lamiaceae) and Syzygium aromaticum (L.) (Myrtaceae) were investigated in this study on Tetranychus urticae Koch (Acari: Tetranychidae), one of the main pests in agriculture, on two host plant species using leaf disc bioassays. O. vulgare essential oil showed higher toxicity to T. urticae protonymphs and adult females inhabiting both bean and tomato leaves than S. aromaticum essential oil. The LC50 values of O. vulgare essential oil were found to be 1.67 and 2.05 µl L-1 air for the bean populations in protonymphs and adult females and 1.87 and 3.07 µl L-1 air for the tomato populations, respectively. Five percent concentration of S. aromaticum essential oil had the highest repellent effect on the bean population of T. urticae after 1, 24, and 48 h, resulting in 61.22%, 40.81%, and 18% repellence, respectively. Although O. vulgare showed higher toxic effects, S. aromaticum was a better repellent against the bean population of T. urticae. The mortality rates of adult females of T. urticae treated with either O. vulgare or S. aromaticum essential oil increased with the increasing concentration and time on both host plants. Both essential oils caused a decrease in egg number and larvae hatching in both bean and tomato populations of T. urticae. In the light of the results obtained, O. vulgare and S. aromatium essential oils have the potential to be used in the control programs against T. urticae in both host plants.

Persistent activity and therapeutic efficacy of Delcid® 7.5 against scab mites (<i>Psoroptes ovis</i>) in sheep

The purpose of the research is to study persistent activity and therapeutic efficacy of Delcid® 7.5 against scab mites Psoroptes ovis in sheep.Materials and methods. The studies were performed in the Bukhty peasant farm enterprise in November 2021 on the Kizlyarsky District winter pastures in the Republic of Dagestan. Three groups of sheep were formed, of which two groups (second and third) had a confirmed clinical diagnosis of psoroptic mange (P. ovis) and one group (first) was free from scab mites. Sheep from the first and second groups were treated with Delcid at a dose of 10 ml of the drug per animal. After 10 days, sheep from the second group were treated with the drug repeatedly at the same dose. Sheep from the first and second groups were treated with the drug applied on dry and intact skin of the back along the spine using the drop method. The third control (infected) group of animals was not treated. All experimental groups of sheep were kept in a common flock. The Delcid persistent activity and thera-peutic efficacy were evaluated by clinical examination and microscopy of the skin for P. ovis mites before the experiment started and at 1, 3, 7, 10, 14, 21, 25 and 30 days after treatment in the first group and at 1, 3, 7, 11, 13, 17, 20, 24, 31, 35 and 40 days in the second and third groups of sheep.Results and discussion. It was found that Delcid 7.5 showed persistent activity in sheep against psoroptic mange pathogens for 21 days after a single treatment at a dose of 10 ml per animal. Delcid acaricidal effect after double treatment against P. ovis was 31 days.

Side effects of abamectin and hexythiazox on seven predatory mites

Abstract Use of acaricides has become a common practice to control pests all over the world including Saudi Arabia. In spite of killing the targeted pests, such insecticides also effect growth of predatory mites. Present study has been conducted to evaluate the impact of two acaricides, abamectin and hexythiazox, on seven species of predatory mites. Standard solutions of abamectin (8.4% w/v) and hexythiazox (10% w/w) were purchased and prepared for direct spray. Acaricides were tested at three serial concentrations of recommended dose (RD), half of the recommended dose (HRD) and double the recommended dose (DRD). Trials were made on eggs, nymphs and adults of the seven species of predatory mites under laboratory conditions. Effect of the applied acaricides was determined one week after the application. The results of the study revealed that all doses of hexythiazox and abamectin are toxic to the nymphs and adults of all seven species of predatory mites but to the variable extent. Furthermore, it was observed that hexythiazox and abamectin reduced the percentage of egg hatching for all seven species of predatory mites. Hexythiazox was found to be more toxic than abamectin to all seven predatory mites. Higher mortality was recorded at DRD and RD, while minimum mortality was recorded at HRD. Acaricidal effect is less severe on hatching eggs than on immatures and adults of the predatory mites. Species vary in susceptibility to acaricides and in some populations resistance has been observed. Based upon this study, it is recommended that the frequent use of acaricides against phytophagous mites should be avoided and feasibility of biological control programs should be promoted to protect the environment, health of living individuals and the non-target organisms.