Acaricidal properties of 5-methylfurfural identified from Valeriana fauriei and its structural analogues against synanthropic mites and Asian longhorned tick with color alterations

Acaricidal activities and color alterations of 5-methylfurfural derived from Valeriana fauriei essential oil and its structural analogues against Dermatophagoides farinae, D. pteronyssinus, Haemaphysalis longicornis and Tyrophagus putrescentiae were evaluated in the present study. Based on the LD50 values of 5-methylfurfural and its analogues, 4,5-dimethylfurfural showed the highest acaricidal activity (LD50; 9.95, 9.91, and 7.12 μg/cm2), followed by 5-methylfurfural (11.87, 11.00, and 8.59 μg/cm2), furfural (12.94, 13.25, and 10.36 μg/cm2), and V. fauriei essential oil (15.15, 13.64, and 10.14 μg/cm2) against D. farinae, D. pteronyssinus and T. putrescentiae, respectively. However, all tested compounds did not show the acaricidal activities against H. longicornis. Interestingly, the color alterations of the mites and ticks were observed by furfural, 5-methylfurfural, and 4,5-dimethylfurfural from colorless to red brown during the acaricidal experiments. Furthermore, 4,5-dimethylfurfural which exhibited the highest acaricidal activity was formulated as nanoemulsion. The nanoemulsion of 4,5-dimethylfurfural showed higher acaricidal activity than it was emulsified in ethanol. The nanoemulsion was also found to show color changes of the mites and ticks from colorless to red brown. The results suggest that 5-methylfurfural and its analogues could be developed as an effective and easy-to-recognize acaricides to mites and ticks.

New insight on some selected nanoparticles as an effective adsorbent toward diminishing the health risk of deltamethrin contaminated water

Deltamethrin is a widely used insecticide that kills a wide variety of insects and ticks. Deltamethrin resistance develops as a result of intensive, repeated use, as well as increased environmental contamination and a negative impact on public health. Its negative impact on aquatic ecology and human health necessitated the development of a new technique for environmental remediation and wastewater treatment, such as the use of nanotechnology. The co-precipitation method was used to create Zn-Fe/LDH, Zn-AL-GA/LDH, and Fe-oxide nanoparticles (NPs), which were then characterized using XRD, FT-IR, FE-SEM, and HR-TEM. The kinetic study of adsorption test revealed that these NPs were effective at removing deltamethrin from wastewater. The larval packet test, which involved applying freshly adsorbed deltamethrin nanocomposites (48 hours after adsorption), and the comet assay test were used to confirm that deltamethrin had lost its acaricidal efficacy. The kinetics of the deltamethrin adsorption process was investigated using several kinetic models at pH 7, initial concentration of deltamethrin 40 ppm and temperature 25°C. Within the first 60 min, the results indicated efficient adsorption performance in deltamethrin removal, the maximum adsorption capacity was 27.56 mg/L, 17.60 mg/L, and 3.06 mg/L with the Zn-Al LDH/GA, Zn-Fe LDH, and Fe Oxide, respectively. On tick larvae, the results of the freshly adsorbed DNC bioassay revealed larval mortality. This suggests that deltamethrin’s acaricidal activity is still active. However, applying DNCs to tick larvae 48 hours after adsorption had no lethal effect, indicating that deltamethrin had lost its acaricidal activity. The latter result corroborated the results of the adsorption test’s kinetic study. Furthermore, the comet assay revealed that commercial deltamethrin caused 28.51% DNA damage in tick cells, which was significantly higher than any DNC. In conclusion, the NPs used play an important role in deltamethrin decontamination in water, resulting in reduced public health risk. As a result, these NPs could be used as a method of environmental remediation.

Chemical composition and insecticidal activity of Garcinia gardneriana (Planchon & Triana) Zappi (Clusiaceae) essential oil

The present study aimed to analyze the chemical composition of the essential oil from Garcinia gardneriana (Planchon & Triana) Zappi leaves and fruits, and to determine its acaricidal activity on Rhipicephalus microplus by larval packet test and larvicidal action on Aedes aegypti by larval immersion test. The chemical analysis of the essential oil by gas chromatography-mass spectrometry identified sesquiterpene hydrocarbons and oxygenated sesquiterpenes in bacupari leaves and fruits, and α-cedrene, α-chamigrene, α-trans-bergamotene, and β-curcumene as major compounds. Essential oil from leaves of G. gardneriana presented acaricidal activity on R. microplus (LC50 = 4.8 mg/mL; LC99 = 10.8 mg/mL) and larvicidal effect on A. aegypti (LC50 = 5.4 mg/mL; LC99 = 11.6 mg/mL), whereas essential oil from the fruits of G. gardneriana showed LC50 = 4.6 mg/mL and LC99 = 8.9 mg/mL against R. microplus and LC50 = 6.4 mg/mL and LC99 = 13.9 mg/mL against A. aegypti. These results thus demonstrate the potential acaricidal and larvicidal activity of essential oil of G. gardneriana, offering new perspectives for the realization of bioassays from this essential oil.