Repellent activity of urea-formaldehyde microencapsulated Ocimum basilicum L. essential oil in cotton fabric against Aedes aegypti

The Philippines reported the highest number of dengue cases in the Western Pacific Region, as indicated in the 2023 update of the World Health Organization (WHO). Mosquito repellents play a crucial role in protecting humans from infected mosquitoes. However, commercial repellents may cause adverse effects when applied directly to the skin. This study examined the repellent activity of urea-formaldehyde micro-encapsulated Ocimum basilicum L. essential oil (OBLEO) applied to cotton fabric against Aedes aegypti. OBLEO was microencapsulated at 2%, 4%, and 6% concentrations using a urea-formaldehyde polymer and applied to cotton fabric via the bath exhaustion method. Repellency was assessed using the WHO cone test in four replicates. An untreated fabric served as the negative control, while fabric treated with a commercial repellent spray served as the positive control. GC-MS analysis identified 19 volatile com-pounds in OBLEO, with β-linalool (55.40%), eucalyptol (13.75%), and α-bergamotene (7.27%) as major components. FTIR analysis confirmed successful encapsulation of OBLEO onto the fabric, while SEM imaging showed irregular microcapsules (10–47µm) with mixed smooth and wrinkled surfaces adhered to the cotton fibers. The WHO cone test showed repellency rates of 27.50±9.57%, 40.00±8.17%, and 70.00±8.17% for 2%, 4%, and 6% OBLEO-treated fabrics, respectively. ANOVA revealed a statistically significant difference among the groups (p<0.05), with 6% OBLEO being the most effective. While the commercial repellent showed higher efficacy overall, the study demonstrates that OBLEO microencapsulated in cotton fabric can provide effective mosquito repellency, especially at higher concentrations.