An investigation of the acaricidal activity of benzyl alcohol on Rhipicephalus annulatus and Rhipicephalus sanguineus and its synergistic or antagonistic interaction with commonly used acaricides

Tick-borne pathogens from ruminant ticks in a Mediterranean ecosystem from Eastern Spain

Vector-borne diseases represent various sicknesses that are increasingly significant in human and veterinary health. Among the zoonotic agents transmitted by ticks, infections caused by the intracellular pathogens from the Anaplasmataceae family and piroplasmids (Babesia/Theileria spp.) are particularly notable due to the substantial economic losses they cause in the livestock sector. A study was carried out to assess the prevalence of these pathogens in ticks from ruminants in the province of Valencia (Eastern Iberian Peninsula). Between 2019 and 2022, 1674 ticks were collected from 163 domestic and wild ruminants. The tick species were identified using molecular and morphological features and included Rhipicephalus spp. (Rhipicephalus bursa and Rhipicephalus sanguineus) (88.7%), Haemaphysalis sulcata (5.9%), Ixodes ricinus (3.6%) and Dermacentor marginatum (1.2%). The Spanish ibex (Capra pyrenaica) was found to be at greater risk of infestation by Haemaphysalis compared to other ruminants. Polimerase Chain Reaction (PCR) analysis was performed on 108 individual ticks from different hosts, with 16.7% testing positive for members of the Anaplasmataceae family and 39.8% for Theileria spp. Sequencing of 10 positive samples from each pathogen group revealed the presence of Anaplasma ovis, Anaplasma platys, Ehrlichia spp., Theileria ovis and Theileria capreoli. No Anaplasma phagocytophilum or Babesia spp. were detected. Further research is essential for improved management of ticks and the diseases they transmit in the study area.

Benzyl alcohol synergistic effect with deltamethrin against Musca domestica with molecular docking of potential modes of action

The house fly (Musca domestica Linnaeus, 1758) has developed resistance to several pesticides, necessitating innovative approaches for effective control. This study explores the synergistic effects of benzyl alcohol (BA) on the toxicity of deltamethrin (D) against various life stages of M. domestica larvae, pupae and adults. Additionally, molecular docking analyses were conducted to investigate interactions with the acetylcholinesterase enzyme (AChE) and voltage-sensitive sodium channel (Vssc). Two formulations of deltamethrin were tested: deltamethrin + benzyl alcohol (DBA) mix (D 5% dissolved in ethyl alcohol, then mixed with BA at its LC50 concentration) and DBA combination (D 5% dissolved directly in pure BA). In vitro testing revealed significant synergistic effects. For larvae, the LC50 of deltamethrin alone was 0.95 mg/mL, while the DBA mix reduced it to 0.09 mg/mL, yielding a synergism factor of 10.56. For pupae, deltamethrin's LC50 was 1.32 mg/mL, compared with 0.104 mg/mL for the DBA mix, with a synergism factor of 12.69. The DBA combination also exhibited notable toxicity, with LC50 values of 0.14 mg/mL for larvae and 0.16 mg/mL for pupae, corresponding to synergism factors of 6.79 and 8.80, respectively. Against adult flies, the DBA mix and DBA combination demonstrated high fumigant toxicity, with LC50 values of 0.08 mg/L and 0.09 mg/L air, respectively, and synergism factors of 9.31 and 8.11. Docking analyses showed that deltamethrin exhibited a strong binding affinity to AChE, forming two hydrogen bonds with Lys480 and a pi-sigma interaction with Met351. BA occupied a separate binding pocket in AChE, forming two hydrogen bonds with Met309 and Lys335. Both compounds demonstrated strong, distinct binding affinities, confirming their synergistic inhibition of AChE. Against Vssc, deltamethrin (ΔG = -5.90 kcal/mol) formed a pi-pi interaction with Phe78 and a hydrogen bond with Lys79, while BA (ΔG = -3.79 kcal/mol) interacted with a different pocket via hydrophobic interactions. These findings highlight the potential of combining BA with deltamethrin to overcome insecticide resistance in house fly populations, offering a promising strategy to enhance pest control effectiveness.

Toxicity of Common Acaricides, Disinfectants, and Natural Compounds against Eggs of Rhipicephalus annulatus

Ticks pose a significant threat due to their ability to lay thousands of eggs, which can persist in the environment for extended periods. While the impact of various compounds on adult and larval ticks has been studied, research on their efficacy against tick eggs is limited. This study evaluated the ovicidal activity of commercial acaricides, disinfectants, and natural products against Rhipicephalus annulatus eggs using the egg hatch assay (EHA). Deltamethrin and cypermethrin caused a non-significant inhibition of hatching (IH%), even at concentrations higher than the recommended levels. By contrast, the acaricides chlorpyrifos, phoxim, and amitraz significantly inhibited hatching at all tested concentrations. Ivermectin also demonstrated significant IH% at various concentrations but did not fully inhibit the hatching process. Among the disinfectants tested, Virkon-S®, TH4, and Chlorox showed insignificant effects, whereas formalin achieved an IH% of only 34.1% at a high concentration of 200 mg/mL. Natural products, carvacrol and thymol, exhibited significant ovicidal activity, with a significant IH%. In a semi-field application, phoxim (0.5 mg/mL) and deltamethrin (0.05 mg/mL) were sprayed on tick eggs on pasture soil from a farm. The results indicated that phoxim-treated eggs had a 40% IH%, while deltamethrin-treated eggs showed only an 8.79% IH%. In conclusion, the acaricides amitraz, phoxim, and chlorpyrifos, as well as the natural products carvacrol and thymol, caused significant toxicity to R. annulatus eggs.

A novel 2D Eu-MOF as a dual-functional fluorescence sensor for detection of benzaldehyde and Fe3

Lanthanide metal-organic frameworks (Ln-MOFs) have unique advantages in sensing due to their excellent optical properties. In this study, we synthesized a dicarboxylic acid ligand with amide groups and successfully synthesized a novel two-dimensional (2D) MOF with the molecular formula C42H31EuN4O10 (Eu-MOF) by a solvothermal method. Single-crystal X-ray diffraction showed that amide groups are exposed on the outside of the two-dimensional coordination layer, with the possibility of recognizing specific molecules through hydrogen bonding interactions. The ligand's "antenna effect" enables Eu-MOF to emit a strong luminescence characterized by the "f-f" transition. Further studies have revealed that Eu-MOF could be used as a bifunctional fluorescent probe for the selective detection of benzaldehyde and Fe3+. The sensing mechanism has been analyzed in detail through powder X-ray diffraction (PXRD) analysis, UV-vis spectroscopy, fluorescence lifetime measurement, and density functional (DFT) theory calculation. This design and research can provide a reference for subsequent related work.

Toxicity and Repellency Efficacy of Benzyl Alcohol and Benzyl Benzoate as Eco-Friendly Choices to Control the Red Flour Beetle Tribolium castaneum (Herbst. 1797)

Tribolium castaneum is a damaging pest of stored grains, causing significant losses and secreting lethal quinones, which render the grains unfit for human consumption. Chemical insecticides are the most commonly used approach for control; however, they create insecticide resistance and affect the health of humans, animals, and the environment. As a result, it is critical to find an environmentally friendly pest-management strategy. In this study, two naturally occurring chemicals, benzyl alcohol (BA) and benzoyl benzoate (BB), were investigated for insecticidal activity against T. castaneum using different assays (impregnated-paper, contact toxicity, fumigant, and repellency assays). The results showed that BA had a significant insecticidal effect, with the LC50 achieved at a lower concentration in the direct-contact toxicity test (1.77%) than in the impregnated-paper assay (2.63%). BB showed significant effects in the direct-contact toxicity test, with an LC50 of 3.114%, and a lower toxicity in the impregnated-paper assay, with an LC50 of 11.75%. Furthermore, BA exhibited significant fumigant toxicity against T. castaneum, with an LC50 of 6.72 µL/L, whereas BB exhibited modest fumigant toxicity, with an LC50 of 464 µL/L. Additionally, at different concentrations (0.18, 0.09, 0.045, and 0.0225 µL/cm2), BA and BB both showed a notable and potent repelling effect. BA and BB significantly inhibited acetylcholinesterase, reduced glutathione (GSH), and increased malondialdehyde (MDA) in treated T. castaneum. This is the first report of BA insecticidal activity against the red flour beetle. Also, the outcomes of various assays demonstrated that the application of BA induces a potent bio-insecticidal effect. BA may be a promising eco-friendly alternative to control T. castaneum due to its safety and authorization by the EFSA (European Food Safety Authority).