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Mites have been a persistent infectious disease affecting both humans and animals since ancient times. In veterinary clinics, the primary approach for treating and managing mite infestations has long been the use of chemical acaricides. However, the widespread use of these chemicals has resulted in significant problems, including drug resistance, drug residues, and environmental pollution, limiting their effectiveness. To address these challenges, researchers have shifted their focus towards natural products that have shown promise both in the laboratory and real-world settings against mite infestations. Natural products have a wide variety of chemical structures and biological activities, including acaricidal properties. This article offers a comprehensive review of the acaricidal capabilities and mechanisms of action of natural products like plant extracts, natural compounds, algae, and microbial metabolites against common animal mites.

Green and nanoacaricides including essential oil (EO) nanoemulsions are important compounds to provide new, active, safe acaricides and lead to improvement of avoiding the risk of synthetic acaricides. This study was carried out for the first time on eriophyid mites to develop nanoemulsion of garlic essential oil by ultrasonic emulsification and evaluate its acaricidal activity against the two eriophyid olive mites Aceria oleae Nalepa and Tegolophus hassani (Keifer). Acute toxicity of nanoemulsion was also studied on male rats. Garlic EO was analyzed by gas chromatography–mass spectrometry (GC-MS), and the major compounds were diallyl sulfide (8.6%), diallyl disulfide (28.36%), dimethyl tetrasulfide (15.26%), trisulfide,di-2-propenyl (10.41%), and tetrasulfide,di-2-propenyl (9.67%). Garlic oil nanoemulsion with droplet size 93.4 nm was formulated by ultrasonic emulsification for 35 min. Emulsification time and oil and surfactant ratio correlated to the emulsion droplet size and stability. The formulated nanoemulsion showed high acaricidal activity against injurious eriophyid mites with LC 50 298.225 and 309.634 μg/ml, respectively. No signs of nanoemulsion toxicity were noted in treating rats; thus, it may be considered non-toxic to mammals. Stability of garlic oil nanoemulsion, high acaricidal activity, and the absence of organic toxic solvents make the formulation that may be a possible acaricidal product. Results suggest the possibility of developing suitable natural nanoacaricide from garlic oil.

The two-spotted spider mite, Tetranychus urticae, also known as the red spider, is one of the most harmful pests in agriculture and causes large losses of many crops. These mites have rapidly developed a resistance to many chemical pesticides in recent years. In this study, the essential oil of seeds of the anise plant (Pimpinella anisum) was extracted by hydrodistillation, and the chemical composition of the oil was analyzed. The antioxidant activity of the volatile oil was determined by the DPPH radical scavenging assay. The acaricidal activity of the anise oil, a natural acaricide, was evaluated for its ability to protect green bean plants from mite injury. The two-spotted spiders were spread on green bean seedlings for 1 week; then, different plants were sprayed with different concentrations of anise oil (10, 20, 30, or 40 µL/L). Our results revealed that anethole was the major component of anise oil, at 53.23%. The acaricidal effect of the various concentrations on T. urticae was recorded after 24, 48, and 72 h of treatment. Our findings suggest that anise oil showed significant acaricidal activity against T. urticae in a dose- and time-dependent manner. Anise oil at a concentration of 40 µL/L killed 96.0% of the red spiders after 72 h. Also, all concentrations of anise oil inhibited acetylcholinesterase, and the spiders’ protease activity declined when the plants were treated with 30 or 40 µL/L of anise oil. The concentrations of 10 and 20 µL/L did not significantly affect the protease activity of T. urticae mites. We can conclude that anise oil exhibited acaricidal activity against T. urticae and that this was highly correlated with the inhibition of acetylcholinesterase and protease activities in the mites.

Carvacrol derived from Origanum vulgare oil was evaluated for its acaricidal efficacy and mechanism of action against Haemaphysalis longicornis, a primary vector of severe fever with a thrombocytopenia syndrome. Essential oils extracted from O. vulgare leaves cultivated in Germany, Albania, and Iran were analyzed. Among them, the German oil exhibited the highest acaricidal potency due to its elevated carvacrol content (83.38%). Carvacrol was isolated and its identity was confirmed using GC/MS, NMR, and FT-IR analyses. Carvacrol demonstrated significant toxicity across all developmental stages of H. longicornis, with LC50 values of 3.47, 8.21, and 15.27 μg/cm3 for larvae, nymphs, and adults, respectively—representing 4.4-, 3.5-, and 3.2-fold higher potency compared to diethyltoluamide. The acaricidal mechanism of carvacrol involved multiple pathways: (i) inhibition of acetylcholinesterase activity by up to 85.4%, leading to neural disruption; (ii) suppression of cytochrome P450 monooxygenases (47.4% reduction), α-esterase (24.8% reduction), and β-esterase (28.6% reduction); and (iii) disruption of neural signaling pathways critical for survival. Chemical analysis confirmed carvacrol as the predominant active component in O. vulgare oil, with additional contributions from thymol and thymoquinone. Although its concentration in Iranian oil was lower, thymoquinone demonstrated the highest acaricidal potency (4.98 μg/cm3). Nevertheless, the abundance and superior efficacy of carvacrol establish it as the primary component contributing to the oil’s bioactivity. This study demonstrates that carvacrol is a promising eco-friendly alternative to synthetic acaricides for the control of H. longicornis. Its ability to inhibit acetylcholinesterase activity and suppress detoxifying enzymes suggests potential for overcoming resistance mechanisms associated with synthetic chemicals. Further studies should focus on optimizing the formulations and applying them in the field to improve efficacy.

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, β-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.

Rhipicephalus microplus (Acari: Ixodidae) is a highly invasive tick responsible for significant economic losses to cattle industry worldwide. The increasing global reports on acaricide resistant tick populations warrant development of alternate eco-friendly approaches for suppressing the tick populations and vectored pathogens. The present study aimed to evaluate the acaricidal activity of essential oils (EOs): Cedar oil (CO), Garlic oil (GO), Peppermint oil (PO) and their combinations against R. microplus by larval packet test. Six concentrations each of individual EOs and their combinations (10, 5, 2.5, 1.25, 0.625 and 0.31%) were evaluated. The lethal concentrations (LC) of individual EOs and their combinations along with values of Combination Index (CI) and Dose Reduction Index (DRI) were estimated to assess the effects of interactions (synergistic, additive or antagonistic) of EO mixtures. Among the individual oils, GO showed the highest efficacy with lowest LC50, LC90 and LC95 (95% CL) values at 2.19% (1.96–2.43%), 4.00% (3.48–4.98%) and 4.74% (4.01–6.23%), respectively. Among combinations, highest acaricidal property was exhibited by GO + PO (LC50, LC90 and LC95 values of 2.63, 4.87 and 5.81%) with CI value of 0.598 indicating moderate synergism, while the CO + GO + PO combination (LC50, LC90 and LC95 values of 1.67, 9.97 and 16.54%) exhibited slight synergism with CI value at 0.872 and favourable DRI of 8.24, 1.85 and 4.76 for PO, GO and CO, respectively. The present study seems to be pioneer to assess the combination effect of these EOs against R. microplus and could help in development of an effective and eco-friendly product for tick control.

The brown dog tick, Rhipicephalus sanguineus plays a significant role in transmitting pathogens to humans and animals, necessitating control measures. Given the drawbacks of synthetic chemicals, plant-based alternatives are a promising option for tick management. The present study aimed to evaluate the acaricidal potential of thyme oil (TO) and nano-formulations {thyme oil nano-emulsion (TNE), silver nanoparticles (AgNPs), and thyme nano-emulsion containing silver nanoparticles (TNE- AgNPs)} against R. sanguineus using an adult immersion bioassay. Gas chromatography-mass spectrometry (GC-MS) was used for TO analysis. The UV- visible spectroscopy, transmission electron microscopy (TEM), and particle size were used to characterize the nano-formulations. In addition, the freshly dead ticks were examined using scanning electron microscopy (SEM). The GC-MS analysis indicated that Thymol (34.08%) was the main oil component, followed by γ-Terpinene (32.99%). The TEM images revealed a spherical-shaped nano droplet with a size of ≤ 100 nm for all nanoformulations. The droplet size and polydispersity index were (445.9 & 0.325), (10.59 & 0.216), and (768.2 & 0.325) for TNE, AgNPs, and TNE-AgNPs, respectively. The calculated LC 50 values after 7 days were 11.62, 5.47, 4.08, and 2.38% for TO, TNE, AgNPs, and TNE- AgNPs, respectively. The SEM examination revealed changes in the sensilla base, spiracular plate and anal groove region of the treated ticks. Although the biological parameters of the engorged females did not differ significantly between the treatment and control groups, there was a decrease in the hatchability percent of TO (67%), TNE (65%), and TNE-AgNPs (71%) compared to the control (80%). The used materials demonstrated acaricidal activity and might be candidates for managing the dog tick, R. sanguineus. Further detailed studies are needed to enable good judgment of the use of these materials to control R. sanguineus tick.

The acaricidal activity of 30 essential oils against the poultry red mite, Dermanyssus gallinae, female adults and behavioral responses of the mites to these essential oils were investigated. Cinnamon bark oil and clove bud oil showed 100% acaricidal activity after 24 h in the 1.3 μg/m2 treatment. In addition, four components in cinnamon bark oil and three components in clove bud oil were identified using gas chromatography-mass spectrometry. Cinnamon bark oil showed the highest LD50 value among all of the components, and eugenol showed 0.97-fold higher relative toxicity (RT) than the other components of clove bud oil. The fumigant effects of both essential oils and their seven components were observed using a vapor phase toxicity bioassay. All the substances showed repellent activity except for cinnamyl acetate, which did not show any repellent response even in the > 10 μg treatment. In the experiment using the T-tube olfactometer with the 10 μg treatment of each substance, D. gallinae female adults responded to all the substances except cinnamyl acetate. However, eugenol and eugenol acetate showed an attractant effect after 240 and 120 min of treatment, respectively. These results suggest that the two studied essential oils and their components may be used as control agents against D. gallinae.

Background Hyalomma rufipes ( H. rufipes ) ticks are widespread in Africa, Europe, and Asia. They transmit crimean-congo hemorrhagic fever virus, rickettsia , and midichloria , posing a significant risk to public health and livestock development. Developing acaricides based on plant essential oils (EOs) have risen, yet matters regarding their mechanism and feasible methods for tick tests remain unanswered. The aim of this study was to identify the chemical constituents of three EOs and evaluate their acaricidal activity against larval and adult ticks of H. rufipes , as well as to establish an artificial membrane feeding technique to explore the feasibility of Cinnamomum mollifolium EO for tick control in vitro. Results In this study, gas chromatography-mass spectrometry (GC-MS) was used to analyze the constituents of C. mollifolium , Eucalyptus globulus , and Pimenta dioica EOs, as well as to investigate their potential application in H. rufipes control. The main compound in C. mollifolium EO is (E)-Cinnamaldehyde (93.15%). Eucalyptus globulus EO comprises eucalyptol (61.02%) and l-(+)-Ascorbic acid 2,6-dihexadecanoate (35.89%). Pimenta dioica EO predominantly includes eugenol (73.67%), 1,2-dimethoxy-4-(2-propenyl)-benzene (13.04%), and caryophyllene (7.24%). Larval packet tests revealed that the EOs of C. mollifolium , E. globulus , and P. dioica exhibited notable larvicidal activity, with lethal concentration (LC 50 ) values of 8.84, 51.16, and 34.58 mg/ml, respectively. Adult immersion tests indicated that the EOs of C. mollifolium , E. globulus , and P. dioica had significant acaricidal activity against adult ticks, with LC 50 values of 15.51, 43.96, and 29.83 mg/ml, respectively. Artificial membrane feeding technology enabled successfully in vitro rearing of adult male and female ticks with attachment rates of 83.4% and 75.0% respectively. The most effective EO ( C. mollifolium ) was applied on ticks after attachment to an artificial membrane, and showed acaricidal activity with high adult mortality at higher concentrations. Conclusion This study offers useful information on the chemical makeup and tick-killing ability of essential oils from C. mollifolium , E. globulus , and P. dioica against ticks. The acaricidal potency of C. mollifolium EO significantly surpasses that of both E. globulus and P. dioica EOs. The effective use of artificial membrane feeding technology also highlights its value for future tick control research and applications. Graphical Abstract

Background Haemaphysalis doenitzi is a parasite mainly found on the body surface of birds that is capable of transmitting rickettsiae and borrelia, which can cause serious zoonotic diseases. Chemical acaricides are controversial because they pollute the environment and predispose ticks to resistance. In contrast, plant essential oils (EOs) are favored for their effective acaricide properties and environmental friendliness. Methods The constituents of Origanum onites and Ocimum gratissimum EOs were profiled using gas chromatography-mass spectrometry (GC-MS). Acaricidal activities were evaluated by immersing unfed nymphs and adults of H. doenitzi in serial solutions for 5 min and monitoring mortality after 24 h. Enzyme activities (Na⁺/K⁺-ATPase, GST, CarE, AChE) and transcript levels of HDABCE1, HDCYP450a and HD-GSTa were quantified in homogenates of treated survivors. Homology models of the three target proteins were generated and docked with carvacrol and eugenol to predict binding sites and affinities. Results GC–MS analysis showed 93.3% of carvacrol in O. onites EO and 66.68% of eugenol in O. gratissimum EO. Immersion test showed that O. onites EO had significant acaricidal activity against nymphs and adults, with median lethal concentration (LC 50 ) values of 14.694 mg/ml and 24.357 mg/ml, respectively. Ocimum gratissimum EO showed significant acaricidal activity against nymphs and adults, with LC 50 values of 9.379 mg/ml and 18.299 mg/ml, respectively. Carvacrol also showed significant acaricidal activity against unfed nymphs and adults. Repellency tests showed that O. onites EO had more significant repellent activity against nymphs than DEET, with median effective concentration (EC 50 ) values of 2.162 mg/ml and 7.039 mg/ml, respectively. To explore the molecular mechanisms of O. onites EO and carvacrol on ticks, we investigated the enzyme activity and gene expression of ATP-binding cassette transporter, cytochrome P450, and glutathione S-transferase. Finally, molecular docking was used to verify the enzyme effects. Conclusions The results of this study provide important insight into the toxicity mechanisms of ticks, and indicate that carvacrol and O. onites EO can be used as alternatives to chemically synthesized acaricides. Graphical Abstract